Published by Andrzej ŁEBKOWSKI, Gdynia Maritime University, Department of Ship Automation
Abstract. The paper presents the construction and properties of an electric vehicle fire extinguishing system. Parameters of several electric vehicles are presented, focusing on used traction battery types and system voltages. Various dangers that are possibly present during operation of an electric vehicle are discussed. The advantages of using the fire extinguishing system for electric vehicles are given.
Streszczenie. W pracy przedstawiono konstrukcję oraz właściwości systemu gaśniczego dla pojazdu z napędem elektrycznym. Zaprezentowano parametry wybranych samochodów elektrycznych pod kątem zastosowanych typów akumulatorów trakcyjnych oraz poziomów napięć. Omówiono zagrożenia, jakie mogą wynikać z tytułu eksploatacji pojazdów elektrycznych. Przedstawiono korzyści wynikające z zastosowania systemu gaśniczego dla pojazdów elektrycznych. (System gaśniczy dla pojazdu z napędem elektrycznym).
Słowa kluczowe: pojazdy elektryczne, system przeciwpożarowy, zwarcia elektryczne, akumulatory litowe. Keywords: electric vehicles, fire extinguishing system, short circuit, lithium batteries.
Introduction
The progress of electric propulsion systems affects the demand of electric vehicles and hybrid vehicles. Regardless the configuration of the vehicle – battery energy storage (EV, BEV, PEV, EVC), battery combined with an ICE (HEV, PHEV), fuel cell powered (FCEV), if one of the vehicles prime movers is an electric motor, then such a vehicle can be regarded as an electric vehicle. Basing on sales statistics of electric vehicles, there are predictions that in the 2040 the market share of EVs could be on the order of 35% [1,2]. In addition to vehicles marketed by automotive companies, there are numerous designs made by research institutes, academies and independent makers. The amount of vehicles converted from conventional propulsion to electric propulsion (EVC) is very high, which can be inferred from number of sale points and general demand for components needed to construct an electric vehicle. These designs, sometimes only single vehicle projects, can pose somewhat greater risk of harboring design flaws which could lead to e.g. a fire hazard. The lack of sufficient experience in design could lead to design flaws which can translate into potential hazards, including fire hazard. At the same time, with growing sales of electric vehicles, independently of applied state of the art driver aid systems, there are unavoidable, statistically determined road accidents in which these vehicles take part. Additionally, as in the case of other machines, e.g. home appliances and conventional cars, as the time passes some elements or systems of a vehicle will unavoidably reach their end of life, resulting in a malfunction.
Fig.1. Fire of the TESLA Model S during fast charging at a Supercharging station, Norway 01.2016 [2]
For the user, in the best case scenario it will mean only, that their vehicle will not work. In the worst case, the failure of one of electric propulsion system’s elements could start a fire ending in a total loss of the vehicle.
The examples of fires in electric vehicles can be found all over the world, in every place and in every type of the vehicle.
Fig.2. An example of improper placement of electric propulsion system elements [11]
The causes of fire – an uncontrolled and spontaneous combustion of matter – can be various, starting from changes in the internal structure of a material (spontaneous battery ignition), powertrain design errors (wrong choice of cable gauge, lack or insufficient protection from overcurrent and short-circuits in the cabling, inadequate protection from cable insulation abrasion damage due to vibrations present during operation, the action of others (arson), force of the nature acts (e.g. moisture short-circuiting the battery pack during flood, physical damage due to hurricane winds), and finally, road accidents (short-circuits, physical damage to cells causing their ignition).
No matter what are the reasons of physical damage of electric propulsion system components, mainly the battery pack, precautions should be taken to mitigate any dangers to life and limb as well as equipment. Moreover, any fire on board of an electric vehicle usually ends up in total loss and substantial negative financial impact on the vehicle owner’s budget. It is considered, that purely electric vehicles are safer than conventional vehicles [3] or hybrid vehicles (combining electric and conventional propulsion). The latter pose even a greater threat to human life and health due to the fact that they have the disadvantages of both propulsion types: possibility of passenger electrocution and possibility of fuel tank fire or explosion.
Dangers present in electric vehicles are associated mostly with the risk of electrocution caused by damage to the electric propulsion system sustained in a crash, as well as the risk of fire, but it’s development is not as rapid as in conventional cars. Even in case of the battery short-circuit, the fire does not appear and spread as quickly as in conventional vehicles (fig. 3), which allows the occupants more time to leave the vehicle.
Fig.3. Causes of crash between electric vehicle and conventional vehicle [4]
The practical experience in the operation of electric vehicles shows that currently used battery types are not 100% safe regarding the possibility of uncontrolled fire. There are numerous examples, where lithium batteries in cell phones, laptop computers, electric vehicles and even passenger jets have spontaneously caught fire. Virtually all types of nickel based batteries (Ni-Cd, Ni-MH) and lithium based batteries (Li-Ion, Li-Polymer) with the exception of lithium iron phosphate batteries (LiFePO4) [11,12,13,14,15,16,17] have a tendency for self-ignition when their terminals become short-circuited (by a physical short-circuit of connected wires, flooding by a conductive liquid like sea water) or by a physical damage to their internal structure (internal short-circuit caused by a damage to the separator between cell electrodes). After a short-circuit on a lithium cell, its temperature rises, the enclosure looses its seal and lets out a mixture of toxic and flammable gases line carbon monoxide or organic electrolyte vapors which results in a fire.
Fig.4. Structure of the battery box of a Nissan Leaf vehicle [7]
The threat to life and health caused by fire can be minimized by following proper guidelines and procedures in case of an accident, set forth in the handouts provided by the manufacturer of the vehicle. The presented information regards mainly the paths of the high voltage traction cables marked with orange colored conduits, as well as places where such cables can be cut after the accident takes place. The voltage on the terminals of traction battery ranges from 48 up to 650 VDC, while the voltage considered safe to humans is 120V for DC, and 60V for AC. It should also be remembered, that the cutoff of cabling powering the inverter from the battery pack does not guarantee complete safety from electrocution. Capacitive elements present in the system can hold a high voltage on the ends of separated cables for several minutes.
The solution which increases the overall safety level is to place the batteries in reinforced, metal, hermetic battery boxes, as shown in figure 4.
A less favorable approach can be displayed in the battery pack made by E4V, housed in a non-hermetic aluminum box, which also contains numerous cable harnesses and electronic components which can be a source of ignition and fire.
Fig.5. Structure of the battery box made by the E4V
The events of 2012 related to the landfall of Sandy hurricane, which caused a flood at the East Coast of the USA, contributed to flooding of 16 Fisker Karma electric vehicles, causing all of them to ignite and burn down completely [6]. A similar fate happened in 2013-2016 to Tesla made cars, which battery packs were physically damaged during operation on roads.
The presently used extinguishing means – fire extinguishers carried in each vehicle in an easily accessible place, cannot provide the vehicle’s operator full control over the spreading fire. Simultaneously, the vehicle’s construction and enclosing all the powertrain components under the hood and inside the body of the vehicle cause that any eventual fire is noticed only after it is in a very developed stage. Therefore it is recommended to install devices which indicate presence of flames or too high a temperature in the vicinity of powertrain and energy storage devices. One of the elements which can be used to fight a fire are fire systems dedicated to electric vehicles. These systems can employ various methods of firefighting including infrasound (30÷60Hz) [5]. An alternative solution is to incorporate in the internal structure of the cells a new generation of TRPS – thermo-responsive polymer switching materials [8], which disconnect a battery from its terminals during a rise in battery’s temperature and reconnect the terminals when the temperature drops. The purpose of TRPS elements is to isolate the car’s wiring from the battery. This solution however does not prevent the fire caused by a physical damage to the cells themselves.
The author is proposing an application for an electric vehicle, which employs an extinguishing agent (CO2, dry powder, etc.) which can be fed directly into the enclosure of the electrical device. This solution is an effective way to suppress any fire before it spreads, therefore saving the whole vehicle from destruction.
System structure
Fire extinguishing system for an electric vehicle consists of: a control unit, sets of sensors placed in the critical points of an electric powertrain and actuators – electromagnetic valves which when energized, release the extinguishing agent into the enclosure or next to the elements which are suspected of being in risk of fire.
Fig.6. Structure of the fire extinguishing system for an electric vehicle
Fig.6. Structure of the fire extinguishing system for an electric vehicle, where:
1-traction motor/motors, 2-power inverter, 3-electrical energy store (battery), 4-AC/DC converter (battery charger), 5-fire and temperature sensors installed on the motor, 6-fire and temperature sensors installed on the power inverter, 7-fire and temperature sensors installed on the battery charger, 9-GSM communication module, 10-ambient temperature sensor, 11-front impact sensor, 12-rear impact sensor, 13-extinguishing agent tank, 14- electromagnetic valve spraying the motor, 15-electromagnetic valve spraying the inverter, 16-electromagnetic valve spraying the battery, 17-electromagnetic valve spraying the battery charger, 18- user interface with alarming function, for communicating the user the actions taken by the fire system, 19-extinguishing agent tank pressure sensor, 20-main contactor connecting the battery to the high voltage vehicle cabling, 21-internal contactor in the battery pack.
In case the batteries in the vehicle are divided into separate battery packs, every pack should be fitted with a set of sensors, electromagnetic valve supplying the extinguishing agents into the box, and contactor which disconnect the high voltage wiring from the batteries. The Control Unit of the fire system can be implemented using a microcontroller (e.g. an ATMEL Atmega324PA). The schematic diagram of the fire system for an electric vehicle structure is presented in the figure 6.
System functions
The main element governing the operation of the fire extinguishing system for an electric vehicle is the Control Unit (CU), into which various sensor signals are supplied, such as: fire and temperature sensors installed on the motor, fire and temperature sensors installed on the power inverter, fire and temperature sensors installed on the battery charger, ambient temperature sensor, rear and front impact sensors. The schematic diagram of the fire extinguishing system for an electric vehicle is presented in the figure 7. In the event, the control algorithm programmed into the control unit memory detects, that the signal value on any sensor measuring the temperature on the battery pack (TB – Battery Temperature), the motor (TM – Motor Temperature), the inverter (TI – Inverter Temperature) or the battery charger (TCh – Charger Temperature) exceeds the threshold of reference signal, or any of the fire sensors (FSB – Battery Fire Sensor, FSM – motor fire sensor, FSI – Inverter Fire Sensor, FSCh – Charger Fire Sensor) or impact sensors (11,12) have been activated, the control unit (CU) first disconnects the high voltage circuit by opening the main contactor (20) (with simultaneous opening of the internal contactor (21)) and opens the corresponding electromagnetic valve of the device which sensor has been activated, therefore spraying the inside of given device with the extinguishing agent. Activation of only the impact sensor(s) will just open the contactors.
Fig.7. Fire system schematic diagram
The reference value threshold, for opening the electromagnetic valves can be independently set for each of the protected powertrain elements: battery temperature TB>90°C, motor temperature TM>150°C, inverter temperature TI>100°C, charger temperature TCh>100°C. The temperature threshold values were selected basing on thermal characteristics of lithium cells [18,19,20]. Each type of chemical battery, including lithium based cells, is subjected to self-heating which can be in simplification treated as proportional to the product of squared current flowing through the cell and the cell’s internal resistance. There is a point, however, where the cell’s temperature will begin to rise on its own, either after reaching a certain temperature due to short-circuit or after a mechanical damage to the electrode separator membrane causing and internal short. For lithium-ion and lithium-polymer cells, at ca. 150°C their safety valve bursts, releasing noxious fumes to the surrounding atmosphere. These gasses can include carbon monoxide (CO), hydrogen fluoride (HF) and phosphorous oxyfluoride (POF3). After exceeding ca. 200°C a thermal runaway process starts, resulting in fast increase of cell’s temperature to about 690°C with presence of flames. Once the runaway starts, the cell’s temperature rises on its own, as the reaction is exothermic. The lithium iron phosphate (LFP) cells reacted slightly different, while they too started to vent gasses at about 150°C, the flames were not present [18].
The fire system, through the user interface, can inform the driver of the actual thermal parameters of the monitored devices, and allows the definition of pre-alarm threshold values. This function allows to alert the user in case the temperature of monitored devices is dangerously high by displaying an appropriate message on the HMI LCD display. Additionally, in case the pressure of the extinguishing agent in the tank drops below the preset value, the fire system can inform the user of this fact. In case the fire breaks out (as indicated by the fire sensor), or the temperature thresholds for powertrain elements are exceeded, the control unit will: turn off the high voltage circuit by opening the contactor (20), isolate the battery by opening the contactor (21), open the appropriate valve releasing the extinguishing agent onto the device in which the fire or elevated temperature was detected. In case only the impact sensors have been activated, the only direct action of the fire system will be deactivating the contactors and displaying a message on the display. In case the impact results in further fire, the system will then react accordingly. The HMI LCD will display a message about the alarm and the measures taken by the fire system. As an extra function, the fire system can remotely warn the user of the fire hazard via an SMS. A short message is sent to the user-defined telephone number, with the information about the event (fire, high temperature or impact) and actions taken by the control unit.
Fig.8. Control algorithm programmed into the control unit’s memory
Summary
The presented fire extinguishing system for an electric vehicle, basing on data from temperature sensors, flame sensors and impact sensors, can alert the vehicle’s driver about a fire in the vehicle and proceed with immediate preventive action. The fire system has an advantage over the other solutions, which are limited to disconnecting the battery, that it can react further, by actively trying to extinguish the present fire.
The fire extinguishing system for an electric vehicle can interact with other diagnostic and monitoring systems including remote notification of emergency services, and remote electric vehicles diagnostics.
The installation of the fire system can minimize the financial loss which could arise from a fire, as well as increasing the safety level for the vehicle occupants and other traffic participants. Application of the fire system for an electric vehicle together with other technologies, like thermal management system, battery management system, battery short-circuit protection, proactive cell design and packing (mechanical crash protection, flood protection), can synergistically increase the level of safety and allows longer life of the battery.
REFERENCES
[1] Randall T., Here’s How Electric Cars Will Cause the Next Oil Crisis, Bloomberg, http://www.bloomberg.com, 02.2016. [2] Herron D., Model S Catches Fire in Norway at Supercharger, charging system seemingly at fault, The Long Tail Pipe, http://www.longtailpipe.com, 01.2016. [3] Herron D., Electric Cars Are Safer Than Gasoline Cars, The Long Tail Pipe, http://www.longtailpipe.com, 08.2015. [4] Loveday E., Crash Involving Tesla Model S And Gas-Fueled Car Results In ICE Vehicle Fire, INSIDE EVs, http://www.insideevs.com, 04.2016. [5] Prindle D., Fighting Fire With Bass? Sounds Crazy, But These College Students Are Making It Happen, DIGITAL TRENDS, http://www.digitaltrends.com, 03.2015. [6] Herron D., Fisker Determines Cause of Karma Fires Following Hurricane Sandy Flooding, The Long Tail Pipe, http://www.longtailpipe.com, 11.2012. [7] DeMorro Ch., 99.99% Of Nissan LEAF Batteries Still In Operation, Clean Technica, http://www.cleantechnica.com, 03.2015. [8] Chen Z., Hsu P.H., Lopez J., Li Y., To J.W.F., Liu N., Wang Ch., Andrews S.C., Liu J., Cui Y., Bao Z., Fast And Reversible Thermoresponsive Polymer Switching Materials For Safer Batteries, Nature Energy, article no. 15009, DOI: 10.1038/NENERGY.2015.9, 01.2016. [9] Kelly T., Scott A., Japan Air Grounds Boeing 787 After Battery Problem, REUTERS, http://www.reuters.com, 01.2014. [10] Chanson C., Safety of lithium-ion batteries, The European Association for Advanced Rechargeable Batteries, 2013. [11] The Electric Vehicle Photo Album, http://www.evalbum.com, 2016. [12] Hu G., Duan S., Cai T., Liu B.C., Modeling, Control and Implementation of a Lithium-ion Battery Charger in Electric Vehicle Application, Przegląd Elektrotechniczny, 01b (2012), p.255-258. [13] Pereirinha P., Trovao J., Santiago A., Set up and test of a LiFePO4 battery bank for electric vehicle, Przegląd Elektrotechniczny, 01a (2012), p.193-197. [14] Liu H. , Chen X., Wang X., Overview and Prospects on Distributed Drive Electric Vehicles and Its Energy Saving Strategy, Przegląd Elektrotechniczny, 07a (2012), p.122-125. [15] Fan L., Liu Y., Fuzzy Logic Based Constant Power Control of a Proton Exchange Membrane Fuel Cell, Przegląd Elektrotechniczny, 05b (2012), p.72-75. [16] Souza D.A., Pinto V.P., Nascimento L.B.P., Torres J.L.O., Gomes J.P.P., Sá Junior J.J.M., Almeida R.N.C., Battery Discharge forecast applied in Unmanned Aerial Vehicle, Przegląd Elektrotechniczny, 02 (2016), p.185-192. [17] Jaroszyński L., Secondary lithium batteries for electric vehicles, Przegląd Elektrotechniczny, 08 (2011), p.280-284. [18] Larsson F., Andersson P., Mellander B.E., Lithium-Ion Battery Aspects on Fires in Electrified Vehicles on the Basis of Experimental Abuse Tests, Batteries 2016, 2, 9; doi:10.3390/batteries2020009, (2016). [19] Volck T., Sinz W., Gstrein G., Breitfuss Ch., Heindl S.F., Steffan H., Freunberger S., Wilkening M., Uitz M., Fink C., Geier A., Method for Determination of the Internal Short Resistance and Heat Evolution at Different Mechanical Loads of a Lithium Ion Battery Cell Based on Dummy Pouch Cells, Batteries 2016, 2, 8; doi:10.3390/batteries2020008, (2016). [20] Zhang Ch., Li K., Deng J., Real-time estimation of battery internal temperature based on a simplified thermoelectric model, Journal of Power Sources, 302 (2016) p.146-154.
Author: dr inż. Andrzej Łebkowski, Akademia Morska w Gdyni, Katedra Automatyki Okrętowej, ul.Morska 83, 81-225 Gdynia, E-mail: andrzejl@am.gdynia.pl.
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 93 NR 1/2017. doi:10.15199/48.2017.01.77
Published by Wiktoria GRYCAN, Wroclaw University of Science and Technology ORCID: 0000-0001-8121-7612
Abstract. Battery electric vehicles are becoming an opportunity for sustainable development in mining. There are several advantages of electric vehicles in mining, primarily related to improving the safety of miners’ working conditions. It is significant for mining workers that electric vehicles are not a significant additional source of heat, reduce the emission of exhaust gases in the environment of their use, and are characterized by very little or no harmful gases released into the atmosphere. Currently, the mining industry is developing several initiatives for sustainable development, bringing together mining companies, suppliers and research institutions to accelerate technology development and effectively implement BEVs (battery electric vehicles) in the mining industry as soon as possible. These activities are accepted by miners, although, like any modern technology, they raise legitimate concerns and become the beginning of reflection on the safety standards for using electric vehicles that should accompany their development. This article reviews electric vehicles in mining works. Concerns for the development of these technologies have been identified. Particular attention was paid to the concerns about the operational safety of electric vehicles in the mining environment.
Streszczenie. Pojazdy akumulatorowe stają się szansą na zrównoważony rozwój w górnictwie. Zalet pojazdów elektrycznych w górnictwie jest kilka,przede wszystkim związanych z poprawą bezpieczeństwa warunków pracy górników. Dla górników istotne jest, że pojazdy elektryczne nie są znaczącym dodatkowym źródłem ciepła, redukują emisję spalin w środowisku ich użytkowania oraz charakteryzują się bardzo małą emisją szkodliwych gazów lub całkowitym ich brakiem. Obecnie przemysł wydobywczy rozwija kilka inicjatyw na rzecz zrównoważonego rozwoju, skupiając firmy górnicze, dostawców i instytucje badawcze w celu przyspieszenia rozwoju technologii i jak najszybszego wdrożenia pojazdów typu BEV (battery electric vehicles) w górnictwie. Działania te są akceptowane przez górników, choć jak każda nowoczesna technologia budzą uzasadnione obawy i stają się początkiem refleksji nad normami bezpieczeństwa użytkowania pojazdów elektrycznych, które powinny towarzyszyć ich rozwojowi. W artykule przedstawiono przegląd pojazdów elektrycznych w pracach górniczych. Zidentyfikowano obawy dotyczące rozwoju tych technologii. Szczególną uwagę zwrócono na obawy dotyczące bezpieczeństwa eksploatacji pojazdów elektrycznych w środowisku górniczym. (Pojazdy elektryczne w górnictwie w aspekcie bezpieczeństwa ich użytkowania)
Keywords: electric vehicles, operational safety, mining. Słowa kluczowe: pojazdy elektryczne, bezpieczeństwo, górnictwo.
Introduction
Access to ore in mined mines becomes complex over time. As a result of the exploration, deposits are located more profoundly, and their quality is deteriorating. That brings in the need to employ more and more mining vehicles, which account for an average of 50 per cent of the mine’s total direct emissions [1]. However, traditional diesel vehicles (DV), commonly used in mines, have several disadvantages. [2] indicates that diesel vehicles in mining have low efficiency (35%), low overload capacity, high maintenance cost, require skilled mechanics for maintenance, are noisy (~105 dB), can cause fog formation, and generate high heat. Moreover, in the aspect of development, they are difficult for data gathering, remote monitoring and building autonomously. Also, there is an impediment in fuel transportation for DV in deep mines.
As a result of numbered issues with DV, some sustainability initiatives within the industry, mining companies, vendors and research institutions to support innovation and haste the adoption of new equipment, including BEVs, have been started. For example, in European Union, a project was financed as part of the activities of the Horizon 2020 program. The project’s name was SIMS from Sustainable Intelligent Mining Systems. The project was carried out by a consortium of mining companies, equipment and system suppliers to top-class universities. However, this initiative had a few goals [3]:
● automated planning and reporting of mining progress through ground control to improve event planning (a digital twin), improve results and improve safety in production, ● battery electric vehicles implementation and testing in the operating mines, ● development of training modules for operators and mine workers and educational modules for students and the general public, ● communication and positioning – development and testing in operating mines.
Enterprises involved in the project include KGHM Poland, K + S Germany, Boliden Sweden, Lulea Sweden, Agnico Eagle Finland, LKAB Sweden, ABB, Epiroc, Ericsson and Mobilaris.
Another example of a sustainable mining initiative is International Council on Mining and Metals (ICMM), a global leadership organization for sustainable development. It has 37 association members and 26 Company members (currently). As the official website introduction says [2]: the primary goal of the organization’s Innovation for Cleaner, Safer Vehicles (ICSV) initiative is to enable its members the meeting in a non-competitive space. Such an environment can create conditions for the world’s largest original equipment manufacturers (OEMs) to accelerate the development of a new generation of mining vehicles and improve existing ones. In addition, the program focuses on motivating and encouraging activities directed at project participants to encourage them to find the advantages of the electrification of mining vehicles [4].
The result of such initiatives is electric vehicles being gradually introduced into the mines. Their design and operating conditions depend on the intended use and the mine (open-cast, underground) in which they are used. Notwithstanding the many advantages electric vehicles carry in mines, their emergence creates new risks and concerns for use. The previous pilot projects and the first attempts to use this type of vehicle have allowed identifying potential problems that may arise from introducing electric vehicles to the mine.
Electric Vehicles in mining
Undoubtedly, regardless of the technology used, electric vehicles have numerous advantages over diesel vehicles traditionally used in mining [5]:
● higher energy efficiency (about 90%); ● constant torque (including high torque at low speeds), ● quick response to the load and better overload capacity, ● no exhaust fumes and therefore no mine air pollution and no fog formation, ● generate only a third of the heat emitted by a diesel having the same power ● hourly electric energy cost lower than hourly fuel cost for diesel, ● less maintenance required, ● low noise and vibration level.
The dynamic development and increased interest in battery electric vehicles in mining have been visible for the last ten years. However, other solutions are available for a much more extended period. Nonetheless, vehicle manufacturers already offer a wide range of electric vehicles for various mining activities. As shown in Table 1, mines can choose from: electric rope shovels, Electric Load-Haul-Dump (eLHD) trucks, Electric Haul Trucks, Electric Drills, Electric Service Vehicles, electric crushers, Electric scoops, boomer and smaller trucks, Electric locomotives, Battery-electric explosives charger, Rock bolting rigs and conveyors. However, they differ in the used technology of batteries and charging systems. In addition, design and operational considerations vary for different equipment types. For example, tethered equipment typically requires accommodations for the cable, while trucks might focus more on regenerative braking. [6]
First can be mentioned electric vehicles used in 1975 like electric rope shovels, powered by the power grid. However, the need to power the cable from the mains may cause damage to the cable, electric shock hazards, and vehicle downtime. Moreover, the vehicle’s operating range is limited due to the cable length. Therefore, this technical it is impractical for trucks, so not many vehicles have been commercialized [5]. Since these vehicles do not need refuelling, what makes them time efficient.
Another solution, used in mines for over a hundred years, represented by, e.g. Electric Haul Trucks by ABB and Caterpillar (see Tab.1), is trolley-powered equipment. This technology powers electric rail or trackless vehicles from an overhead cable. It is impractical but creates an attractive alternative for mine trucks, particularly those working on long ramps (up to a few kilometres) [5]. The modernization and development of this technology is BluVein. The system is based on a slotted power rail set down into a public highway. The conductors are not exposed, so it is safe for people, animals and vehicles to pass over it. Electric trucks drive over the rail at 80 or 100 kph, automatically deploying an arm connecting to the rail. The truck can then draw electricity to power itself and charge its battery for later use [7]. The benefits of this solution are eliminating battery replacement, removing downtime for charging, or the possibility of using smaller batteries [8]. However, attention-grabbing, the technology is under development and will be installed in 2022 for a six-month co-trial with the various mines.
Through the current advances in battery technology, since 2016 become possible to manufacture reliable battery electric vehicles (BEVs). These can be used in all mining methods. Also, those requiring regular movement between working levels, such as sublevel stop, cut and fill, small/medium-scale sublevel caving, and room and pillar, can operate on average mine roads. [9] Generally, battery electric vehicles, due to the charging technology, can be divided into [6]:
● On-Board Charging, ● Off-Board Charging of On-Board Batteries, ● Off-Board Charging of Off-Board Batteries (Battery Swapping), ● Hybrid Charging Method, ● Off-Board Proprietary Chargers, ● Alternative Charging Systems and Equipment Types (Overhead Catenary Systems Or Trolley Assist and Charge-While-Operating (Tethered) Electric Equipment
Table 1. Electrically/battery-powered machinery (based on [1], changed with updates)
.
According to research studies [10], BEV makes it possible to reduce the downtime of diesel vehicles despite the need for loading. Also, modern solutions like those used in the Rock bolting rig by Sandwig enable battery charging during, e.g. drilling.[11]
Problems identified for EV development in mines
Problems defined by literature can be generally divided into four main groups: safety, operational, infrastructure, and global issues. From the user’s point of view, operational issues are the most disturbing everyday work. Those make their work inconvenient and inefficient. For example, miners point to the necessity of battery charging as their primary concern with BEV [9]. Also, mining staff for the safe operation of BEV needs additional training and, in some cases, changes in competencies [12]. Skills with growing demand include system evaluation and analysis, mathematics, active listening, instructing, data analysis, data and digital literacy, and judgment and decision-making [12]. Skills with decreasing demand include vehicle operations, materials extraction, operations and control, equipment maintenance and blast-hole drilling [12].
An inconvenience in the extensive use of electric vehicles is the need to adapt the infrastructure. The unique infrastructure like a charging room or a system for battery charging is indispensable for battery charging [4]. Space and infrastructure are needed to test, maintain, discharge, charge, and store batteries [6]. In addition, chargers must meet requirements for operating under the ground, with specific temperature and humidity, and the need for power supply from the electrical system available in the mine. It is necessary to avoid temperatures above 30 degrees [13] and under 0 degrees [14], the same as frequent fast DC high power charging mode [15]. Also, according to [16], battery modules’ voltage should be tested, and used modules should be replaced to ensure long-term and reliable operation. . In systems like BluVein, the whole infrastructure of slotted rails is needed. Therefore, introducing electric vehicles to mines is easier in the case of newly created mines, including electric vehicles already at the design stage.
Of course, BEVs also bring general concerns like materials like lithium, cobalt, and copper accessibility to manufacturing batteries in the future. Another problem is battery utilization. Those problems might become significant with BEV popularisation.
However, a thing of the most significant concern is electrical safety. Safety issues may be connected with a few safety matters. First can be mentioned situations during normal operational conditions. Mining workers designated [9] possible accidents which may occur because of too quiet work of BEV. Miners used to louder conditions may be victims of car hits and similar accidents. They may not be aware of Bevs’ presence in their vicinity. Also, the risk of electrocution raises concerns. People traditionally using diesel mining equipment are often not trained to work with electric vehicles. They are afraid of electrocution, especially periodically performed maintenance operations.
Most safety concerns are connected to batteries. While the charging process. During the charging process, the battery may overcharge, which may damage the battery. Workers are concerned about the risk of electric shock if the battery needs to be replaced. Research [16,17] shows that both, the environmental conditions and the method of charging, are significant for the functioning of the battery. Also, battery systems under the ground are exposed to the traditional hazards of such systems under normal operating conditions. These are identified by [18] as after-accident ignition, electric shock due to the energy remaining in the batteries, and re-ignition due to energy not being discharged. The problem is that those situations under the ground are even more dangerous and hard to handle.
A significant impact on the safety of the charging process also has communication. Regarding safety, communication protocols are exposed to various information security threats, including natural elements (natural disasters, poor communication locations, deterioration of equipment performance) and human elements (destruction, fraud, theft, human lack of skills, malicious network attacks). In the event of communication errors, the electric vehicle may not be charged. Also, the charging process may be interrupted (which affects the efficiency of operation) or overcharged, which may even result in the self-ignition or explosion of electric vehicles and charging devices. [19]
Requirements for BEV users in mining
Due to the novelty of the topic and the lack of widespread use of electric vehicles in mining, unfortunately, there are no clear guidelines regarding the requirements that this equipment should meet. Therefore, it is one of the barriers to the widespread use of EVs in mining. However, the requirements for vehicles should result from the hazards that may occur, and these are difficult to define only under simulation conditions. However, so far, there are only recommendations that should be met by electrical equipment.
Such recommendation is a document “Recommended Practices for Battery Electric Vehicles in Underground Mining” [6] issued by The Global Mining Guidelines Group (GMG). GMG is a network of representatives from mining companies, original equipment manufacturers (OEMs), original technology manufacturers (OTMs), research organizations and academics, consultants, regulators, and industry associations worldwide who collaborate to face the new mining industry challenges. The document defines, among other things, what threats can potentially be generated by the technologies used and what standards theoretically they should meet. Decisions on the admittance of products for use in mining plants in Poland, based on [20], remain in force of the mining plant decision-makers. Decisions regarding the operation of the mining plant should be based on the existing regulations and include natural hazards occurring in mining plants. Due to the lack of applicable standards, making such decisions may be limited and contribute to a slowdown in electrification in the Polish mining industry. The conclusions from the experiences of other mines in the world published, e.g. by GMG, might be helpful for the decision-makers.[6]
Most common safety issues may be generally divided into energy storage – batteries connected ones and those about charging systems. The charger must be well-matched with the energy storage type and chemistry used at the mine, respected for the applicable charging rate (slow or fast), and compatible with different conditions. The charging system enclosure/shell should also have the appropriate environmental protection rating (IP) according to the installation location. Additionally, the system needs to be monitored, so there are no open plugs. Finally, the charger installation should comply with local codes and undergo any necessary approvals or inspections.[6] Document concerning electric vehicles in Poland is [21]. However, it is not applicable because it defines charging stations as an element of the road public transport recharging infrastructure. Also, [22] does not apply to handling electrical equipment in mining, as it refers to the provisions of [20].
Because BEV batteries require frequent charging, exposure to potential hazards often occurs when personnel connect, operate, and disconnect the charging system. Currently, in repairing electric vehicles, the employee must have SEP qualifications up to 1kV. Due to the lack of regulatory requirements for using such vehicles in mining, similar requirements should be expected. Of course, the rights do not guarantee knowledge about handling batteries and electric vehicles with such a specific structure.
Therefore, one should expect the necessity to undergo training to operate the device’s battery during its regular operation. It remains open questions. Who should conduct such training? Should it end with obtaining the appropriate certificate and which employees should be trained – replacing/charging the battery or all vehicle users or working in its vicinity? Due to [20], decisions must be considered within a given mining plant.
Recommendations
Before implementing electric vehicles, the risk assessment should be considered [23]:
● financial risks (e.g., increased infrastructure capital expense, early battery replacement) ● production risks (e.g., discharged vehicle recovery, production rate impact) ● health and safety risks (e.g., fire/explosion, electric shock, arcing fault) ● environmental risks (e.g., worn battery skulls toxic to the environment)
It is important to know why and where BEV will be needed, what is required and what type of equipment is necessary, and who is or should be trained to operate, maintain service and implement emergency procedures. [23]
Protection of equipment and installation should meet appropriate standards responding to the operational conditions (temperature, humidity and others). Excess dust, corrosion, condensation, water or other liquids should be eliminated to reduce the risk of accidents. Behalf of safe working conditions should be specified, required and applied proper maintenance and proper tools (Insulated tools). For the safety of users, battery training should be required. It is required to specify who should be responsible for the replacement of the battery, what conditions should be ensured so that such replacement is also safe underground, what means of protection should be provided to such a person, and what the procedure for admitting to work should be. This task is not easy because technology is still evolving. Training should focus on different user groups, such as Electricians, Service mechanics, and mechanical/electrical specialists. A training checklist for BEV mining vehicles and mining charging systems should also be developed for specific equipment. [23]
Conclusions
At the moment of writing this article, there are no obligatory recommendations for electric vehicle use in mining. The applicable documents concern the general principles of using electric networks, using electric vehicles, and admission to work with voltage. However, the conditions in mines require a risk assessment each time when working with a specific electric vehicle, determination of potential risks and rules for handling the device to avoid electric shock. It is crucial in traditional mines, the existing infrastructure of which is not adapted to using electric vehicles. Nevertheless, as indicated in the literature, despite the potential threats, electric vehicles in mining are its future and an opportunity for sustainable development.
REFERENCES
[1] Ertugrul N., Kani A. P., Davies M., Sbarbaro D., Morán L., Status of Mine Electrification and Future Potentials, Proceedings – 2020 International Conference on Smart Grids and Energy Systems, SGES 2020, 151-156. [2] International Council on Mining and Metals (ICMM) website https://www.icmm.com/, accessed 14.07.2022. [3] Sustainable Intelligent Mining Systems (SIMS) project website https://www.simsmining.eu/, accessed 14.07.2022. [4] Leonida C., Battery-electric Vehicles: Brightening the Mining Industry’s Future, Engineering and Mining Journal, 221 (2020), nr 1, 32-37. [5] Paraszczak J., Svedlund E., Fytas K., Laflamme M., Electrification of loaders and trucks – A step towards more sustainable underground mining, Renewable Energy and Power Quality Journal, Vol 1 Issue 12, 2014, 81-86. [6] The Global Mining Guidelines Group (GMG), “Recommended Practices for Battery Electric Vehicles in Underground Mining”, version 3, 2022 https://gmggroup.org/wp-content/uploads/2022/06/2022-06-23_Recommended-Practices-for-Battery-Electric-Vehicles-in- Underground-Mining.pdf, accessed 18.07.2022. [7] Sprague T., Miners Lead the Charge For Battery-electric Vehicles, Engineering and Mining Journal, 2022, nr 1, 26–30. [8] https://bluvein.com/about-us/, accessed 17.07.2022. [9] Halim A., Lööw J., Johansson J., Gustafsson J., van Wageningen A., Kocsis K., Improvement of Working Conditions and Opinions of Mine Workers When Battery Electric Vehicles (BEVs) Are Used Instead of Diesel Machines — Results of Field Trial at the Kittilä Mine, Finland, Mining, Metallurgy and Exploration, Vol 39, (2)2022, 203–219. [10] Nieto A., Schatz R.S., Dogruoz C., Performance analysis of electric and diesel equipment for battery replacement of tethered LHD vehicles in underground mining. Mining Technology: Transactions of the Institute of Mining and Metallurgy, Vol. 129, (1)2020, 22–29. [11] DS412iE ROCK SUPPORT DRILL RIG manual file:///C:/Users/wikto/Downloads/ds412ie-specification-sheetenglish.pdf, accessed 17.07.2022. [12] EY, Will electrification spark the next wave of mining innovation? Survey, 2019 https://assets.ey.com/content/dam/ey-sites/eycom/en_gl/topics/mining-metals/mining-metals-pdfs/eyelectrification-in-mining-survey.pdf, accessed 17.07.2022. [13] Ren, H. Hsu, R. Li, X. Feng and M. Ouyang, “A comparative investigation of aging effects on thermal runaway behavior of lithium- ion batteries,” eTransportation, Volume 2, 2019. [14] E. Wikner and T. Thiringer, “Extending Battery Lifetime by Avoiding High SOC,” Applied Sciences 2018, 8, 1825. [15] Tomaszewska, Z. Chu, X. Feng and S. O’Kane, “Lithium-ion battery fast charging: A review,” eTransportation, Volume 1, 2019, pp. 1-28. [16] Majek A., Niewczas A., Selected maintenance aspects of traction batteries in electric vehicles, 12th International Science-Technical Conference AUTOMOTIVE SAFETY, AUTOMOTIVE SAFETY 2020. Institute of Electrical and Electronics Engineers Inc. [17] Huang K., Wang Y., Feng J., Design of lithium-ion battery management system for mine electric vehicle. IOP Conference Series: Earth and Environmental Science, Vol. 680, (1)2021, 1-7. [18] Bisschop R., Willstrand O., Rosengren M., Handling Lithium- Ion Batteries in Electric Vehicles: Preventing and Recovering from Hazardous Events. Fire Technology, Vol.56, (6)2020, 2671–2694. [19] Jiang L., Diao X., Zhang Y., Zhang J., Li T., Review of the charging safety and charging safety protection of electric vehicles, World Electric Vehicle Journal, Vol.12, (4)2021, 1-24. [20] Ustawa z dnia 9 czerwca 2011 r. – Prawo geologiczne i górnicze Dz.U. 2011 nr 163 poz. 981. [21] Ustawa z dnia 11 stycznia 2018 r. o elektromobilności i paliwach alternatywnych Dz.U. 2018 poz. 317. [22] ROZPORZĄDZENIE MINISTRA ENERGII 1 z dnia 28 sierpnia 2019 r. w sprawie bezpieczeństwa i higieny pracy przy urządzeniach energetycznych Dz.U. 2019 poz. 1830. [23] Mayhew Performance Ltd., How to Manage Risks of Implementing BEV in an Underground Environment, Virtual Symposium: Battery Electric Vehicle Safety in Mines, Jan 25 2021. https://youtu.be/0xl1QAndTU4, accessed 18.07.2022.
Authors: dr inż. Wiktoria Grycan, Politechnika Wrocławska, Katedra Energoelektryki, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, E-mail: wiktoria.grycan@pwr.edu.pl;
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 98 NR 12/2022. doi:10.15199/48.2022.12.27
Published by Samhar Saeed Shukir, Electrical Department, Technical Institute- Kut, Middle Technical University, Baghdad, Iraq. Corresponding Author: samharalwandi@gmail.com
ABSTRACT
Solar power has numerous benefits, it is a clean and renewable energy resource that can help us to reduce carbon emissions from fossil fuel use and mitigate climate change. However, solar energy production is limited to daytime hours when sunlight is abundant, and for solving the intermittency problem batteries bank has been used, where it store electricity for later use, so you can keep appliances running during a power outage, and use more of the solar energy that you produce at your home. Solar batteries are a deep cycle batteries, as the current flows from the battery in small quantities and evenly. This article represents; difference between automotive batteries and a solar batteries, a brief explanation of the different types of solar batteries and a comparison between them in terms of price, depth of discharge , service life, charge and discharge temperature, and energy density. The article also introduces an electrical representation of the battery, criteria that are taken into account when choosing the appropriate battery such as battery capacity, battery efficiency, depth of discharge of the battery, the time required for charging the batteries, and connect batteries in series and in parallel, where it is necessary to know this information to choose the appropriate battery for designing the solar systems.
Keywords: Flooded batteries, Gel batteries, AGM batteries, Lithium batteries, Electrical models of batteries, Battery energy, Series and parallel connection of batteries
INTRODUCTION
Automotive batteries also known as starting, lighting, and ignition (SLI) batteries have a very low internal resistance (50 milliohm) to produce a burst of energy. Low internal resistance is achieved by adding extra plates and the lead is applied in a sponge-like form that has the appearance of fine foam for maximum surface area (Figure 1). The plates are thin (1mm), which make the discharge is short
Figure 1: Starting battery
The deep-cycle batteries have an internal resistance that is ten times that of the automotive batteries which is achieved by making the lead plates thick (figure 2). These batteries are characterized by a maximum capacity and a high cycle count, and this makes it ideal for solar energy systems.
Figure 2: Deep-cycle battery
Solar Batteries are a deep cycle batteries used to store the direct current generated by the solar panels, which is converted into alternating current by the inverter to operate the various loads. The battery (12V) generally consists of (6) cells, each of these cells consists of, anode, cathode, and the conductive material (the electrolyte).
There are many types of solar batteries (figure 3), which differ among themselves in the materials from which the anode and cathode are made and the type of electrolyte.
Figure 3: The different types of solar batteries
The most common types of solar batteries are:
1 – lead-acid batteries that include: • Liquid lead-acid batteries (flooded) • Gel Batteries • AGM batteries 2- Lithium batteries
The flooded batteries
It is the oldest type of batteries, the cheapest and the most widespread. It is called “liquid” because the conductive material between the anode and cathode plate is a liquid substance, which is sulfuric acid diluted with water, concentration ratio 3:1. Flooded batteries need maintenance, which includes replacing the acid and adding distilled water once or twice a month to compensate for the water evaporating from the batteries. Figure 4 demonstrates the components of a single cell of a flooded battery, which consists of sponge lead which represents the cathode electrode and a clip of lead, and behind the clip a plate of dioxide Lead, which represents the anode electrode, and these cells are immersed in acid diluted with water.
Figure 4: The liquid lead-acid battery
The gel battery
A gel battery has the same design and functionality as a traditional flooded battery. The gel battery differs from the liquid battery in that the conductive material contains silica in the electrolyte, which creates a gel-like substance. The gel battery is characterized by being suitable for use in many positions due to its stability and absence of any gases emitting from it, and it is a deep cycle battery.
Figure 5: The Jel battery
The AGM battery
A fiberglass material is placed between the anode and the cathode, which absorbs the electrolyte like a sponge and prevents it from leaking or evaporating. An AGM battery is a deep cycle discharge with the provision of mixing the sulfate back into the hydrogen gas, resulting in a reduction of the hydrogen released during the discharge process.
Figure 6: The AGM lead battery
The lithium battery
An anodes consist of graphite-based materials due to the low cost, wide spread, and the stability to accommodate the lithium insertion, but it carbon suffer from a low capacity, so in recent year, the carbon-based anode has been improved, and new types of anode materials, such as silicon, alloy, and metal oxides have been developed, which has improved the lifetime, capacity and performance of lithium batteries. Cathodes consist of a complex lithium compound material, such as LiCoO2 and LiFePO4 . Battery performance significantly differs with different cathodes. Cathode has been fabricated from lithium material blending with conductive material such as carbon due to low impedance because of high diffusion coefficient and high ionic conductivities compared with other materials compound. The electrolyte in lithium batteries includes three types liquid electrolyte, semisolid electrolyte, and solid-state electrolytes. Liquid electrolyte consists of lithium salts such as., LiBF4, LiPF6, LiN(CF3SO2)2, and LiBOB, which are dissolved in organic carbonates such as, ethylene carbonate, propylene carbonate, ethyl methyl carbonate, dimethyl carbonate, and their mixtures. While, the semisolid electrolyte, and solid-state electrolyte are composed of lithium salts as the conducting salts and high-molecular-weight polymer matrices such as, polyvinylidene fluoride and poly(ethylene oxide).
Figure 7: Lithium-ion battery
Table 1: Comparison of different types of batteries
Lead-acid battery
Jel battery
AGM battery
Lithium battery
Maintenance
Need
No need
No need
No need
Depth of discharge
50%
75%
50%
80%
Lifespan
3-5 year
6-8 year
6-8 year
20 year
Cost
150$
300$
250$
2000$
Charge temperature
-0°C to 50°C
-20°C to 50°C
0°C to 50°C
-0°C to 45°C
Discharge temperature
-30°C to 70°C
-40°C to 60°C
-20°C to 60°C
-20°C to 60°C
Storage temperature
-20°C to 60°C
-40°C to 60°C
-20°C to 60°C
-20°C to 60°C
Energy density
30W .h/kg
40W .h/kg
50W .h/kg
50-260W .h/kg
.
The electrical representation of the battery
To determine the power losses and the terminal voltage of the battery an electrical representation has been achieved by models based on thevenin network. The most simple model consists of a series resistor, RC network to describe basic charge transfer phenomenon, and open circuit voltage (Voc) which dependent on the state of charge (SOC) as obvious in figure 8(a). An enhancement for the batteries simulation can be done by adding a second RC branch as demonstrated in figure 8(b). The first RC branch represents short-term transient behavior, and the second RC branch represents long-term transient behavior
The coefficients K0, K1, K2, K3,…….,K14 depend on the respective cell type and are subjects of measurements.
For higher accuracy another RC network is proposed, in order to describe finally short- term, mid-term, long-term transient behavior. However, this makes the calculation of the associated capacitors and resistors much more complex, also studies have shown that 2RC model achieves good results, therefore it is proposed in simulations of electrical power grids
The most important information about batteries
The effectivity and performance of the battery depend on the following parameters:
1. Capacity of battery 2. Efficiency of battery 3. Depth of discharge
Battery capacity
The amount of energy that the battery can storage.
If a battery of (12V) has a capacity of (500 A.h) ,the energy can be storage with this battery is:
Energy = Voltage * Current * Time = 12V * 500A.h = 6000w.h
Battery efficiency
It is the ratio of the output energy from the battery to the input energy that the battery needs to charge.
If the energy that the battery needs to charge is (6000 wh) and the energy that can be obtained from this battery is (4800 wh), then the efficiency of this battery is:
It is the amount of capacity that can be obtained from the battery capacity.
If the depth of discharge is equal to 50% for a battery whose capacity is (60Ah), then the amount of capacity that can be get it from this battery is:
= 60A.h * 0.5 = 30Ah
The time required for charging the batteries
When the solar panels used to charge the battery, the time required for charging the battery is equal to (capacity of the battery / panel current)
If the panel(9A) used in charging the battery (200A.h) then the time that required to charge the battery = 200A.h. / 9A = 22.22h
Series and parallel connection of batteries
The batteries are connected in parallel or in series to obtain the required current and voltage
Figure 9 shows four batteries each one of (12V , 100Ah) connected in series and figure 10 obvious these four batteries connected in parallel.
Figure 9: Series connection of batteries
Figure 10: Parallel connection of batteries
CONCLUSION
At the present time, due to the rise in temperatures over the past years, it is necessary to take into account the impact of temperatures on the performance of the battery when choosing the appropriate battery for working on design. Temperature, have a significant effect on the performance, and the safety of the solar batteries. As the temperature of the battery increases the chemical reactions inside the battery also quicken, and increased storage capacity of the battery. It was found that an increase in temperature from 25°C to 45°C led to a 20% increase in maximum storage capacity, but an available capacity decreases over time, and the lifecycle of the battery is decreased over time. Lithium battery has better volume and weight, and is relatively cheaper to maintain but the initial cost is higher, and it is more temperature sensitive. Flooded batteries and Gel batteries are the most using in Iraq because they are more cost-effective, it’s price is just 1/4~1/6 of the lithium battery cost with an acceptable limits of the discharge depth (DOD) and it is suitable for high temperature work.
REFERENCES
1. Ji, L., Lin, Z., Alcoutlabi, M., & Zhang, X. (2011). Recent developments in nanostructured anode materials for rechargeable lithium-ion batteries. Energy & Environmental Science, 4(8), 2682-2699, Available at https://pubs.rsc.org/en/content/articlelanding/2011/ee/c0ee00699h/unauth 2. Xiong, J., Pan, Q., Zheng, F., Xiong, X., Yang, C., Hu, D., & Huang, C. (2018). N/S co-doped carbon derived from cotton as high performance anode materials for lithium ion batteries. Frontiers in chemistry, 6, 78, DOI: https://doi.org/10.3389/fchem.2018.00078 3. Shen, X., Tian, Z., Fan, R., Shao, L., Zhang, D., Cao, G., … & Bai, Y. (2018). Research progress on silicon/carbon composite anode materials for lithium-ion battery. Journal of Energy Chemistry, 27(4), 1067-1090, DOI: https://doi.org/10.1016/j.jechem.2017.12.012 4. Tremblay, O., & Dessaint, L. A. (2009). Experimental validation of a battery dynamic model for EV applications. World electric vehicle journal, 3(2), 289-298, DOI: https://doi.org/10.3390/wevj3020289 5. Divya, K. C., & Østergaard, J. (2009). Battery energy storage technology for power systems—An overview. Electric power systems research, 79(4), 511-520, DOI: https://doi.org/10.1016/j.epsr.2008.09.017
Published by Electrotek Concepts, Inc., PQSoft Case Study: Concrete Facility Harmonic Evaluation ASD Drive Trips and Transformer Fires, Document ID: PQS0503, Date: March 31, 2005.
Abstract: A Kiln ID fan drive (12 pulse rectifier) powers a 3000 HP medium voltage (4kV) motor. The associated harmonic filter periodically becomes overloaded and trips the corresponding 4kV breaker. The associated isolation transformer caught on fire within the first three months of operation. There have also been problems with the power factor correction capacitor banks.
The case study presents a summary of a harmonic evaluation that was performed before the plant substation was upgraded.
EXECUTIVE SUMMARY
Electrotek Concepts performed a site survey at the concrete facility from October 2 – 3, 2000. Measurements show that the harmonic filters installed at the Kiln ID Fan Drive (also known as the 21 Fan Drive) are not designed for operation with the current system configuration.
The site survey, measurements, and simulations show that there are some things that the customer can do to improve the reliability of the 21 Fan Drive. Electrotek recommends that the Kiln Main Drive be supplied from a new feeder. Supplying the 21 Fan Drive and the Kiln Main Drive from different feeders will lower the current into the 21 Fan harmonic filters and will increase the reliability of the process.
The 11th harmonic filter should be detuned also if it has not been. Calculations show that using the 105% taps on the 0.83mH filter reactors will decrease the current into the 11th harmonic filter.
The customer could improve the uptime of the 21 Fan Drive and the plant process by serving each filter through a dedicated breaker and removing the interlocks between the filter overloads and the main breaker.
Electrotek recommends that the customer operate with one 2400 kVAr capacitor bank step on-line.
Electrotek recommends that the old 1800 kVAr capacitor bank should be converted to a 2000 kVAr 5th harmonic filter – the filter be tuned to 297 Hz. This recommendation does improve on all of the other recommendations, but it may not be necessary after the Kiln Main Drive is supplied from a new feeder. Electrotek suggests that the customer implement the other recommendations and evaluate the operation of the 21 Fan Drive and the harmonic filters. The evaluation should include measurements at the 21 Fan harmonic filters for at least one week. The evaluation may show that the investment in a 5th harmonic filter may not be cost effective.
A harmonic evaluation should be performed before the plant substation is upgraded or before major equipment or system changes are made.
INTRODUCTION
The customer manufactures cement for use in the construction industry. Limestone (chalk) is mined and processed with other raw materials at the plant to create the cement.
The Kiln ID fan drive (Allen-Bradley 12 pulse rectifier) powers a 3000 HP medium voltage (4kV) motor. The associated harmonic filter periodically becomes overloaded and trips the corresponding 4kV breaker. The associated isolation transformer caught on fire within the first three months of operation. There have also been problems with the power factor correction capacitor banks.
Measurements show that the harmonic filters installed at the Kiln ID Fan Drive (5th, 7th and 11th) are not designed for operation with the current system configuration. Recent operating experience has shown that each of the three filters has tripped the above-mentioned 4 kV breaker. The Kiln ID fan drive and the Kiln Main Drive (600 hp DC motor) are currently fed from a common feeder.
The facility also has many other sources of harmonics including about 2000hp of 6 pulse drives. It is possible that the eleventh harmonic filter mentioned above, in combination with other power factor correction capacitors, resulted in a new resonance near the fifth or seventh harmonic that was excited by some of these other loads.
The harmonic problem seems to be less prominent when both finish mill (3700 hp synchronous) motors are running and when the power factor correction capacitors are in service.
An Allen-Bradley representative has reviewed the situation and has concluded that the problems are due to high levels of “pre existing” harmonics on the drive feeder bus. The source of those harmonics is thought to be from various low voltage 6-pulse drives (total amount about 2000 hp).
FIELD MEASUREMENTS
Measurements were performed at most of the 4160 volt feeders. Figure 1 shows a simplified one-line diagram for the plant electrical power system. The feeder current measurements were performed in the main switchgear room at the existing current transformers. The bus voltage for these measurements is the voltage measured at the potential transformer secondaries in the Incoming power cabinet.
The measurement snapshots show the three-phase voltage and current waveforms and the harmonic spectrum for the Phase A current. The Phase A voltage spectrum is shown with the Incoming measurement snapshot.
Figure 1 – Electrical Power System One-line
Incoming
Figure 2 – Incoming Measurement Snapshot
Finish Mill #1 Main Drive
Figure 3 – Finish Mill #1 Main Drive Measurement Snapshot
Finish Mill #2 Main Drive
Figure 4 – Finish Mill #2 Main Drive Measurement Snapshot
Roller Mill ID Fan
Figure 5 – Roller Mill ID Fan Measurement Snapshot
Measurements were performed at the supply to the 21 Fan and each of the harmonic filters. In Figure 13, Phase A current is one phase of the 5th harmonic filter current, Phase B is one phase of the 7th harmonic filter current, and Phase C current is one phase of the 11th harmonic filter current.
Table 1 – Filter Current
60 Hz
Harmonic
Irms
5th
35
14
37
7th
25
18
31
11th
65
48
80
.
Table 1 shows a summary of the current measured at each filter. Filter current is characterized by the fundamental component and the harmonic component. The harmonic current in a filter is predominantly at the tuned frequency of the filter. The harmonic current in the 5th harmonic filter is 300 Hz current (5th harmonic), the harmonic current in the 7th harmonic filter is 420 Hz current, and the harmonic current in the 11th harmonic filter is 660 Hz current. The fundamental current into the filters will increase as the bus voltage increases.
Measurements at the capacitor banks show that the capacitors are filters to higher order harmonic current, like the 13th harmonic. Figure 12 shows the measurement snapshot of the capacitor bank current. 10 % of the capacitor bank current is 13th harmonic current. This occurs because low impedance is created by the parallel combination of the capacitor banks and the system inductance. The system inductance is dominated by the substation transformer reactance.
The power factor correction installed at the 400 HP Roller Mill ID Fan creates a similar situation. The current measurements at the Roller Mill ID Fan feeder show 13th harmonic current. Some 13th harmonic motor current is not necessarily harmful to the motor. Bus voltage distortion and operating experience are the best indicators of potential motor problems caused by harmonics. Harmonic voltage distortion begins to seriously impact motor life when it reaches 8% to 12%, or higher. Another reason to not be too concerned about the harmonic current in the Roller Mill ID Fan feeder is that 13th harmonic current is positive sequence current. Positive sequence current creates a field that rotates in the same direction as the field created by fundamental, 60 Hz, current. Negative sequence current (5, 9, 15 harmonic) is the greatest concern to motor operation
THDV with Different Capacitor Bank Configurations
Figure 14 THDV with Both Capacitor Banks On-line
Figure 15 – THDV with One Capacitor Bank On-line
A comparison of Figure 14 and Figure 15 shows that the high impedance caused by the parallel combination of the capacitor banks and the system inductance moves from near the 7th or 8th harmonic to somewhere closer to the 13th harmonic.
Figure 16 – THDV with No Capacitor Banks On-line
Figure 16 shows that the system parallel resonance has moved to a higher frequency between the 20th and 25th harmonic.
The measurements show that the normal capacitor bank configuration, both steps on-line, is the best configuration as far as minimizing bus THDV. It is not clear from the measurements how the capacitor bank configuration affects the 21 Fan harmonic filter current.
Figure 17 – Simulated System Impedance with different Capacitor Bank Configurations
Figure 18 – Kiln & Preheater Bypass Feeder Current
The chart of the Kiln & Preheater Bypass feeder current shows that the 13th harmonic current is highest with one capacitor bank on-line, it is lowest with no capacitor banks on-line. These results coincide with the system impedance evaluations and with the voltage distortion recorded during the different capacitor bank configurations.
13th harmonic current from the 21 Fan and from the Kiln Main Drive normally flows into the capacitor banks. The capacitor banks are filtering 13th harmonic current.
HARMONIC SIMULATIONS
Electrotek developed a power system model for the facility and the associated utility power system. The model is used to simulate harmonic voltage distortion and to evaluate power system impedance with respect to power system configurations and equipment.
Simulations were performed to evaluate solutions that focused on improving the reliability of the process by eliminating the overload of the harmonic filters at the 21 Fan. Simulations are also used to evaluate the impact that specific solutions have on the entire plant power system and if solutions introduce any operational restrictions.
The simulations show that the harmonic filters at the 21 Fan are providing harmonic current control for the 21 Fan Drive and the Kiln Main Drive. Operational experience has proven that the harmonic filters are not designed to control the harmonic current from any loads other than the 21 Fan Drive. Calculations show that the filter design for application at the 21 Fan Drive alone is questionable.
Basecase
The harmonic simulations performed with SuperHarm were verified with the measurements that were taken at the facility. Measurements are used to create the base case for the harmonic simulations. The measurements that represent the worst-case harmonic current injected into the power system are used to develop the base case model. The base case represents “normal” conditions – both capacitor bank steps on-line and the plant operating with both finish mills running. The base case simulations are compared with the measurements to verify the accuracy of the model.
The simulated THDV at the main 4160 volt bus is 1.22%.
Table 2 – Basecase Harmonic Filter Phase Current (amps)
Basecase – Present Configuration
Filter Current
Fundamental
Harmonic
RMS
5 h Filter
30.4
17.6
35.1
7 h Filter
22.3
16.1
27.5
11 h Filter
58.7
82.2
100.9
.
The table shows the phase current into each filter for the Basecase simulation. The results compare with the measured values.
5th Harmonic Filter at 4160V Main Bus
A common approach to controlling harmonic current is to install a passive harmonic filter (or multiple filters). Passive harmonic filters are normally implemented at a main bus or where the voltage distortion problems are being experienced. The implementation of harmonic mitigation depends on many other considerations, like – initial cost of mitigation equipment, installation costs, operation costs, maintenance, control of equipment, space requirements, impact on the power system impedance, impact on other equipment, voltage rise, and resulting power factor. Distributing harmonic filters throughout a facility is usually more expensive to implement than consolidating the control of harmonic current at a main bus. It is more difficult to evaluate and control the operation of filters distributed throughout a facility.
This case evaluated the system with a 1500 kVAr harmonic filter tuned to the 5th harmonic and a 2400 kVAR fixed capacitor bank. The idea is to utilize the fixed capacitor bank for power factor compensation and it also filters higher order harmonic current like the 13th harmonic. The new 5th harmonic filter would limit the amount of harmonic current into the 21 Fan harmonic filters from other nonlinear loads.
Table 3 – 21 Fan Filter Phase Current – 5th Harmonic Filter at 4160V Main Bus
5h Filter at Main Bus
Filter Current
Fundamental
Harmonic
RMS
5th harmonic
30.3
17.7
35.1
7th harmonic
22.2
14.3
26.4
11th harmonic
58.4
78.6
97.9
.
Table 3 shows the simulated phase current into each 21 Fan harmonic filter. The simulations show that installing a 5th harmonic filter at the main bus does not reduce the filter current during normal operation. The results suggest that the harmonic current into the filters from sources other than the 21 Fan and the Kiln Main Drive is normally very small.
New Feeder to Supply the Kiln Main Drive
Simulations were performed with a new dedicated feeder for the Kiln Main Drive.
Figure 19 – Kiln Main Drive Power
The figure shows the present configuration for the supply of power to the Kiln Main Drive and a simple one-line diagram showing a new feeder for the supply of power to the Kiln Main Drive. The Precipitator ID Fan and the Quench Fan should also be supplied from the new feeder.
Table 4 – 21 Fan Filter Phase Current – New Feed to the Kiln Main Drive
New Feed to Kiln Main Drive
Filter Current
Fundamental
Harmonic
RMS
5 h Filter
30.9
6.1
31.5
7 h Filter
22.7
5.1
23.3
11 h Filter
59.7
80.6
100.3
.
The table shows that there is a significant decrease in the harmonic current into the 5th and 7th harmonic filters when the Kiln Main Drive is fed from a dedicated feeder and not tapped off of the 21 Fan feeder. The reduction in rms current correlates to the reduction in harmonic current.
New Feeder and 5th Harmonic Filter at the Main Bus
Simulations were performed with a 1500 kVAr 5th harmonic filter installed at the 4160 volt bus and with a new feeder to the Kiln Main Drive.
Table 5 – 21 Fan Filter Phase Current – New Feeder and 5th Harmonic Filter
5h Filter at Main Bus & New Feed to Kiln Main Drive
Filter Current
Fundamental
Harmonic
RMS
5 h Filter
30.8
2.4
30.9
7 h Filter
22.6
3.0
22.8
11 h Filter
59.5
76.7
97.1
.
The simulations show that this solution results in the least amount of current in the 21 Fan harmonic filters.
The impedance between the Kiln Main Drive and the 21 Fan harmonic filters is increased when the Kiln Main Drive is supplied from a new dedicated feeder. The added impedance helps to decrease the harmonic current into the filters from the Kiln Main Drive. The 5th harmonic filter at the main bus limits the amount of harmonic current to the 21 Fan filters from other plant drives.
Frequency Scans
Frequency scans are performed to show system impedance as a function of frequency.
Figure 20 – System Impedance with 1800 kVAr & 2400 kVAr Steps
The figure shows that a parallel resonance exists between the 5th and 7th harmonic with both the 1800 kVAr and the 2400 kVAr steps on-line. Parallel resonances at characteristic harmonic frequencies (5, 7, 11, 13, etc.) should be avoided when applying power factor correction. The frequency scans also shows that a series resonance exists at the 13th harmonic when both banks are on-line.
Capacitor banks will often detune themselves during operation when a parallel resonance at a characteristic harmonic causes voltage to rise high enough to cause individual capacitor cans to fail. Capacitors will fail until the parallel resonance moves away from the characteristic harmonic. As cans fail, the parallel resonance will shift to higher frequencies in the spectrum. High harmonic current in capacitors can also cause them to fail.
Figure 21 – System Impedance with Original kVAr and Present kVAr
Figure 21 shows how the system impedance has changed from the original compensation of 4200 kVAr to the present. The system impedance does not seem to have changed much, but plant operation and system configuration will affect the outcome of the interaction between plant loads and the system impedance.
An increase in system voltage can be the difference between a capacitor failing or not when a parallel resonance exists at a characteristic frequency. Bus voltage will increase at night, during the weekend, and when large loads are secured, like one of the mills at the plant. It is not certain what scenario caused capacitors to fail.
Figure 22 shows the results of the frequency scan with the 1500 kVAr 5th harmonic filter at the main bus. The recommended filter creates a series resonance is at the 5th harmonic. Compensation is added to the remaining capacitor bank to increase the total compensation of the bank to 2400 kVAr. 2400 kVAr of compensation places the parallel resonance near the 9th harmonic.
Figure 22 – System Impedance with Recommended 5th Harmonic Filter
Harmonic filters at various harmonic loads
The harmonic filters installed at the 21 Fan were not designed for application at the cement facility. The filters appear to be designed for the control of harmonic current injected by the 12-pulse A-B drive and nothing else. It is difficult to successfully apply harmonic filters at different harmonic loads. It is even more difficult to apply filters at one of several harmonic loads.
Applying harmonic filters at the drive is theoretically appealing because it limits harmonic current to the source. There is no easy, reliable, or relatively inexpensive way to implement this option. In order to avoid overloading, the filters often have to be installed with isolating reactors to prevent the flow of harmonic currents from other loads. This increases the cost of the individual filter installations. It is apparent that the filters are absorbing harmonic current from the 600 HP Kiln Main Drive. The filters are connected very close to where the Kiln Main Drive feeder taps off of the main Kiln & Preheater Bypass feeder.
The impedance of the long feeder from the main 4160 volt bus to the 21 Fan may limit the filter harmonic current from other ac and dc drives in the plant. How much current in the filters is from other drives depends on how many steps of the capacitor bank are on-line and what plant loads are operating.
Harmonic filters are usually applied at the main bus level when there are several harmonic loads. Even if the A-B drive were the only nonlinear load at the facility, the filters should be designed for reliable operation with 1.0% to 2.0% THDV due to the utility supply.
RECOMMENDATIONS
1. Electrotek recommends that the Kiln Main Drive be supplied from a new feeder. The Precipitator ID Fan and the Quench Fan may be supplied from the new Kiln Main Drive feeder, also. Supplying the 21 Fan Drive and the Kiln Main Drive from different feeders will lower the current into the 21 Fan harmonic filters and will increase the reliability of the process. Performance of this recommendation may allow the client to forego the performance of Recommendation 5, the installation of a 2000 kVAr filter at the main bus. This is explained further with Recommendation 5.
2. The 5th harmonic filter and the 7th harmonic filter at the 21 Fan Drive have been detuned by utilizing the 105% tap of the respective filter reactors. The 11th harmonic filter should be detuned also if it has not been. Calculations show that using the 105% taps on the 0.83mH filter reactors will decrease the current into the 11th harmonic filter. This recommendation may be performed at any time.
3. The A-B 21 Fan Drive trips off-line when a harmonic filter overload trips because the harmonic filters do not have dedicated breakers to open and protect the filters. The same breaker serves as protection for the 21 Fan Drive isolation transformer and each filter. The company could improve the uptime of the 21 Fan Drive and the plant process by serving each filter through a dedicated breaker and removing the interlocks between the filter overloads and the main breaker. It makes sense to control what filters are on-line at the same time and there are filter combinations that should not cause the 21 Fan Drive to trip.
These filter configurations could be permitted during drive operation:
1. All three filters off-line. 2. 5th harmonic filter on-line. 3. 5th and 7th on-line. 4. 5th and 11th harmonic filters on-line. 5. 11th harmonic filter on-line. 6. All three filters on-line.
This recommendation may be performed at any time.
4. The amount of compensation that should be installed as a fixed capacitor bank is 2400 kVAr. The one-line drawing shows that one step of the capacitor bank used to be 2400 kVAr. This recommendation is to operate with one 2400 kVAr step on-line. 2400 kVAr is a good amount of compensation because the system parallel resonance is near the 9th harmonic. The 9th harmonic is acceptable because it is in between the characteristic 7th and 11th harmonics.
This recommendation can be performed at any time. It appears that this could be performed by company personnel and requires no material expense. Capacitors could be removed from the other capacitor bank (the 1800 kVAr bank) to increase the compensation of the 2400 kVAr bank back to its original value.
5. The old 1800 kVAr capacitor bank should be converted to a 2000 kVAr 5th harmonic filter. Electrotek recommends that the filter be tuned to 297 Hz. The recommended filter is designed with 4800 volt capacitors so the effective compensation of the filter will be about 1560 kVAr. The harmonic filter at the main bus will greatly reduce the amount of 5th or 7th harmonic current into the 21 Fan filters from other adjustable speed drives. The filter design specifications are included in the appendix at the end of the report.
This recommendation does improve on all of the other recommendations, but it may not be necessary after the Kiln Main Drive is supplied from a new feeder. Electrotek suggests that the company implement Recommendation 1 and evaluate the operation of the 21 Fan Drive and the harmonic filters. The evaluation should include measurements at the 21 Fan harmonic filters for at least one week. The evaluation may show that the investment in a 5th harmonic filter may not be cost effective.
6. A harmonic evaluation should be performed before the plant substation is upgraded or before major equipment or system changes are made. Examples of things that will need to be evaluated are:
– 1. System Impedance. Determine where the parallel resonance is that is created by the parallel combination of the 2400 kVAr fixed capacitor bank and the system inductance. The substation transformer greatly influences the system inductance and the resulting system impedance.
– 2. Determine the affect that new loads or a new substation transformer will have on the loading of the 5th harmonic filter, the 21 Fan filters, or the harmonic voltage distortion.
It is very important that this recommendation is applied. Electrotek will be happy to provide the company with advice on whether or not a harmonic evaluation or an engineering study needs to be performed. This advice is free of charge.
Appendix A: Filter Design Spreadsheets
RELATED STANDARDS ANSI/IEEE Std. 18-1980: IEEE Standard for Shunt Power Capacitors IEEE Std. 1159 – 1995 Recommended Practice for Monitoring Electric Power Quality IEEE Std. 519-1992: IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems
GLOSSARY AND ACRONYMS THD: Total Harmonic Distortion
Published by Marian NOGA1, Andrzej OŻADOWICZ1, Jakub GRELA1, Grzegorz HAYDUK1, AGH Akademia Górniczo-Hutnicza, Wydział Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej (1)
Abstract. The Building Automation Systems (BAS) fulfil an increasingly important role in buildings, especially commercial and public buildings. They are an essential element of the building management systems (BMS) organization, integrating all building infrastructure subsystems on the field level. This paper presents the concept of using BAS systems in organization of local energy and the media consumption measurement network, in view of the remote metering Smart Metering and Smart Grid implementation as well as emergence of so-called prosumers.
Streszczenie. Systemy automatyki budynkowej (BAS) spełniają coraz bardziej znaczącą rolę w budynkach, zwłaszcza komercyjnych i użyteczności publicznej. Są podstawowym elementem organizacji systemów zarządzania budynkami – BMS, integrując na poziomie obiektowym wszystkie podsystemy infrastruktury budynkowej. W artykule przedstawiono koncepcję wykorzystania systemów BAS w organizacji lokalnych sieci pomiarów zużycia energii elektrycznej i mediów, w perspektywie wdrożenia systemów zdalnego opomiarowania Smart Metering, inteligentnych sieci elektroenergetycznych Smart Grid oraz pojawienia się tzw. prosumentów. (Aktywni odbiorcy w systemach Smart Grid – aplikacje technologii automatyki budynkowej).
Słowa kluczowe: automatyka budynkowa, LonWorks, integracja, SmartGrid. Keywords: building automation, LonWorks, interoperability, SmartGrid.
Introduction
The electrical power systems need modernization and adaptation to new conditions of their functioning. First of all it is connected with growing energy demand, reducing system reserves and more and more popular using of renewable sources of energy. They are going to be connected to the power systems in different, random points, additionally with different power level. It brings changes into power distribution system and its load. Since it is important to implement more dynamic energy management in the power system as well as monitoring and improvement of power quality parameters. Information about the power level in the electric power system regions and changing energy demands is needed. These questions are base for the Smart Grid idea – the traditional power grid with some main power plants will be transformed into interactive, distributed power network. Power distribution in this kind of network will be depend on active consumers demand (demand data, energy consumption monitoring, different tariffs) as well as energy distributors and local generating points (wind turbines and PV panels farms etc.) The Smart Grid it is not only buzzword, but the first of all huge chance to improve energy efficiency, energy consumption minimization, appropriate energy management and power grid improvement. To put it simply, Smart Grid it would be hybrid of the energy distribution system and IT networks to provide bidirectional communication between all modern electrical power system subjects. The first element of this conception should be intelligent, remote measurement system of energy and other media consumption – Smart Metering. This kind of system contains: electronic, intelligent meters, data transmission infrastructure, database and management system with bidirectional, real-time communication [26]. Information from main and local power plants are transmitted to the individual and commercial consumers (supply parameters, energy quality parameters) and from consumers to the providers (power demand, failures, problems) [10,26,27]. This way classic consumer could be prosumer with possibility to active manage energy consumption (switch loads out of peak load/maximum demand; different tariffs) and produce and sale energy to the grid. Consumers are usually connected with different kinds of the buildings (houses, offices, industrial buildings, supermarkets, entertainment centers etc.). Very often they are equipped with IT infrastructure and more often building automation and BMS systems as well. It concerns especially public, office and commercial buildings [2,14].
Since it is very important and current question: to select tools and standards for Energy Service Interface (ESI) – software and hardware platform of communication and activity between prosumers, providers and producers in the buildings ESI could work as a part of the BMS or BAS (Building Automation System) system and in the houses as a part of the EMS (Energy Management System) or HAN (Home Area Network) networks [11,29].
Development of the Smart Grid is directly connected with implementation of new electric, electronic, automation and IT technologies as well as working out suitable directives, laws and standards. Progress in both fields should be systematic and simultaneous, especially taking into consideration current and binding directives and strategic programs accepted by the European Union.
Legal regulations
The question of the Smart Metering systems implementation was first time brought up in the European Parliament and of the Council Directives. First of them No. 2006/32/WE concern on energy end-use efficiency and energy services. it is state there that Smart Metering systems, with individual meters for each consumer, are one of the means to achieve energy efficiency in European countries. There are general regulations for measurements and energy savings verification there as well. The second one is Directive No. 2009/72/WE concerning common rules for the internal market in electricity. In this document the Smart Metering systems are mentioned as a tool to achieve main directive goals: creating competitive and safe electrical energy market with consumer protection [6]. The directive states that consumers should have access to their energy consumption data (consumer is owner of the data) and data should be available for energy providers (other regulations). This statement resulted in necessity to work out new regulations in the personal data protection field and data security in the IT and transmission systems as well as on the filed level (direct connection between devices and meters in the automation systems) [29]. In the Directive there is on very important thread – in Annex I it is stated that each country implementation of the Smart Metering systems for the electrical power supply may be subject to an economic assessment of all the long-term costs and benefits to the market and the individual consumer or which form of intelligent metering is economically reasonable and cost-effective and which timeframe is feasible for their distribution. Such assessment shall take place by 3 September 2012. Where roll-out of smart meters is assessed positively, at least 80 % of consumers shall be equipped with intelligent metering systems by 2020 [2,7]. To carry out mentioned assessment in Poland special team for the Smart Grid implementation questions have been appointed by the Minister of Economy at 6th of December 2010.
At the December 2011 this team have announced positive recommendation to implement intelligent measurement systems – Smart Metering in Poland. It resulted in preparing special new regulations to amended energy law (pol. Prawo Energetyczne) and obligate distribution network operator (pol. OSD – Operator Sieci Dystrybucyjnej) to install intelligent meters for all consumer to 31st December 2020 [25,28,33]. It is worth to emphasize that the team have proposed the Minister of Economy to withdraw from detailed analysis of cost-effectiveness of the Smart Metering implementation. The Member of Parliament and the chairman of a parliamentary committee for power and energy industry – Mr. Andrzej Czerwinski explains that preliminary assumptions to the Smart Grid law and implementing regulations had been prepared earlier and some pilotage installations had been implemented in Poland by different energy providers, so positive recommendation have been natural step in that situation [5,7,34]. The faster way to implement the Smart Metering idea have been opened. In April 2011 a law on energy efficiency was passed – it obligate entities operating in the energy industry to take action to improve the energy efficiency factor and obtain the so-called “white certificates”. However, from the point of view of the Smart Grids and Smart Metering concept development more important are legislative work of the Ministry of Economy, associated with the development of so-called Smart Grid Law within the amendment of the Energy Law. Main objectives of the mentioned amendment are [5]:
• Reducing peak demand for the power and ensure balance in the National Power System • Development of a competitive electricity market through introduction of billing based on the actual consumption profile with facilitation of change the provider • Provide information about the current energy and other media consumption • Limiting in electricity prices increases for end-user through the implementation of new competitive forces in the electricity market.
These objectives have been the subject of extensive sectorial and social discussion, undertaken in the relevant documents, among others by the President of the ERO (Energy Regulatory Office). In one of them the concept of the Smart Metering market in Poland is outlined, with indication of the different actors role and requirements for the Independent Measurement Operator. This name in the latest documents proposed by the Energy Regulatory Office has evolved to the following: Measurement Information Operator [35]. As already mentioned, particular concern is dedicated the customers who in the new concept of operation of the power system, will become the active players, with an appropriate level of independence and the right to dispose of the data on energy consumption and demand. The aware consumer should be able to choose their electricity supplier/provider and to sale energy produced from renewable sources – acting as a prosumer. Additionally, attention is drawn to the fact that modern Smart Grid systems should increase the safety and reliability of the whole power system and energy supply to the customers. It is assumed to introduce monthly billing for electricity, based on actual measurements of the short-term consumption [25,36]. Many of these aspects were also discussed in a study on the implementation of the Smart Metering in Poland [13], with detailed analysis of the objectives, costs and benefits of this process. According to the authors, the main objective of implementation is to meet the requirements of the European Parliament and of the Council directives and to ensure energy security, with the least social cost. Reference is made to the fact that intelligent energy system should be stable and better balanced, ensuring the full support of renewable energy sources (RES) connected to the power grid and improving power quality. It was also established several key functional requirements that should provide the smart grid system. Each is now considered as a separate issue: the availability of data in relation to privacy and protection of personal data; the choice of tariffs and energy suppliers in the light of competition in the energy market and the already mentioned issue of the energy sale to the system, in the perspective of a bi-directional meters implementation. There is emerging conflict of interests of different social groups, industry and market. It turns out that energy consumers are primarily interested in reducing bills and simultaneously suppliers and manufacturers – profit and market share maximization. From the industry point of view even more considerable conflict is the pursuit to stabilize and better balancing the power system form the producers side and the possibility to easy connect the renewable sources to the system from independent producers – prosumers side. These issues should be explicitly addressed in the new law and related regulations [13,28]. In current sectorial debate associated with the inevitable necessity of Smart Metering systems implementation, the two main trends are outlining. One, created around the position of the President of the ERO and the Distribution Network Operators (DNO). Second, generated on the basis of the advisory team of the Ministry of Economy findings and propositions for the New Energy Law. Experts point out the need to synchronize the activities and positions of these two trends. It would be prerequisite for the future development of a uniform system of the intelligent power grid, both in the field of instrumentation, control and information sharing [32].
Active consumers – prosumers
In all discussions about a legal for the development of Smart Metering, the questions of the need to activate consumers and carry out extensive public information campaigns are raised. Active consumers are key to the Smart Metering and the Smart Grid idea success. To activate them good information campaign is needed about benefits, possibilities, functionalities and requirements connected with smart meters installing. But even the best organized information actions will not bring desired results if they will not follow a specific (not necessarily large) the benefit for the consumers, which motivate them to engage in the idea of energy saving and improve efficiency. The Smart Grid and intelligent power grid will retain and use its enormous potential, only with the approval of the customers. While significant progress has been made in the efficiency and reliability of the energy system, largely due to the modernization of transport infrastructure network, changing customer behaviours and their demands, remains a very difficult, particularly if they are not convinced of the benefits awaiting them. There are different kinds of benefits [17,25]:
• Simplification of settlements with customers • Energy bills based on actual energy consumption • Ability to change and adjust power tariffs to the “profile” of the energy consumer • Increasing the efficiency of the power supply and distribution systems • Simplify the process of energy supplier changing • Increased protection of the so-called vulnerable customers (network performance monitoring) • Increase public awareness on energy consumption, effectiveness and savings.
But installation of smart meters it is not everything – it is the only necessary tool. It should be implemented market mechanisms in the energy sector as well – not only in sale for large industrial consumers and institutions, but also for the smaller, individual consumers. Only such action, including mentioned previously awareness-raising actions, should result in the involvement of them, encourage to rationalization of the energy consumption and invest in renewable sources. Otherwise, it may be that Poland will be in the same situation as some of European countries, such as Italy, where in recent years a large-scale smart meters installations have been introduced (about 40 million customers) and the social awareness of their possibilities and functionalities increased only about 5% to 10%. In this situation the smart meters capabilities are used mainly by energy suppliers to detect and eliminate energy theft and power system balancing [27].
Another question connected with consumer involvement is personal data protection. It is often emphasized by energy sector experts and the Inspector General for Personal Data Protection [5,13,38]. As it was mentioned before the energy consumption data of the consumer are his own. This issue does not seem to be discussed, but energy consumption data should be collected remotely by the provider or Measurement Information Operator. Therefore, it should be properly take into account in the energy supply contracts [11,36]. From the other side data from meters should be available for the consumers to browse them both directly and processed – reports, analysis, profiles of the energy consumption etc. The different concepts of that supplier-operator-consumer interaction are verified in the pilot projects and the existing smart metering systems in Europe. One idea is to provide customer specific portable modules with wireless communication to track current consumption and effects of different types of devices activation at different hours of the day (peaks, tariffs). Another idea is based on the use of modern mobile phones, tablets and television sets with corresponding applications, dedicated to communication in a local network HAN (Home Area Network called) by different standards such as Bluetooth, Wi-Fi or TCP-IP –Internet [12,16]. However, it seems that one of the best solutions, to simplify service and allow remote access to measured data is setting up of virtual consumer accounts on websites provided by the Measurement Information Operator. Many attempts are made in this field in Western Europe and the USA. This kind of websites offer wide range of possibilities to browse reports, analyses, current meter readings, tariff selection and energy charges in on-line mode. From the average consumer point of view these features allow self-control and verification of actions taken to improve energy efficiency. Good example in this field is website Google Power Meter provided by Google for one of the pilotage projects [1,9]. But the convenience of the use of such services is governed need to ensure a high standard of data security, control access and protect against unauthorized access attempts.
The active support of energy systems – key elements
Previously mentioned the active energy consumers are only one part of the planned active, dynamic power system – Smart Grid. The implementation of this idea requires a number of elements: support and data transmission organization between all elements of the system as well as modernization and installation of modern system that will be control power in the supply system, according to changing demands. This also applies to technologies, systems and infrastructure in buildings, which are among the most intensive consumers of electricity and heat. Around the world, the steps are taken to enable commercial and other buildings interact with smart electricity grids. These actions will allow the users to directly participate in the energy market, with increased emphasis on energy savings and improve power management. This concept is called the Building-to-Grid or B2G [11].
One of the emerging Smart Grid standards allowing buildings connection to the network is OpenADR (Open Automated Demand Response). OpenADR is an open and standardized method of communication signals about energy demand (called DR – Demand Response) [2,22]. This data is for the electricity providers, system operators and their customers and should be communicated by means of a common language with the use of existing network based on IP protocol, such as the Internet. It is worth noting that the number of buildings equipped with an Energy Management System (EMS) is increasing, so they are ideal platforms for the implementation of demand response energy consumption (OpenADR). Such objects can use or modify existing intelligent network control to accept signals from the OpenADR systems. With preprogrammed set of events, building automation system can reduce the load according to the messages received in real time and provide information about its use of energy back to the energy supplier and operator. To allow the EMS systems receive signals from the OpenADR will likely require software update or installation of additional equipment, the purpose of which will provide relevant information to the building management system [11]. One of the most critical issues is appropriate programing of energy control strategy in the EMS. This system must react accordingly depending on the message coming from the OpenADR, which can include information about the incident or the current and projected energy prices. For example, if the message contains information about the growth rate for electricity, building automation system can dim the lights or change the temperature settings to reduce the energy consumption – heating or HVAC system [10]. Leading organizations caring for distributed smart grid standards are actively involved in the development of Smart Grid system through several industry initiatives, including:
• The standards of building automation should be considered as a tool for the Smart Grid system realisation. The main objective of this process is to ensure that products comply with the standard can be used in many cases recommended for use in the smart power grid projects
• Adaptation of the standard to the B2G idea and the appropriate type of communication with the OpenADR. This process is designed to make the most effective use of the systems properties and ensure their mutual cooperation
• Mobilization of the operators, distributors, integrators and consumers, primarily to increase their awareness about the capabilities of the Smart Grid.
Building automation systems as part of the active customers infrastructure
So far, the building automation system integrators have been concentrated primarily on providing users with the appropriate comfort and safety in buildings. Thus, common functionalities and features in automated buildings include: lighting and lighting scenes and scenarios control, service of blinds and shutters in windows, HVAC control – thermal comfort, access control, monitoring of devices and subsystems operating parameters, monitoring and acquisition of events, cooperation with anti-theft and fire systems, etc. In larger buildings these functionalities are more and more integrated and implemented into a single building management systems – BMS. In this kind of the applications, building automation systems have been used for many years, and their functionality in this field is still improving. They are becoming more reliable, and users derive benefit from them more and more confidence. The purpose of installers and integrators of the automation and monitoring systems is to achieve such a state that users use them involuntarily and the building infrastructure devices perform their functions reliably and quickly. According to the AGH researchers building automation systems can be used at field level as a tool for monitoring and optimizing the electrical energy and other media (heat, gas, water) consumption. It could be achieved by introduction of integrated remote metering modules and control procedures as well as mutual interaction between the different subsystems installed in the modern buildings [20].
Pilotage and research installations – examples and case studies
Taking into considerations presented information and directions of building automation systems development, to implement them in the Smart Metering and Smart Grid applications, AGH scientists and research workers undertaken research in the field of the building automation systems used to perform tasks connected with implementation of the Smart Grids. At AGH in Krakow is conducted project: “Optimising energy consumption in buildings”, funded by the National Research and Development Centre (NCBiR). In this project have been implemented comprehensive systems of the electricity consumption metering in three buildings – one in the AGH Krakow campus and two in the office and commercial complex. One of the buildings is built as so-called energy-efficient, using the latest building and telecommunications technologies [10].
Define the parameters of the energy consumption of buildings analysed in the project, with different groups of receiving energy, have required proper metering. To achieve this, three systems of energy consumption monitoring have been developed, for all three mentioned types of buildings. The first one is educational and office pavilion B1 AGH from the 50’s of last century. Another one is a No. 6 building with traditional technologies located in Science and Technology Park Euro-Centrum (PNT) and the last one is energy-efficient building No. 7, also located within the PNT [20]. The most detailed metering installation is in the building No. 7 PNT. The monitoring energy consumption system has been developed and implemented using the existing supply network topology, including among others meters for: individual lighting circuits, computer and power sockets both for groups of rooms (some rooms for one tenant) as well as power circuits of technical infrastructure in the building, such as a heat pump, heat exchanger, chiller, central HVAC, elevators. Monitoring system has a tree structure, including the main meter, the meters in the floor cabinets and ultimately individual meters for groups of rooms. An important element of the monitoring was to develop a system of data acquisition, reading all the meters in a 5-minute periods, and designating the difference in readings (5-minute power/load). Additionally, if the meter allows the measurement of other parameters such as voltage, current, reactive power, they are also recorded in the system. The data acquisition system is carried out on computers and servers at AGH Krakow with the building No. 7 PNT remote data communication via the Internet network. To present the collected data, visualization has been developed, allows to display 5-minute and hourly measurements from each meter of any moment of time. The visualization includes meters installed in both the main switchboard as well as floor cabinets on the ground, first and second floors. The window of visualisation display meters for the main switchboard is shown in Figure No. 1. 1) It shows the structure of the monitoring system with 5-minute power indicators for each meter for preset time/moment. The visualization allows to observe and analyse the data form any time, with the possibility of moving about five minutes or one hour [3,23].
Fig. 1 – View of the monitoring visualization with energy meters in main switchboard
The metering system have been built using energy meters of different companies. Some types of the meters, such as U1389, allow direct data collection through a bus with international standard of building automation system – ISO/IEC 14908 (LonWorks®) [4]. Others, having only a pulse outputs, are connected to the LonWorks building automation system by appropriate modules, used to convert pulses to LON standard network variables (SNVTs). With the developed visualization system is also possible preview of all recorded parameters for each meters [3] 1). In Figures No 2a and No 2b two views of parameters form different kind of meters are presented.
Fig. 2a i 2b – An example views of the details form energy meters
Experience with implementation of the remote metering system in these buildings point to that the network building automation systems could be successfully used as a tool for organization and implementation of the Smart Metering systems, particularly in perspective of integration them with the BAS or EMS systems on the field-level. Therefore, if in buildings is infrastructure of the building automation systems, always should be considered use it to carry out mentioned tasks and functions. A very important features of the bus, international building automation systems (LonWorks, KNX, BACnet) are openness and distribution, simplify integration of the measurement and control monitoring infrastructures in one building management system BMS [24,37]. By this system it is possible to check on information from different meters and correlate it with optimal control scenarios and algorithms. It could be use also to identify areas with the greatest potential of energy save and improve energy efficiency of whole building.
It is worth noting that the mentioned Smart Metering systems have not been implemented with data collection protocol in accordance with IEC 62056 (successor to IEC 61107), dedicated to smart metering applications [30]. The measuring system have been performed using a network compliant ISO/IEC 14908, mainly used for building automation systems and in industrial automation, with option of standardized data transfer over the Internet. Use of the ISO/IEC 14908 standard infrastructure instead the IEC 62056, contributed to an easier and faster implementation and avoid the additional costs of metering and control systems installation. Recording and reporting of data was carried out using the public, free software tools, with development of own methods for processing the data. As a result, the installation allows for implementation of the Smart Metering functions:
• Identification of the distribution of energy consumption per day for all the buildings and the selected areas (floors, rooms) • Presentation of the energy consumption in different forms: graphs, trends and reports • Identify the areas with the greatest energy consumption of electricity, etc.
The system allows use of its architecture and structure to almost directly implement for monitoring and reporting of other, new buildings.
Another example of use the building automation systems as a tool to support the active energy consumers – mainly buildings’ users, is organizing of an energy management system in the buildings – EMS. This kind pilot system is implemented and researched in Certified Laboratories Network for Energy Efficiency and Building Automation – AutBudNet in AGH Krakow, equipped with infrastructure of the building automation system and BMS, based on the European and international standard ISO/IEC 14908 (LonWorks) for distributed control system [4,18,21,29,31]. With this infrastructure, it is possible to implement classical building automation functions such as lighting and heating control, access control, and more. Additionally, the automation system can operate on the field level and the remote monitoring and management of different sub-systems: fire extinguishing system, CCTV, remote meter reading of electricity consumption and heat, monitor the operating parameters of the solar collectors and PV panels. It allows use laboratory rooms as real object for research of functionalities and features of building automation systems and their influence on operation of the buildings [21,37].
In the current design practice for the building automation systems commonly used solution is implementation of different building infrastructure subsystems as autonomic installations and their integration is not possible at field level, but only at higher levels of the building management systems organization. In addition, most energy and media monitoring systems are carried out completely independent of the building automation (the intelligent control of building resources), commonly only for accounting purposes, for the suppliers of energy and media as well as costumers. It generates limitations in functionality and possibilities to devices, sub-systems cooperation. The open building automation system implemented in the AutBudNet laboratories allows integrating devices on the lowest, field level and data exchange is faster, more effective, without higher levels of monitoring and management systems. Research conducted in the AutBudNet laboratories confirm the thesis that implementation of new, distributed control systems, based on international standards, provide reduction of energy consumption in buildings by integration all automation features and functionalities and cooperation different devices and sub-systems [10]1). In the latest research several scenarios have been prepared for optimization of energy costs, depend different energy prices at different periods of days [8]. Monitoring of the control system in these scenarios as well as observation and analysis of the effects of optimization, required to organize the installation and integration of the existing energy consumption monitoring system (Smart Metering) and the energy management system (EMS). The last one cooperate with touch panels LVis by Loytec with graphical interface for user and TCP/IP and LonWorks standard interfaces for communication. Thanks this LVis panels could be connect to the BAS network directly on the field level (for example direct data exchange with meters) and remote controlled – TCP/IP communication with PCs, tablets or smartphones. For LVis panels suitable control screens have been prepared to present data from different devices and subsystems. They are presented on the 3 and 4 figures.
Fig. 3 – The LVis panel screens with selected functions and parameters from EMS.
Based on the presented system for monitoring electricity consumption with integrated subsystems of the building infrastructure, currently are conducted research aimed at long-term measuring the level of consumption in particular electrical equipment groups in the building laboratory infrastructure and their analysis1). Research workers try different new settings and correct earlier applied settings to obtain optimal work conditions – maintain comfort in rooms with a maximum reduction of energy consumption. In addition, there are verified opportunities for EMS system cooperation with different elements of HAN network – remote PCs and mobile devices, designed to support user (presentation of data, access to interim analyses, reports, energy consumption, etc.) [3,12,15,16,18]. An integral part of these networks is object-oriented communication standard LonWorks – dedicated to the building automation and increasingly used in public and commercial buildings (offices, sports and entertainment centres, etc.).
Conclusions
From the first experience, building automation systems could become an integral part of communication infrastructure organization for the Smart Metering systems in buildings. Particularly noteworthy is the ability to integrate measurement systems with building automation components in the field level. This is very important especially in larger buildings, commercial and public, where usually network infrastructure for automation and monitoring have been installed. With the mentioned integration, this infrastructure could be used for organization of the local Smart Metering systems. The user has ability to monitor energy and media consumption in building, with possibility to dynamic impact on the building infrastructure facilities integrated in the single system EMS, allowing to optimize the energy and media consumption. In addition, advanced routers and servers, dedicated to building automation, also allow remote operation with monitoring and control systems, providing user with free access to measurement data and to make the necessary changes, settings, etc.
Therefore, it is worth remembering the building automation standards in determining guidelines and standards for communication protocols, dedicated to the Smart Metering systems, especially for commercial and public buildings as well as dwellings. They allow for much easier integration of measurement systems with the overall power management system (EMS) and the whole building management systems (BMS). In perspective introduction of dynamic and interactive energy management systems (Demand Response), integration with the building automation infrastructure will enable to realize automated response procedures for all subsystems and equipment in buildings. Impulses that trigger these reactions would be outside signals – from the Measurement Information Operator, supplier of energy/media or the settings made by the user directly in the system by HAN or BMS. Importantly, part of these activities will be done automatically, without user involvement, but only with signalling events and changes in the visualization panels or dedicated websites [12,16].
In the coming years in the AutBudNet laboratories and other AGH-UST buildings, will be conducted further research on implementation of the building automation systems in the area of optimizing energy and other media consumption in the buildings and testing of various components of the Smart Metering for different types of the buildings. The results of these research and case studies, carried out on real objects with the modern infrastructure and devices integrated on the field level with international building automation standards, are quite significant. This is confirmed by strenuous activities of the U.S. and European organizations responsible for development and protection of these standards. They are engaging in any initiative on development of the Smart Metering and Smart Grid systems. Firms associated with these organizations the dominant product group are solutions and technologies to support implementation of the Smart Metering and Smart Grid, and allowing them to integrate with building automation systems. It seems, that in the coming years, this kind of application of the international standards for distributed and building automation will dominate in the field of the building automation and functionality of the EMS, BMS systems development.
1)Prace prowadzone w ramach zadania badawczego nr 5 Narodowego Centrum Badań i Rozwoju: „Zoptymalizowanie zużycia energii elektrycznej w budynkach”, w strategicznym projekcie badawczym: pt. „Zintegrowany system zmniejszenia eksploatacyjnej energochłonności budynków”.
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Authors: Marian Noga Prof. EngD., AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, al. Mickiewicza 30 build. B-1 room 120, 30-059 Krakow, E-mail: m.noga@cyf-kr.edu.pl; Andrzej Ożadowicz EngD., AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, al. Mickiewicza 30 build. C-1 room 510, 30-059 Krakow, E-mail: ozadow@agh.edu.pl; Jakub Grela MSc., AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, al. Mickiewicza 30 build. C-1 room 510, 30-059 Krakow, E-mail: jgrela@agh.edu.pl; Grzegorz Hayduk EngD., AGH University of Science and Technology, Faculty of Electrical Engineering, Automatics, Computer Science and Electronics, al. Mickiewicza 30 build. B-5 room 208, 30-059 Krakow, E-mail: hayduk@agh.edu.pl;
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 89 NR 6/2013
Published by Peter JANIGA, Dionýz GAŠPAROVSKÝ, Slovak University of Technology in Bratislava
Abstract. The aim of this paper is to share the results of measurements in public lighting networks of current status in terms of electrical characteristics. Based on the measurements it is possible to create an image of the actual power proportions in public lighting networks and the problems that arise after incorrect design. The optimal solution to the energy aspects of public lighting networks requires an assessment of a several technical and electrical inputs.
Streszczenie. Celem artykułu jest przedstawienie wyników pomiarów parametrów elektrycznych publicznej sieci oświetleniowej. Na podstawie pomiarów możliwe było odwzorowanie rzeczywistych poziomów mocy w publicznej sieci oświetleniowej i problemów pojawiających się przy niewłaściwym projektowaniu. Optymalne rozwiązanie aspektów energetycznych publicznej sieci oświetleniowej wymaga oceny kilku parametrów technicznych i elektrycznych (Pomiary parametrów mocowych w publicznej sieci oświetleniowej).
Keywords: public lighting networks, power quality, power measuring, smart metering Słowa kluczowe: publiczna sieć oświetleniowa, jakość mocy, pomiar mocy, inteligentne pomiary
Introduction
Nowadays, the energy consumption is assessed and evaluated in most of new products. In order to use technology more effectively and reduce CO2 emissions in the construction industry, new and renovated buildings are certifying since 2008. Preparation methods and determining the limits of different classes, depending on conditions in individual countries, lasted several years. The aim is to fulfil the obligations of the Kyoto Protocol, which EU committed.
Short time ago, the EU has created mandate to assess the energy consumption of public lighting systems. It is one of the best ways to evaluate the effectiveness of proposed solutions and to meet Kyoto Protocol commitments. The evaluation methodology was created in the working group CEN TC 169/226 JWG. The aim is not only define the evaluation process but also to verify the measurement of energy consumption in the sections under consideration.
Energy performance assessment methodology currently created is based on the determination of the consumption in selected sections with the same lighting parameters and geometry of communication. This method is showed in Figure 1. By comparing the calculated values and the measured values of electricity consumption are emerging differences. In order to identify and quantify these differences, the measurements in real public lighting networks was performed. From measurements is possible to identify and quantify a more conclusions. Evaluating the energy consumption in public lighting networks brings some specific problems. It is because of the harmonic currents flowing through lamps, voltage drop, load asymmetry, variability installed lamps and other factors.
Measurement of electrical parameters in public lighting networks
Lamp is a major appliance in public lighting networks. The true consumption to get in lighting networks is not possible by simply multiplying the installed power and the time of its operation. For better understanding the particularity of public lighting networks, the electrical parameters were measured in switchboards and endpoints of line.
Fig.1. Analyser connected to the switchboard
In this paper are presented the results from measuring in Slovak Republic networks. Public lighting networks have various years of construction; some networks are also reconstructed or newly built. A totally was analysed 130 public lighting networks.
Table 1. The parameters of networks
Municipality
Number of measured switchboards
Network
Michalovce
82
Cable, overhead lines
Dunajská Streda
43
Cable, overhead lines
Gabčíkovo
1
Overhead lines
Handlová
2
Cable
Galanta
1
Cable
Matúškovo
1
Cable
.
Measurements have been realised at the time of the minimum and maximum load of distribution networks in terms of distribution network impact to the public lighting network. Electricity consumption affects the size and distorted supply voltage of the surrounding customers.
Specifics of public lighting networks in determining the energy consumption
Exact determination of network power consumption in time is nearly impossible. This is due to many influences and variable network characteristics. Lamps and network analysis identified the following impacts on instantaneous consumption:
– Voltage drop, – The impact of switchboard, line, connectors, fuse and luminaries, – Power variability of lamp during stabilisation, – Passive consumption of the network, – Control, measurement, and communication equipment consumption, – Effect of harmonic voltages and currents – distortion power, – Installed regulators, – Variable operating time during the year, – Reactive power, – Load asymmetry, – Connected other devices (kiosk lighting, building illumination, etc.)
Measured data
The aim of the measurements is to determine the consumption of public lighting networks and analyse the effects to power consumption. From the measurements is possible to identify specifics of public lighting networks in terms of electrical parameters.
Effective values and transients of voltages and currents have been measured. Values have been recorded at start, during, and after stabilisation of lamp. Measuring sensors have been connected in the switchboard and in selected line endpoints. From waveforms is possible to determine voltage and current harmonic analysis at start and after stabilization.
Fig.2 Measured voltage and current (Examples – Dunajska Streda, switchboard 40, branch 1)
Fig.3 Measured active power and reactive power (Examples – Dunajska Streda, switchboard 40, branch 1)
Drop voltage
Design of cables in public lighting networks requires checking the current capacity and dropping voltage, especially if lighting regulator is used. This could be caused by reduced voltage by regulator and large voltage drops at the end of the line. Large voltage drops cause problem with discharge stability in the lamp. This problem occurs mainly for lamps with magnetic ballasts. Electronic ballasts can solve problem with voltage drop.
From measurements performed in Matúškovo it can be seen that at the end of the line voltage was out of the boundaries of EN 50 160. Although at the beginning of the branch is almost nominal voltage. This situation occurs when at the beginning of the line is almost nominal voltage. This network has been just before reconstruction and almost half of the lights have been broken. Some lamps have been connected to another phase, but it is expected that already during the construction of the network with a 250 W mercury lamps.
More often lamp switching due to unstable discharge is reason of low voltage in lighting network. This could cause the state where the two phases are interrupted.
Fig.4 Measured voltage in switchboard (green) and at the end of line (red). Measuring in Matuskovo
Variation of lamp power during stabilization
In street lighting networks, usually discharge lamps are used. For these lamps are characteristic progressive stabilisations of parameters. Stabilization of the discharge and electrical parameters is not longer than 15 minutes.
Fig.5 Current variation during stabilisation of lamp in public lighting network (inductive ballasts)
Fig.6 Current variation during stabilisation of lamp in public lighting network (electronic ballasts)
What concerns the lamp power; there are two typical situations during start-up of discharge lamps. If the lamp is supplied by inductive ballast, then current flowing in lamp is higher at start up and during stabilisation the current flow decreases. In the case of a lamp with electronic ballast, the situation is reversed. This means that due stabilisation the current increases.
Control, measurement and communication equipment consumption
The calculations consider only lines resistance. Reactance is ignored because it is several times lower. Measurement in real networks with nine lamps has confirmed a little impact on the course of the current reactance. The following figure shows, that the harmonic content is not changed by distance, but only due to distorted voltages. Slight differences are due to age of lamps (lifetime lamps are changing the electrical parameters) and small variations of electrical parts (the same lighting parameters are slightly different).
Fig.7 Effect of cable length on the harmonic content (L – light position)
Passive consumption of the network
Consumption in network consists of the consumption of lamp and consumption of the other equipments. Usually these elements are placed inside the switchboard. Passive consumption and the consumption of auxiliary equipments can be divided into two groups:
– Consumption depends on the installed power consumption, – Consumption is independent of the installed power consumption.
Passive consumption in public lighting networks is caused by loss of breakers, power control circuit (timer or sensor light intensity). This group includes the consumption of the controller.
Effect of harmonic voltages and currents – distortion power
Lamps with inductive ballast currently dominate in the public lighting networks. These lamps have a nonlinear VA characteristic and non-harmonic currents flow thru. Current distortion increases with voltage distortion. Undistorted power supply voltage does not occur.
Fig.8 Sample of the current flowing in public lighting network
Distorted currents cause distortion power. Apparent power takes into account distortion power necessary.
.
where: S– apparent power, P – active power, Q – reactive power, D – distortion power.
Finally distorted currents cause increase losses, voltage distortion and greater stress of network elements. Deformed currents flows are eliminated in lamps with electronic ballasts. Harmonic generation in the LED lamps is depending on the power supply. If the power supplies to the LED don’t have the harmonics filter such lamp generate strong distorted currents.
Installed regulators
In order to reduce the consumption of network, regulators control the power lights. Technically, regulation is designing individually in lamps or in the central switchboard. Deeper analyses are showing that the change in voltage changes the power factor and harmonic content of current. These changes are caused by changing the discharge and capacitor in lamp. In the case of voltage regulation on lamps with electronic ballasts, is to some extent this regulation is ineffective.
Fig.9 Voltage and current regulation
Some newer regulators do not change only the amplitude but also the supply voltage waveform. In such cases, it is strongly influenced by the current flow deformation in lamps.
Reactive power
Results of measurements show problem with apparent power and power factor. Although the lights have compensating capacitor, the measured values are outside the range of the desired value given by distribution network operators (PF in the range 0.95 to 1.00). Because it is a small consumption, there is no reactive consumption fee in Slovak Republic. In the measured networks losses caused by reactive power transfer are negligible. With an average wattage of public lighting network to 10 kW are losses not great. Losses due to the transfer of reactive power are not the same throughout the network. Maximum losses are near the switchboard and at the ends of line are minimal. With careful optimization of the network it makes sense to deal with this problem and eliminate possible causes.
Fig.10 Alteration power factor during voltage variation
As shown in Figure 10, there is no power factor dependence on voltage change. The problem with reactive power can occur due to loss of capacity of the compensation capacitor. This failure occurs very rarely. Another possible reason may be the usage of an inappropriate capacitor as in lamps in Galanta, where the resultant value of the power factor is 0.77 and the incremental value of the power factor of individual lights is low.
Load asymmetry
From several measurements carried out in the elderly and reconstructed networks is indicated that the load unbalance is a common phenomenon. In terms of power quality this is not a danger. It doesn’t even increase operating costs, because the distribution system operators don’t charge the load unbalance to customers.
Load asymmetry in new networks caused by the inappropriate connecting of lamps to different phases. Except the problem with uneven lighting pronounced in case of failure of one phase may be a problem with overloading phase, because the design is considered with uniform distribution. Very significantly, this problem is seen from measurements in Galanta, where all the lights are connected to one phase even if the network was made the new three-phase cable. If the new networks are not connected with balanced load, it may lead to switch off fuse of line.
Conclusion
In determining consumption in public lighting networks, it is important to first determine whether the assessed instantaneous consumption or annual. Solving instantaneous consumption is easier to take into account, however, setting the operating time. When comparing values calculated with the measured then differences may exist due to other influences such as:
– connecting other devices (phone box lighting, buildings illumination, fountains power source) – connecting a special occasional light (Christmas decoration, lighting used during holiday)
Because the measurements obtained during the large amount of data, the results are still analyse readings. For solve power balance network of public lighting with LED lighting are not some of the problems. Also in these luminaires can be clearly defined behaviour when a certain voltage. In this case, you can build a network model and make a calculation take into account the most impact.
.
This work was done during implementation of the project Effective control of production and consumption of energy from renewable resources, ITMS code 26240220028, supported by the Research and Development Operational Program funded by the ERDF.
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Authors: Ing. Peter Janiga, PhD., Slovak University of Technology in Bratislava, Institute of Power and Applied Electrical Engineering, Ilkovicova 3, 812 19 Bratislava, E-mail: peter.janiga@stuba.sk; Doc Ing. Dionýz Gašparovský, PhD., Slovak University of Technology in Bratislava, Institute of Power and Applied Electrical Engineering, Ilkovicova 3, 812 19 Bratislava, E-mail: dionyz.gasparovsky@stuba.sk
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 89 NR 6/2013
Published by B. Mary Havilah Haque1, 2. D. Jackuline Moni2, 3. D. Gracia3 1,2Karunya Institute of Technology and Sciences, Coimbatore, Tamilnadu, India 3Sri Ramakrishna Engineering College, Coimbatore, Tamilnadu, India ORCID. 1. 0000-0002-9077-7395, 2. 0000-0001-7314-023X, 3. 0002-4550-1445
Abstract. Internet of Things can ensure easy and comfortable life of the human. This present era is mostly digitized and appliances can be operated remotely by human, calling these as smart devices, smart home, smart city etc. This paper is the literature review covering the IoT applications in various fields, sectors such as smart cities and homes, health center, railway system, air pollution in environment, power/energy sector, agriculture, water monitoring for aquaculture, Space-IoT and specifies the advancements in those areas.
Streszczenie. Internet Rzeczy może zapewnić człowiekowi łatwe i wygodne życie. Ta obecna era jest w większości zdigitalizowana, a urządzenia mogą być obsługiwane zdalnie przez człowieka, nazywając je inteligentnymi urządzeniami, inteligentnym domem, inteligentnym miastem itp. Niniejszy artykuł jest przeglądem literatury obejmującej zastosowania IoT w różnych dziedzinach, sektorach, takich jak inteligentne miasta i domy, ośrodek zdrowia, sieć kolejowa, zanieczyszczenie powietrza w środowisku, energetyka/energetyka, rolnictwo, monitoring wód dla akwakultury, Space-IoT i określa postęp w tych obszarach. (Przegląd literatury dotyczący zastosowań Internetu rzeczy)
Keywords: Internet of Things, Raspberry Pi, Arduino, Monitoring. Słowa kluczowe: IoT – Internet Rzeczy.
Introduction
Internet of Things (IoT) is a system of things that are connected to one another and can collect, transfer data over a wireless network without involvement of human. If an object could be connected to the internet and is controlled and information is communicated, then the object can be an IoT device.
In 1999, Kevin Ashton made up the phrase ‘Internet of Things’. The communication among electronic devices and sensors through internet is provided by Internet of things. IoT is a solution to many of the problems faced by human. The transformation is observed in our daily routine as the involvement of IoT devices and technology is increased.
The concept of Smart Home Systems (SHS) and appliances that consist of internet based devices, automation system for homes and reliable energy management system is of the development of IoT [1]. As in [2],wireless sensor networks and IoT go hand in hand, as many fields for development of IoT technology included the application of WSN.
The IoT technology is adopted in most of the applications such as air pollution monitoring, health care, water monitoring, smart city, railway, power, agriculture, space-IoT and many other sectors. This is depicted in figure below as Fig.1.
Fig.1. Applications of IoT
In the next section, the literature review on various applications based on IoT technology is provided.
Literature Review
The literature review of the IoT based applications research work carried by different authors in various aspects is done in this paper. This paper would be helpful for all researchers as most of the IoT applications are generalized and briefed in this review paper.
Air Pollution Control
The air pollution in the environment has to be controlled in the busy areas as in the high traffic roads, industrial and machinery work fields etc. Here, the following are applications of IoT with air pollution monitoring systems.
The authors in [3] have integrated Single Board Computers (SBC) which is a Raspberry Pi with Wireless Sensor Network (WSN) for Air Pollution Monitoring (AQMS) Systems. The Raspberry pi is a fast processor and the authors have interfaced ThingSpeak web application with SBC for data monitoring. A mobile App called IoT-Mobair was developed for predicting the pollution level in the air and control it by the users or clients and the microcontroller used here [4] is Arduino. Authors in [5] used Zigbee based monitoring system of air with WSN in mesh topology using 8051 controller. A Node MCU interfaced with sensors and connected to WLAN is used in [6] for air pollution monitoring and ThingSpeak is web application. This work might be used for shorter range purpose. Using grove pi+ board and raspberry pi, the authors [7] have developed an approach for air and noise pollution monitoring in air, so that, the users are alerted with push message on their mobiles.
An interesting air pollution monitoring work was conducted in the paper [8] which is a part of GreenIoT project where the sensors installed on movable bus [9] and also stationary sensors placed in the city centre. The author [10] discusses about environment monitoring WSN model and this flow mentioned in the paper could be used for most of the other applications based on IoT. Having information and communication technology, the city officials interact with people and the problems can be solved immediately as the system of smart environment monitoring is evolved with the advancement in IoT [11]. The Arduino, NodeMCU are used in real time monitoring of pollution in the air [12, 13, 14] and vehicle user is alerted to drive through another way [15]. The popular PIC microcontroller using RISC program is included in [16].The Arduino is used in [17], GSM module is used for communication for alerting purpose [18][19]. The Raspberrry pi 3B and Arduino are used to monitor vehicle pollution in [20] and in [21], RFID for detection and Wi-Fi module is used to alert.
Smart Cities
The authors in [1], clearly say that Smart Home Systems (SHS) should have machine Learning and language processing technologies to be included to help the users in saving energy consumption, security, safety etc. Smart home with IoT application is also considered by the authors [22] where the entire house operations could be carried out though a computer and the authors also convinced us that the system should have a proper security to avoid intrusion, etc. The forest fires also have a huge impact on the city development. Detecting the forest fires by the authorities from the city in a smart way is necessary. The earlier technologies consume huge power however, in the paper [23], LoraWAN is used as it is a low power consuming protocol. And the status of sensors is known through the use of web map system. Till date we are using 4G technology but the urban and developed areas have already included 5G technology for their day-to-day applications. The authors [24] have concluded that 4G specifications are not sufficient for the demands of smart city applications and therefore the use of 5G wireless system is beneficial.
In 5G, HetNets network is used. Security is more in 5G but however this issue is always vulnerable. The adaptive admission control method is introduced by the author in [25], to enhance the response time of the IoT traffic for home WIFI IoT system and NS3 simulator is used for observation. The wireless channel impairments are nullified or suppressed. A review paper [26] on 5G technology, also deals with the same issues similar to those mentioned in the previous paper and concludes that artificial intelligence(AI), machine and deep learning must be included for 5G standardization. The rough set technique(RST) in IoT hardware is introduced in [27] to reduce the computations that are carried out during processing data. Indoor environment classification , a machine learning approach for indoor tracking and positioning which is sensor based is developed in[28] resulting in improved performance.
In solid waste management, the bin level monitoring systems including RFID and WSN are widely used and these systems are reviewed in [29]. The issues with RFID are overcome and the author has introduced system based on LoRaWAN [30]. Over the existing systems for monitoring, the authors have proposed a bin level monitoring system which is cost effective and doesn’t need additional infrastructure. In [31], an IoT based system that monitors level of bin is developed, in which the BLM unit has life expectancy of 434 days and is also cost effective when compared to other existing BLM systems. The big data [32] from water waste management, traffic and waste disposal management, resource management faces issues like data privacy, processing and quality of data, data reliability [33] is important on all of the applications like smart parking, home, traffic of vehicles, surveillance etc. The Arduino board is used in applications of dustbin cleaning, leakage of gas, detection of accident [34] and for some of the other applications RFID[35] is used for detection. The paper [36] described network protocols used in appropriate applications.
Health Care
Taking care of human health is very essential even in a busy lifestyle. With the advancement of several technologies in this era, the health care equipment’s, units, devices, etc. are also adapted to the new technologies introduced in medical field. Here, the following are applications of IoT with health care system.
The author in [37] has proposed a design for tracking the health of scavengers and used the Arduino Atmega328 as the main board and the data is sent to cloud for storage. The author in [38] has done intense research in health care sector based on IoT and has concluded that the users are beneficial with the advancement of health units working with IoT technology but the security issues alone have to be addressed as it is a challenge. As the security measure is to be dealt, the authors [39] have come up with management model for security risk in IoT to practice securely in Healthcare environment and discussed about COBIT5 for trust in healthcare unit. The WSN with IoT technology faces congestion while gathering data and can affect the reliability of the system and therefore distributed congestion control algorithm is provided in [40] whose performance is better compared to previous methods. The authors in [41] have used LS-IoT and LAC for transmission of secure data in ECG system and the signal analysis is done using SSA which considerably resulted in less energy consumption of battery.
The chronic disease patients can be remotely monitored and the various wireless networking techniques used for this purpose are discussed in the survey paper [42]. After comparing different techniques available, the authors have concluded that wi-fi technology is more advantageous for transmission of health-related data. The Arduino uno R3 with GSM module [43] is used to check blood pressure, heart rate and temperature[44]. The health check in [45] and [46] is shown using Arduino and Zigbee module. The Arduino board with wi-fi module[47] and with Node MCU in [48] is used for health check alert. The NB-IoT protocol is used as it has the advantage of low power consumption [49]. The system for covid curb to care the human society is discussed in [50].
Agriculture
Agricultural sector has to be dealt in smart way with new advancements in technology. The IoT based applications for agriculture are vast and the farmers, researchers, etc., are benefited when applied the IoT technology in agricultural field [51]. Here, the following are applications of IoT in agriculture.
The authors in [52] have combined IoT and data analytics(DA) and enabled high yield and operational efficiency. A survey paper [53] discussed all the possible advancements in agriculture and farming namely, precision agriculture, animal monitoring, tracing, greenhouse farming etc,. The cost for all this implementation is affordable by using IoT. The authors in [54] provided the survey paper and listed the strong views on the CS,ML,NOMA and mMIMO connectivity technologies for machine type communications. The temperature and humidity sensors are used for greenhouse monitoring purpose [55] and proposed the remote monitoring method combined with internet and wireless communication, and for data access ADO.NET is used. The paper[56], provides the smart system for agriculture which is a predefined irrigation schedule for improving the yield. The system includes Arduino for processing and for communication uses GSM. In [57] the sensors are connected to Arduino Uno Board for sensing soil moisture and level of water, the system of smart agriculture is designed which is automated.
The ARM7 is used in [58], in which the WSN connected in star topology. The Node MCU with ESP32 connected with sensors for monitoring crops is developed in [59]. The AVR microcontroller, raspberry pi with ZigBee module is used to control robot remotely that includes GPS [60] and the success percentage tests for routing using Raspberry pi[61] is 100%. The agro informatics is very advantageous in agriculture [62] and the precision agriculture [63] reduces the resource wastage. The sensing of soil moisture[64, 65], weather conditions [66], animal warnings through location detection by GPS [67] can help the farmers for high yield of crop. The ATMEGA328P the advanced version is used in [68] and the paper [69] collected data from 2016 to 2019 revealed that farms connected to Internet of Things are about 540 million. The solar powered system using ATMEGA2560 is introduced in[70].
Space-IoT
The satellites are used in many fields as the humans are largely benefitted. Here, the following are some of the applications of satellites in IoT.
The advantages of using satellite IoT (SIoT) networks are reliability, large coverage, security, cost effective multicasting and NB-IoT is used to sustain SIoT [71]. The SIoT is analysed in [72] for spectral efficiency improvement. Earlier GEO stationary satellites were used and even today these GEO satellites are used in some of the applications, but the authors in [73] listed out the advantages of using LEO satellites compared to GEO stationary satellites. The Arduino Uno, GSM module, GPS receiver are used to track the vehicle location [74] and developed a system of antitheft. NB-IoT is energy efficient for SIoT [75] used in long term applications. The IoT applications and its challenges are discussed in [76]. The space information network is helpful in machine communication and authors in [77] discussed that CoAP is good compared to MQTT. Landsat 8 and Moderate resolution imaging spectroradiometer [78] is used to estimate land surface temperature and evapotranspiration.
Railway Systems
The Indian government highly depends on railway sector for the income. The IoT technology advancements in railway systems makes the system run smoothly and any faults can be predicted ahead and can be prevented and made good. Here, the following are applications of IoT in Railway systems.
The train when entering a tunnel causes sickness or ringing sound in ears for few people and this happens because of the change in the pressure of air in train. To overcome this issue , the authors [79] have come up with an algorithm named adaptive iterative learning control which can balance the pressure of air. [80] deals with the idea of smart railway system (SRS). SRS requires data transaction through internet, data storage, processing etc., the network architecture IoT solution is proposed to take care of data distributed in railway area and to check performance, power consumption and concluded that LoRa as IoT network is advantageous in terms of power consumption. The TCAS is controlled with WSN [81] for maintaining train integrity. The authors in [82] provided a network architecture passenger flow distribution model for managing the passenger traffic on train and increases the traffic safety. The authors [83] introduced an adaptive fuzzy controller to adjust airgap and improved apriori algorithm is used for trusted database. Results shown with fuzzy control proposed work is very effective.
Power Sector
Enormous benefits also driven when IoT technology is used in Power systems and it may be termed as intelligent power sectors or smart power /energy systems or digitized energy system, etc. Here, the following are some of the applications of IoT based on power sectors.
The paper [84] deduced that electric power and energy systems are developed using IoT technology and helpful for Distributed Energy Resources by making less energy consumption, expense reduction and more security. The power consumption monitoring system [85] based on IoT is used and power consumption is controlled by supply cut when the limit is crossed. Here, ATMEGA microcontroller is used for processing, and the whole concept is based on ohms law. Energy management system at home based on IoT is designed in [86] where a current sensor in the form of printed circuit board is connected to all appliances and different loads of power is noted by users. The authors in [87] have reviewed literatures on energy and power sector advancements and have summarized that Variable Renewable Energy resource systems are changed to smart, digitized systems through IoT and the home can be managed by monitoring heat, ventilation, air conditioning. Blockchain technology is highlighted. The power theft and power cut manually is avoided based on the proposed work in [88]. PIC microcontroller and NodeMCU are main units. GSM module is used for alert message and RFID tag for prepaid bill payment to avoid due date issues.
Water Monitoring
The water, the main living for fish. The water parameters need to be in control as in suitable for the fish. The quality of water has to be checked in order to have a healthy fish. The following are some of the literature papers related to water monitoring.
Table 1. Types of sensors used in different application sectors
Sensors
Application sector
GP2Y1010AU dust sensor MH-Z14 CO2 sensor DHT sensor MQ series gas sensor DSM501A dust sensor PMS3003 G3 particle sensor MICS-4514 sensor
Air Pollution
BP sensor MAX30205 digital thermometer ECG/EKG sensor Pulse sensor Biosensors, Physical sensors pH sensor-WQ201 Pressure/Strain sensor Temperature sensor-WQ101 dissolved oxygen sensor-WQ401 Audio microphones, MLX90632 sensor
In [89], the quality of water monitoring for Eel fish using Raspberry pi 3 is done. Here, the dissolved oxygen is little less than the actual needed by the fish. An aquaculture with high density [90] using Raspberry pi is done, in which, the temperature from many tanks can be sensed at the same time. The Arduino is used in[91] and notification alert on phone can be received in the system [92]. The effective system [93], in which, the self-cleaning sensor probes are equipped. The review on WI-FI, GSM and Zigbee based monitoring systems are discussed in [94]. An Approach using NB-IoT is done in [95]. Having 6LoWPAN [96], monitoring of water is done and system enhances the work of old traditional monitoring of water. The parameters like pH, dissolved oxygen, water temperature were discussed in [97] [98] and in [99] it is advised not to use a black tarpaulin as pond for fish as it is not a good option.
Inference from the above papers drawn is, the sensor networks that are ZigBee based is recommended and for the quality of water monitoring with self-cleaning probes is a good option for effective reading of values of results.
Based on the study of the papers reviewed, the conclusion made is listed in tables 1 and 2. The main board either Raspberry pi, Arduino or NodeMCU for any application, can be used based on the priorities of the researcher.
Table 2. Difference between Raspberry Pi, Arduino and NodeMCU
Parameter
Raspberry Pi
Arduino
NodeMCU
Clock speed
1GHz
16MHz
80-160MHz
Type
Small computer
Microcontroller board
Microcontroller board
Operating voltage
5V
5V
3.3V
Board with both Wi-Fi and Bluetooth built-in
Yes
No
Yes
.
The figure (see Fig.2.) shows the power consumed by NodeMCU, different Raspberry Pi and Arduino models. The main difference between Raspberry Pi and Arduino is that, Arduino and its models are microcontroller development boards, whereas, the Raspberry pi and its models are like mini computers that needs operating system and therefore, Raspberry pi requires more power compared to Arduino. The speed of Raspberry Pi is faster than Arduino. The Arduino cost is cheaper. Hence, researcher according to the parameters required for the particular project can choose the specific board.
Fig.2. Power consumption
Conclusion
The wireless sensor network (WSN) is the sensor network that has to be connected to processor for processing the data and this data is accessed by the receiver on the user side. Therefore, all the devices have to be connected through internet and the devices may sometimes be performed remotely and independently. IoT is very apt to be used in this field of work. Internet of Things (IoT) technology is very useful and highly advantageous to be used in the work of sensing and monitoring. The human living to some extent can be eased with the use of the advanced technology. This review paper is helpful for all the researchers of IoT topic.
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Authors: B. Mary Havilah Haque, Research Scholar, Electronics and Communication Engineering Department, Karunya University, Coimbatore, Tamil Nadu, India, E-mail: havilah737@gmail.com;prof. Dr D. Jackuline Moni, Professor, ECE Department, Karunya University, Coimbatore, Tamil Nadu, India, Email: moni@karunya.edu.in;Dr. D. Gracia, ECE Department, Sri Ramakrishna Engineering College, Coimbatore, Tamil Nadu, India, E-mail: graciadevaraj@gmail.com
*Corresponding Author, moni@karunya.edu
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 97 NR 12/2021. doi:10.15199/48.2021.12.08
Publishing by Paweł WĘGIEREK, Michał KONARSKI Lublin University of Technology, Faculty of Electrical Engineering and Computer Science, Lublin, Poland
Abstract. The smart metering to the power system implementation significantly changes the way of measurements and settlements in the electricity sector. This paper presents an analysis of realized measurement accuracy and the key information about the smart metering and the components of the advanced metering infrastructure. It also shows the scope of authors’ ongoing research on the temperature effect of electricity measurement accuracy in the smart metering system.
Streszczenie. Wprowadzenie do systemu elektroenergetycznego inteligentnych systemów pomiarowych znacząco zmienia sposób przeprowadzanych pomiarów i rozliczeń. W artykule przedstawiono analizę dokładności realizowanych pomiarów oraz zaprezentowano kluczowe informacje dotyczące inteligentnego systemu pomiarowego i zaawansowanej infrastruktury pomiarowej. Przedstawiono również zakres aktualnie prowadzonych przez autorów niniejszego artykułu prac badawczych, dotyczących wpływu temperatury na dokładność pomiarów energii elektrycznej w inteligentnych systemach pomiarowych. (Dokładność pomiarów energii elektrycznej w inteligentnych systemach pomiarowych).
Keywords: electricity measurement, measurement accuracy, smart metering, smart grid. Słowa kluczowe: pomiary energii elektrycznej, dokładność pomiarów, inteligentne systemy pomiarowe, sieć inteligentna
Introduction
The smart grid implementation in Poland recently definitely accelerated. Successful pilot programs resulted in the beginning of new, large-scale investments. The smart metering system is an essential part of the smart grid. The smart grid can be described as a modernized electricity grid supplemented by a digital two-way communication system between a supplier and a consumer and smart measurement and monitoring systems [1]. The main smart grid concept is an integration of activities of all participants in the process of generation, transmission, distribution and consumption of electricity, in order to deliver it in an economical, safe and secure manner. The realization of this objective is only possible by taking multi-faceted activities. The most important actions related to the smart grid introduction are substitution of a conventional, centralized model of the electricity generation by a dispersed model and complement an energy transmission layer by an information technology layer, permitting advanced measurement and control functions [2].
Smart Metering System
The implementation of the smart grid and the achievement of its objectives are not possible without the introduction to the power system advanced metering, control and safety infrastructure [2]. A fundamental part of the intelligent infrastructure, particularly from the customer perspective, is the smart metering system, which is a common system for automatic measurements, two-way exchange of information and transmission of signals and commands to final customers [3]. The smart metering system consists of two equivalent parts – the advanced metering infrastructure and the meter data management system. The advanced metering infrastructure (AMI) is an integrated set of measurement elements, consisting of smart meters, communication modules and systems, data concentrators and recorders, which enable two-way communication between meters and the meter data management. Meter data management system (MDM) is a computer system used in measurement data processing for billing purposes and to cooperate with other information systems [4].
The most important difference between the smart and the conventional metering system is the implementation of a two-way communication between a meter and a power system operator, enabling a complete automation of the electricity settlement process [4]. Achieving the two-way communication is not possible with commonly used analog electricity meters. This effect can be accomplished only by the use an electronic, equipped with communication module meter – called a smart meter. A meter-MDM communication can be done in two ways – directly using the GSM network or indirectly through a collecting device called a data concentrator. Most of the present methods based on the solution using the concentrator. The concentrator is generally placed in a MV/LV transformer station and it is responsible for a multiple meters communication with the MDM. A meter to concentrator communication is realized by using the power line communication (PLC). Measurement data from the concentrator is then routed to the connected communication module, linking with the MDM via GSM [5]. All of these devices and communication methods are parts of the AMI, which simplified structure is shown in figure 1.
The main objective of the smart metering implementation is to rationalize electricity consumption, which shall reduce overall cost of the power system operation. Smart metering is expected to create many benefits to all participants in the process of production, distribution and consumption of the electricity. The introduction of new technology will mean [6]:
• for distribution system operators – reduction of cost by obtaining more accurate market data and revenue increase by reducing losses and inefficiencies, • for the transmission system operator – improvement of system security and reduction of the balancing mechanism cost, • for electricity sellers – ability to customize offers to the individual needs of final customers, • for electricity producers from renewable sources – facilitation in processes of settlement and grid connection, • for final customer – liquidation of based on forecasts settlement, energy saving possibility by the use of advanced monitoring tools and improvement of the electricity quality.
The smart metering is now a primary area of the Polish smart grid implementation. In addition to the benefits, significant impact on the smart metering development have applicable legal regulations, such as Directive 2009/72/EC of the European Parliament and of the Council, which requires member states the obligation to equip in smart metering systems by 2020 at least 80% of customers [7]. In the Polish case, this means the need to install by 2020 approx. 15 million smart metering systems, with the current implementation level of only 2.7% [6].
Fig.1. Advanced metering infrastructure [8]
Smart Electricity Meter
A smart electricity meter (Fig. 2.) is a basic element of the AMI and of its functionality affects the functionality of the entire metering system. The most important feature of this meter is the possibility of a two-way communication with the power system operator. The communication is implemented in the PLC technology via a built-in communication module, enabling the connection to a data concentrator. In justified cases, complement of the PLC transmission can be direct communication with the MDM via the GSM transmission
Fig.2. Smart electricity meter [9]
In the order to ensure the quality of measurement and communications, a smart meter must meets the requirements set out in the applicable, published by the Polish Energy Regulatory Office The Exemplary Technical Specification for the standard tender procedures for the supply of metering infrastructure for AMI systems. According to the Specification, smart meter must enable [5]:
• two-way active energy measurement and registration in the accuracy class at least B, • four-quadrant reactive energy measurement and registration in the accuracy class at least 3, • load profile registration in 15, 30 and 60-minute intervals, • operating temperature range at least -30°C / +70°C, • two-way PLC communication with a data concentrator, • electricity supply monitoring, • remote reading of measurement data on a concentrator demand, • immediately transmission of information about power failure, cover opening or activation of an external magnetic field, • remote change of the applicable tariff, • remote customer connection and disconnection.
Measurement Data Concentrator
A measurement data concentrator (Fig. 3.) connects customers’ meters with the MDM. The main task of the concentrator is to download via PLC measurement data from meters, and then transfer them via Ethernet, modem and GSM to the power system operator. Most of the commercially available concentrators allow the use of an external or built-in modem.
Fig.3. Measurement data concentrator [10]
Similarly to a meter, a data concentrator also must meet a number of requirements specified in The Exemplary Technical Specification. According to the Specification, data concentrator must enable [5]:
• operating temperature range at least -25°C / +60°C, • two-way PLC communication with at least 800 meters, • acquisition of measurement data from the meters at least four times a day (in the six-hour cycles), • two-way communication with the MDM via Ethernet, modem and GSM, • transmission of measurement data to the MDM at least once a day, with the exception of data requiring immediate transmission.
Power Line Communication
The primary method of communication between the meters and the concentrators in the AMI is the power line communication. This communication used as a transmission medium a low-voltage power grid and is made possible by the use of communication modules in the grid devices. The basic PLC operating principles are modulation and demodulation. The modulated high frequency signal is added to the voltage waveform in the supply line. The receiving module separates the transmitting baseband signal from the supply voltage and restores the original data by demodulation [4]. The bandwidth currently used in the Polish grid is the CENELEC A band of frequencies 3 – 95 kHz using the Orthogonal Frequency-Division Multiplexing modulation (OFDM), which consists in dividing the frequency band into many independent carriers and transmit several data streams in parallel [5,11]. The OFDM modulation operating principles is shown in figure 4. The most important requirement for the PLC communication is assuring appropriate quality, which is affected by the grid infrastructure condition as well as interference and noise made by other devices and external factors [4, 5].
Fig.4. OFDM modulation [11]
Electricity Measurement Accuracy
The use of advanced metering infrastructure has a significant impact on the electricity measurement accuracy. In the traditional approach, the only device affecting the accuracy is a meter. The smart metering system measurement quality depends on more elements, which is associated with extended measurement data flow path from a meter to the MDM. Measurement precision in the smart metering typically depends on the quality of:
• meter measuring and registering, • PLC modulation in a meter communication module, • supply line PLC communication, • concentrator PLC/Ethernet processing, • Ethernet communication, • modem Ethernet/GSM processing, • GSM communication, • GSM/Ethernet processing of a MDM communication module.
The basic AMI element, which has the greatest impact on the measurement accuracy, is an electricity meter. Also used as a component in the traditional measurement systems, it has well defined metrological requirements. The main parameter determining the quality of the meter measurements is its accuracy class, specifying the maximum permissible error at reference conditions. These values are determined separately for active and reactive energy measuring. In smart meters the minimum class for an active energy measurement is B – corresponding to the 1% maximum permissible error. A reactive energy measurement must be realized in the accuracy class at least 3, with the 3% maximum permissible error. These requirements, as mentioned previously, apply only to the reference conditions. This means, that at changing external conditions or worse quality of the supplied power, the measuring quality may be decreased [5,12,13]. Influence quantities of the meter maximum permissible error are an ambient temperature, voltage and frequency changes, voltage unbalance, harmonics presence as well as magnetic induction and electromagnetic field effect [14]. The error introduced by the influence quantities is called the additional error and it affects the value of the maximum permissible error in other than the reference conditions. For example, the maximum permissible error of the class B meter, which is 1% in the reference conditions, in adverse conditions may rise to 4.5% and this will be a correct and class-consistent value [14]. Requirements for meters are distinctly defined in the law as well as in the Polish and the European standards. The question is whether the currently installed, yet unproven on a large scale smart meters, meet all the requirements and whether their measurement accuracy is sufficient.
In the case of other AMI components metrological requirements are not clearly defined. This applies to both physical devices and communication methods. The lack of regulations is probably associated with the relatively recent introduction of these components for measuring systems. No metrological requirements for these parts and small scale of existing implementations resulting in an unspecified accuracy of the overall measuring system. It is especially important from the perspective of the electricity settlement, where errors in the measurement data transmission and processing have a direct impact on the customers’ bills, which in the smart metering are issued automatically. These facts prove the need for urgent legal control of the smart metering measurements quality. Fortunately, this problem was already discussed in the ongoing legislative works. The draft law proposed by the Ministry of Economy assumes, that minister responsible for the economy will specify, by ministerial decree, the detailed operating conditions of the measuring system. The decree shall contain [6]:
• measuring system requirements, • requirements of: –> communication standards between a smart meter and the MDM, –> measurement data, –> commands received by the smart meter and the conditions of their transfer, • measurement data correcting methods, • communication reliability parameters.
The decree should introduce solutions to ensure the metrological control of the all smart metering components. However, the legislature provided that the proposed law will not come into force until 1st January 2016 [6].
Ongoing Work
The presented situation requires a comprehensive verification of the measurement accuracy in the smart metering system. It is especially important to check the measurement accuracy at varying operating conditions, where, in the most unfavorable cases, may occur an extreme errors. One of the most significant influence quantities seems to be the ambient temperature. This assumption is associated with the use in the smart metering system of temperature-responsive semiconductor devices and the location of most of the system components in places directly exposed to the outdoor temperature. The temperature effect of electricity measurement accuracy in the smart metering system is the subject of authors’ ongoing research.
The research scope includes an analysis of temperature effect on quality of:
• measurement and registration of the smart meter, • data processing of the smart meter communication module, • PLC transmission, • data processing of the data concentrator.
The research is carried out by using a specialized climatic chamber, which allows conducting tests in constant, user-specified temperature. The university-owned chamber is Discovery DY600C, produced by Angelantoni Industrie, with a useful capacity of 559 liters. The chamber enables conducting experiments at the temperature range from -75°C to +180°C. The use of advanced adjusting methods provides exceptional stability of internal climate conditions, with the possible temperature fluctuation of only ±0,1°C to ±0,3°C. Due to equip the chamber with the hermetic portholes it is possible to input and output electrical wiring without affecting the internal temperature stability.
Conducted experiments consist of placing inside the climatic chamber tested AMI component, verifying the obtained at a set temperature amount of electric energy consumed by a connected receiver and comparing it with the amount obtained in the reference conditions (temperature of 23°C). For each temperature, on the basis of received values, is calculated a temperature additional error. In the first stage, the research is conducted in device operating temperature range (-40°C to +70°C for the meter, its communication module and PLC communication, and -25°C to +60°C for the data concentrator). In the next research stage it is planned to expand the experiments outside the operating range. To thoroughly check the measurement system operation, the tests are conducted for different devices producers and for different types of loads – both for their power (load current from 0.25 A to 16 A) and character (power factor from 0.5ind to 0.8cap). The first device under test is the three-phase smart electricity meter with built-in GSM/GPRS modem. The meter enables measuring and registration of active (two-way, accuracy class B) and reactive (four-quadrant, accuracy class 2) energy and it allows all other activities required for the smart meter, such as load profile registration, electricity supply monitoring and remote two-way communication. It is also equipped with optical port for local meter programming and data downloading. The tested meter’s operating temperature range is -40°C to +70°C.
The main objective of the research is to determine the real effect of temperature on indicated by metering system amount of consumed electric energy. An additional objective for the meter is to check whether its accuracy is class-consistent. The expected result of the research is a significant deterioration in the accuracy with moving away from the reference temperature. In the meter case it is also expected the possibility of exceeding, in the most unfavorable temperatures, a maximum permissible error.
Conclusions
Implementation of the smart grid and the smart metering system seems to be unavoidable because of the possible benefits and applicable legal regulations. This situation significantly changes the way of measurements and settlements in the electricity sector. Universality and scale of the introduction of the advanced metering infrastructure requires the special care about its measurement quality. The appropriate measurement accuracy is particularly important from the electricity settlement perspective. Not all of the AMI system components are now covered by the legal metrological control, which can lead to abnormalities of realized measurements. Particularly important for the measuring system operation is its appropriate work also at varying operating conditions. The research conducted by the article authors aims to determine the relationship between the measurement accuracy and the ambient temperature. The results and the conclusions of this research will be presented in the future publications.
REFERENCES
[1] European Commission, Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions – Smart Grids: from innovation to deployment, Brussels, Belgium, 2011 [2] Andrzejewski M., Gacek A., Energy and data flow in traditional and smart electric power grids, Wiadomości Elektrotechniczne, vol. 1042, No. 9, 110-112, 2013 [3] Urząd Regulacji Energetyki, Stanowisko Prezesa URE w sprawie niezbędnych wymagań wobec wdrażanych przez OSD E inteligentnych systemów pomiarowo-rozliczeniowych z uwzględnieniem funkcji celu oraz proponowanych mechanizmów wsparcia przy postulowanym modelu rynku, Warszawa, Poland, 2011 [4] Billewicz K., Smart metering – Inteligentny system pomiarowy, Wydawnictwo Naukowe PWN, Warszawa, Poland, 2011 [5] Urząd Regulacji Energetyki, Wzorcowa Specyfikacja Techniczna dla postępowań przetargowych na dostawę infrastruktury licznikowej dla systemów AMI, Warszawa, Poland, 2014 [6] Minister Gospodarki, Projekt założeń do projektu ustawy o zmianie ustawy – Prawo energetyczne oraz ustawy o zasadach pokrywania kosztów powstałych u wytwórców w związku z przedterminowym rozwiązaniem umów długoterminowych sprzedaży mocy i energii elektrycznej, Warszawa, Poland, 2014 [7] European Parliament and of the Council, Directive 2009/72/EC of the European Parliament and of the Council of 13 July 2009 concerning common rules for the internal market in electricity and repealing Directive 2003/54/EC, Official Journal of the European Union, vol. L 211, 55-93, 2009 [8] Rozwałka T., Budowa infrastruktury inteligentnego pomiaru w PGE Dystrybucja SA, Proceedings of XX Forum Teleinformatyki, Miedzeszyn, Poland, 2014 [9] Apator S.A., EQUS Trójfazowy Licznik Energii Elektrycznej, Available at: http://www.apator.com/pl/oferta/pomiarenergii/liczniki-energii-elektrycznej/liczniki-smart/equs, accessed on 17 February 2015 [10] Landis+Gyr AG, Data concentrator DC450 Technical Data, Available at: http://www.landisgyr.com/webfoo/wp-content/uploads/2013/05/03.300-DC450_Technische_Daten-e.pdf, accessed on 17 February 2015 [11] Szenk M., Komunikacja PLC (OFDM) w Systemach Zdalnych Odczytów, Urządzenia dla Energetyki, vol. 56, No. 5, 46-48, 2011 [12] Minister Gospodarki, Rozporządzenie Ministra Gospodarki z dnia 4 maja 2007 r. w sprawie szczegółowych warunków funkcjonowania systemu elektroenergetycznego, Dziennik Ustaw 2007, nr 93, poz. 623, Warszawa, Poland, 2007 [13] Minister Gospodarki, Rozporządzenie Ministra Gospodarki z dnia 7 stycznia 2008 r. w sprawie wymagań, którym powinny odpowiadać liczniki energii elektrycznej czynnej prądu przemiennego, oraz szczegółowego zakresu sprawdzeń wykonywanych podczas prawnej kontroli metrologicznej tych przyrządów pomiarowych, Dziennik Ustaw 2008, nr 11, poz. 63, Warszawa, Poland, 2008 [14] Polski Komitet Normalizacyjny, PN-EN 62053:2006 – Urządzenia do pomiarów energii elektrycznej (prądu przemiennego) – Wymagania szczegółowe, 2006
Authors: dr hab. inż. Paweł Węgierek, prof. PL, mgr inż. Michał Konarski, Lublin University of Technology, Department of Electrical Devices and High Voltages Technologies, Nadbystrzycka 38A, 20-618 Lublin, Poland, E-mail: p.wegierek@pollub.pl, konarski.michal@pollub.edu.pl.
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 91 NR 12/2015. doi:10.15199/48.2015.12.04
Published by Wiesława MALSKA1, Anna KOZIOROWSKA2,3, Dariusz SOBCZYŃSKI1 Rzeszow University of Technology, The Faculty of Electrical and Computer Engineering, Department of Power Electronics and Power Engineering (1) University of Rzeszow, Department of Mathematics – Natural Sciences, Institute of Technics (2) Institute of Applied Biotechnology and Basic Science University of Rzeszow, (3)
Abstract. Specialized laboratory equipment, often uses power converters, which are the source of higher harmonics. These devices, depending on their functions, are composed of several additional elements (such as UV light, a heater).They also enable the speed adjustment .Mostly, these are low-power devices used in laboratories, scientific research units engaged in research and teaching.
Streszczenie. Specjalizowane urządzenia laboratoryjne, bardzo często wykorzystują przekształtniki energoelektroniczne, które są źródłem wyższych harmonicznych. Urządzenia te w zależności od swoich funkcji składają się z kilku dodatkowych elementów (np. lampa UV, grzałka), a także umożliwiają regulację prędkości. Najczęściej są to urządzenia małej mocy i stosowane są w laboratoriach badawczo-naukowych jednostek prowadzących badania naukowe i zajęcia dydaktyczne. (Specjalizowane wyposażenie laboratorium biotechnologicznego z uwzględnieniem wyższych harmonicznych)
Słowa kluczowe: odkształcenia napięcia i prądu, wyższe harmoniczne, specjalizowane urządzenia laboratoryjne Keywords: Voltage and Current Distortion, Higher Harmonics, specialized laboratory equipment
Introduction
Commonly used non-linear devices are the sources of higher harmonics, which increase the apparent power of devices and power losses in the power lines, but information about their impact on the supply network of specialized laboratory equipment can rarely be found in the literature. Higher harmonics also cause electromagnetic interference and sometimes strong resonance phenomena. In this way, they adversely affect the operation of security systems, automation and control systems, robot and communication, as well as other receivers of electricity. The results are economic losses caused by decrease in reliability and service life of these devices. Correct operation of electrical equipment is possible under the right conditions, in terms of the guarantee by the manufacturer of the device. They mainly concern the environment in which the device will operate, the quality of the supply line and the level of electromagnetic interference affecting the inverter. At the same time power electronic equipment should not be cumbersome to operate, and in particular it should not adversely affect the operation of other devices – in particular electrical equipment [2,3,4].
We can talk about the power quality standard, if in the place of observation (measurement) the voltage curve is exactly sinusoidal, the nominal frequency and its rms value is equal to the rated voltage. In practice, this ideal situation is not available and necessarily power quality is considered acceptable if the deviation from the standard of the quality is not adverse for the selected device (do not interfere with its operation). A growing number of different sets connected to the power system affects the intensity of the interaction between them, which in the end leads to a deterioration of their electrical conditions of operation. This interaction is mediated by mutual galvanic coupling from the supply network and the electromagnetic waves emitted by the receivers (electromagnetic interference – EMI) [5,6,7,8,9]. Converters adversely affect a supply line and are a source of electromagnetic interference. They are susceptible to interference reaching from the power supply and from electromagnetic fields generated in their main circuits, and generated by other adjacent equipment.
Electric operating conditions of power electronic devices are determined primarily by parameters of AC or DC supply line, the intensity of different types of electromagnetic interference and type of load. Hence the need to take into account the nature of the operation of specialized laboratory equipment, which is often found in the same room in a laboratory, and is supplied from the same power network. It should be noted that operating time of specialized equipment varies and depends on whether the measurement tests are done and how many instruments work at the same time. The target scientific functions are different, depending on the purpose of the study and the type of a device, but nevertheless all the devices are supplied from the same power network [10,11,12,13,14,15,16,20]. Therefore, knowledge of the characteristics of these devices is important.
The paper shows the results of measurement tests of the impact on a supply network of two devices – a laminar chamber and a thermal cycler. The structure and appropriate control of the device are important to reduce or minimize the negative effects of this type of equipment to power supply from the point of view of a power network. The research was engaged in the laboratory of the Institute of Applied Biotechnology and Basic Sciences University of Rzeszow in Werynia.
Characteristics of the laboratory equipment
The thermal cycler is an electric device which controls the temperature. The samples placed in the device are alternately heated and cooled in accordance with the requirements of the methodology used in the PCR (Polymerase Chain Reaction) e.g. to reproductive DNA chains in the laboratory conditions. PCR has many applications – for example, in the study of genes (gene cloning, characterization of gene expression), in the identification of missing persons, in establishing paternity and paleontology. The thermal cycler, which is a basic device used in molecular biology laboratories, offers fast temperature control.
Two models of thermal cycler were tested – Mastercycler Personal and Mastercycler Gradient. The state of start-up and increase of the temperature as well as a condition of stable operation of equipment were measured.
A chamber with laminar air flow is electrical equipment used in molecular biology laboratories in order to protect the sample from contamination. Through the use of biosafety cabinets sterile working area in the laboratory is obtained.
Phot.1. The measurement tests of Mastercycler Gradient thermal cycler
They are used during sterile work in microbiology and in vitro culture of plant and animal cells. They protect the environment from contamination during the work with the use of hazardous materials (eg, infectious bacteria and viruses, GMOs). The cells in the culture require providing an environment simulating the natural one. One of the factors is a sterile environment for growth. It should provide adequate temperature and humidity. The laminar chamber provides cells with the sterile environment while working with them. The air in the chamber is passed through a special filter, which provides the purification of bacterial or fungal spores which cause the infection arising [1].
The various states of a Thermo Scientific laminar chamber were studied. This is a chamber of class II safety designed to work with infectious material (tissue, blood, viruses, bacteria) and pure material requiring protection (cell culture), with a capacity of 0.8 kW. It has two filters – the main and in the air outlet. The efficiency of the filter is 99.999% for particles of 0,3μm. It has the microprocessor control which allows controlling both the flow of air in the working chamber and the use of filters. The laminar chamber is supplied from single-phase. At first the study included the start-up state – the preparation of chamber to work. Then the operating conditions when using the blower and the UV lamp were studied.
Results of laboratory tests
In order to analyze the work of selected biomedical laboratory equipment for selected indicators and power quality parameters, selected quantities were measured in the laboratory of the Centre of Applied Biotechnology and Basic Sciences, where the equipment is used for scientific research. As the measure of evaluation of harmonic distortion HD (Individual Harmonic Distortion) and Total Harmonic Distortion THD [17,18, 19] were assumed.
Total Harmonic Distortion factor THD (voltage or current) is defined as the ratio of the rms value calculated excluding the first harmonic (it is assumed that the constant is zero) to the value of the first harmonic effective:
.
where X(k) was determined as the rms value of the k-th harmonic of the signal x(t).
The contribution of each harmonic in the final shape is defined as an individual signal distortion factor HD (current or voltage) and is calculated from the formula:
.
where: X(k) – rms value of the harmonic of k order, k = 2, 3, 4, …, n; n – number of harmonic taken into account in analysis, in accordance with PN-EN 50160 n=40; X(1)– rms value of fundamental harmonic.
The paper also contains the rms value of current waveforms under varying operating conditions, to characterize the changes in power consumption.
Figures 1-2 show the waveforms of rms values of current of thermal cycler in various stages of work, from preparation to work with the heater on and off, as well as start-up to a normal, stable operation.
Fig.1. The course of thermocycler rms current value for 50 seconds, switching on and off the heater (Mastercykler Personal)
Fig.2. The course of thermocycler rms current value within 170 seconds, the preparatory work from the start to a stable job
Waveforms of rms current does not allow for an evaluation of the distortion, so in the following section there is provided the analysis of the components of distortion. Considerations concern a variety of operating conditions of biomedical laboratory devices.
The individual factor of supply current distortion of a thermocycler (Mastercykler Gradient type) shown in Figure 3 for the standby operating status, clearly shows the large distortion of the supply current, and the value of the THD of current is 75.6% (the value of the voltage THD was 1.74%)
Fig.3. Individual Harmonic Distortion of supply current of Mastercykler Gradient (standby status)
Large values of THD factor indicate high amplitudes of higher harmonics (mainly harmonic: the third, fifth, eleventh, thirteenth, etc.).
Figures 4-5 contain an individual supply current distortion factor for the thermal cycler at 58 °C (operation with heater turned on) and steady state (“Second” heat cycle (high time constant)).
Fig.4. Individual Harmonic Distortion of supply current of Mastercykler Gradient (standby status) (operation with the heater turned on – the temperature 58 °C)
Fig.5. Individual Harmonic Distortion of supply current of Mastercykler Gradient (“Second” heat cycle)
Visible differences on the graph of HD factor in fig. 4 and fig. 5 show different ways of control dependent on a thermocycler mode of operation, in particular, the setting and a way of temperature control inside the thermal cycler. THD current factor for the case of a heater turn on is 71,9% (THD of voltage is 1,88%), and for the case with second cycle of heating is 57,1%. It is related to the long duration of the temperature increase inside the thermal cycler (voltage THD 1.81%).
Figures 4-5 show high values of HD factor for individual harmonics, which demonstrate the diverse nature of the work, depending on the selected mode of operation.
For the laminar chamber, measurements for different states of work were performed – from the state of preparation to work, the inclusion of fan until the UV lamp is turned on.
Figures 6-8 show graphs of individual factor distortion HD for the laminar chamber. In Figure 6 for the standby status, current THD value in this case was 30.5% (THD for a supply voltage was 1.7%), for the case of Figure 7 THD current value was 18.9% (a value of voltage THD was 1.79%). It was the case with the fan turned on inside the laminar flow. In fig. 8 a change of HD factor value for individual harmonics is shown, for the UV lamp turn on inside the laminar chamber, and at the time of measurement value of current THD was equal to 24.8% (a value of voltage THD was 1.71%).
Fig.6. Individual Harmonic Distortion of supply current of laminar chamber (standby status)
Fig.7. Individual Harmonic Distortion of supply current of laminar chamber (operation with the fun turn on)
Fig.8. Individual Harmonic Distortion of supply current of laminar chamber (operation with the UV lamp turn on)
Figure 9 shows a course of rms current value of laminar chamber during 170 seconds of work.
The first seconds are a start-up, pumping the air out of the chamber, and in the 148 second the UV lamp was turned on.
Fig.9. The course of rms current of laminar chamber within 170 seconds, the first seconds are the cycle of preparatory work, in the 148 second, the inclusion of a UV lamp
Summary
Based on experimental studies using a Yokogawa WT 500 power meter (which allows the simultaneous measurement of voltage, current, power, and total harmonic distortion), the evaluation of harmonics generated to the power supply by two selected specialized laboratory items of equipment can be carried out.
The first analyzed device – the thermocycler – depending on the nature of the work (as start-up, the status of temperature control (switching on and off the heater) is an example of the so-called. “restless” receiver. The next analyzed device – a laminar chamber is the same type of a device (the change of current distortion is visible in changes of the operating mode (turn on or off the fan, turn on or off the UV lamp, keeping a constant temperature level. Both devices placed in laboratories of Centre of Applied Biotechnology and Basic Sciences are used every day for about 10 hours.
Therefore, they are a source of harmonics generated to the supply network. At the same time, the same network supplies highly specialized unique devices for molecular analysis, for example Real Time PCR, sequencer, spectrophotometers and chromatographs. Research related to the evaluation of specialized biomedical laboratory influence on supply network continues. The results of these studies will be presented in subsequent papers. This work aims to assess the level of current distortion generated in the whole research biotechnology laboratory and development of the manner of their limitations.
The study was performed within the project Centre of Applied Biotechnology and Basic Sciences supported by the Operational Programme Development of Eastern Poland 2007-2013, NoPOPW.01.03.00-18-018/09.
REFERENCES
[1] Kalinowska K., Ogórek R., Baran E. – Diagnostyka mikologiczna: wczoraj i dziś. Od mikroskopu do termocyklera, Mikologia Lekarska 2011, 18 (3): 156-158 [2] Barlik R., Nowak M.: Jakość energii elektrycznej – stanobecny i perspektywy. Przegląd Elektrotechniczny , nr 7-8 2005, [3] Hanzelka Z.: Rozważania o jakości energii elektrycznej. Elektroinstalator nr 9/2001- 2/2002 [4] Malska W., Łatka M.: Wpływ odbiorników nieliniowych na parametry jakości energii elektrycznej, Wiadomościi Elektrotechniczne, nr 10, 2007r. [5] Nowak M., Barlik R.: Poradnik inżyniera energoelektronika, WNT, Warszawa 1998 [6] Paice Derek A.: Power electronic converter harmonics, IEEE Press, New York 1996 [7] Piróg S.: Energoelektronika: układy o komutacji sieciowej i o komutacji twardej), Uczelniane Wydawnictwa Naukowo-Dydaktyczne, AGH, 2006 [8] Strzelecki R., Supronowicz H.: Filtracja harmonicznych w sieciach zasilających prądu przemiennego, Postępy Napędu Elektrycznego, 1998 [9] Bartman J., Koziorowska A., Kuryło K., Malska W. – Analiza rzeczywistych parametrów sygnałów elektrycznych zasilających układy napędowe pomp wodociągowych – Przegląd Elektrotechniczny, 2011/8, str. 8-11 [10] Ustawa z dnia 10 kwietnia 1997 r. Prawo energetyczne. Dz.U. nr 54, poz. 348 z późniejszymi zmianami [11] Norma PN-EN/50160 Parametry napięcia zasilającego w publicznych sieciach rozdzielczych. PKN 1998 [12] Rozporządzenie ministra gospodarki i pracy z dnia 20 grudnia 2004 r. w sprawie szczegółowych warunków przyłączenia do sieci elektroenergetycznych, ruchu i eksploatacji tych sieci. Dz.U. z 06.01.2005 [13] PN-EN 50160:2002 Parametry napięcia zasilającego w publicznych sieciach rozdzielczych. [14] PN-T-03501:1998 Kompatybilność elektromagnetyczna (EMC). Dopuszczalne poziomy. Ograniczanie wahań napięcia i migotania światła powodowanych przez odbiorniki o prądzie znamionowym większym niż 16 A, w sieciach zasilających niskiego napięcia. [15] PN-EN 61000-3-2:1997 Kompatybilność elektromagnetyczna (EMC). Dopuszczalne poziomy. Dopuszczalne poziomy emisji harmonicznych prądu (fazowy prąd zasilający odbiornika mniejszy lub rowny 16 A). [16] PN-EN 61000-3-3:1997/A1:2002 (U) Kompatybilność elektromagnetyczna (EMC). Dopuszczalne poziomy. Ograniczanie wahań napięcia [17] PN-EN 61000-4-7:1998 Kompatybilność elektromagnetyczna (EMC). Metody badań i pomiarow. Ogólny przewodnik dotyczący pomiarów harmonicznych i interharmonicznych oraz stosowanych do tego celu przyrządow dla sieci zasilających i przyłączonych do nich urządzeń. [18] PN-EN 61000-4-11:1997 Kompatybilność elektromagnetyczna (EMC). Metody badań i pomiarow. Badania odporności na zapady napięcia,krotkie przerwy i zmiany napięcia. [19] PN-EN 61000-4-14:2002 Kompatybilność elektromagnetyczna (EMC). Metody badań i pomiarow. Badanie odporności na wahania napięcia. [20] PN-EN 61000-4-28:2004 Kompatybilność elektromagnetyczna (EMC). Metody badań i pomiarow. Badanie odporności na zmiany częstotliwości sieci zasilającej.
Authors: dr inż. Wiesława Malska, Politechnika Rzeszowska, Wydział Elektrotechniki i Informatyki, Katedra Energoelektroniki i Elektroenergetyki, al. Powstańców Warszawy 12, E-mail: wmalska@prz.edu.pl; dr inż. Anna Koziorowska, Uniwersytet Rzeszowski, Instytut Techniki, al. Rejtana 16c, 35-959 Rzeszów, E-mail: akozioro@univ.rzeszow.pl; dr inż. Dariusz Sobczyński, Politechnika Rzeszowska, Wydział Elektrotechniki i Informatyki, Katedra Energoelektroniki i Elektroenergetyki, al. Powstańców Warszawy 12, 35-959 Rzeszów, E-mail: dsobczyn@prz.edu.pl
Source & Publisher Item Identifier: PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 89 NR 10/2013
Published by Electrotek Concepts, Inc., PQSoft Case Study: Industrial Customer IEEE Std. 519 Compliance Evaluation, Document ID: PQS1003, Date: March 15, 2010.
Abstract: Utility power system harmonic problems can often be solved using a comprehensive approach including site surveys, harmonic measurements, and computer simulations.
This case study presents the results for an industrial customer IEEE Std. 519 compliance evaluation. The simulations were completed using the SuperHarm program. The results showed a harmonic resonance when the customer power factor correction capacitor banks were in service. The voltage distortion levels were mostly within the specified limits.
INTRODUCTION
An industrial customer IEEE Std. 519 compliance evaluation study was completed for the system shown in Figure 1. The simulation analysis was completed using the SuperHarm program. The accuracy of the simulation model was verified using three-phase and single-line-to-ground fault currents and other steady-state quantities.
The circuit modeled for the case involved a 12.5kV utility distribution substation supplying two 1,500 kVA customer step-down transformers. Each customer has a switchable 200 kVAr, 480-volt capacitor bank and a variety of nonlinear loads.
Figure 1 – Illustration of Oneline Diagram for Harmonic Current Cancellation Evaluation
SIMULATION RESULTS
Relevant utility system and customer data for the case included:
Short-circuit MVA at 12.4kV bus: 200.0 MVA Substation capacitor bank rating: 3.0 MVAr Feeder load: 5.0 MW Distribution feeder impedance: 0.2 Ω Short-circuit MVA at PCC: 158 MVA (Isc = 7,298 A) Customer capacitor bank ratings: 200 kVAr Miscellaneous linear load: 700 kVA Customer average maximum demand load: 974 kVA (IL = 45 A) Fluorescent lighting (ITHD = 21.7%): 200 kVA DC drive (ITHD = 35.3%): 250 hp PWM ASD (no choke – ITHD = 130.8%): 25 hp PWM ASD (with 3% choke – ITHD = 45.1%): 100 hp Switch mode power supplies (ITHD = 77.2%): 30 kVA
Figure 2 shows the results for the three frequency scan simulations. Case #1 was the base case with no capacitor banks included in the model. Case #2 was the case with the 200 kVAr capacitor banks on each customer 480 volt bus. Case #3 was the case with the 200 kVAr capacitor banks reconfigured as 4.7th harmonic filters. The parallel resonance for Case #2 was about 680 Hz.
Figure 2 – Simulated Frequency Response Characteristics
Table 1 summarizes the results for the three distortion simulations. The table includes the simulated voltage total harmonic distortion (THD) at the five buses for the three different operating conditions. Only one of the cases exceeded the voltage limitation of 5% THD.
Table 1 – Summary of the Simulated Voltage Distortion Results
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Table 2 shows the harmonic currents limits from IEEE Std. 519 that may be used for industrial customers. The ratio of the short-circuit MVA at the point of common coupling (PCC) to the average maximum demand load is approximately 162 (158 MVA / 974 kVA). That means that the fourth row of the table was used to evaluate the harmonic currents at the PCC for the three different operating conditions.
Table 2 – IEEE Std. 519 Current Limits for Utility Customers
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Table 3 summarizes the results of the harmonic current compliance analysis for the three simulated cases. The only condition that exceeded the limitation is the 11th harmonic component for Case #2 which represents the condition with the two 200 kVAr capacitor banks at the customer low voltage buses. The results for Case #3 show that converting the 200 kVAr capacitor banks into 4.7th harmonic filters reduced the harmonic current levels below the specified limitation.
Figure 3 shows the corresponding simulated point of common coupling (PCC) current waveform for Case #2. The waveform was created using an inverse DFT with 256 points per cycle.
Table 3 – Summary of Harmonic Current Limit Compliance
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Figure 3 – Simulation Results for Case #2
SUMMARY
This case study summarizes the results for an industrial customer IEEE Std. 519 compliance evaluation. The simulation results showed an 11th harmonic resonance when the customer power factor correction capacitor banks were in service. The voltage distortion levels were mostly within the specified limits.
The initial solution might seem to be to install an 11th harmonic filter; however, passive filters should be tuned below the lowest significant harmonic present. In this case, that was the 5th harmonic. Therefore, the current distortion evaluation shows that current distortion limits can be achieved by converting the customer capacitor banks into 4.7th harmonic filters.
REFERENCES
1. Power System Harmonics, IEEE Tutorial Course, 84 EH0221-2-PWR, 1984. 2. IEEE Recommended Practice for Monitoring Electric Power Quality,” IEEE Std. 1159-1995, IEEE, October 1995, ISBN: 1-55937-549-3. 3. IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems, IEEE Std. 519-1992, IEEE, ISBN: 1-5593-7239-7.
RELATED STANDARDS IEEE Std. 519-1992 IEEE Std. 1159-1995
GLOSSARY AND ACRONYMS ASD: Adjustable-Speed Drive CF: Crest Factor DFT: Discreet Fourier Transform DPF: Displacement Power Factor PCC: Point of Common Coupling PF: Power Factor PWM: Pulse Width Modulation TDD: Total Demand Distortion THD: Total Harmonic Distortion TPF: True Power Factor
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