Welcome To Our Power Quality Blog
Power Quality Blog has been created by Power Quality (Thailand) Co., Ltd. to share knowledge, and experience in solving power quality challenges. We focus on a wide range of power quality related issues, such as harmonics, transients, voltage variations, flicker, poor power factor, voltage sags and swells, and unbalance electrical loads etc.
PQ Blog also includes case studies, power standards, power protection, PQ meters, PQ technologies, PQSynergy™ papers and much more.
Latest from the Blog
Load stepping, power source switching and other tests required during the commissioning and troubleshooting of mission critical facilities presents unique challenges to the average PQ analyzer, but Dranetz doesn’t make average PQ analyzers. Most PQ analyzers can’t reliably capture the step load changes, don’t have a large enough recording buffer, can’t capture the effects onContinue reading “Dranetz HDPQ Generator & Mission Critical Applications”
Published by Kerim Ozer, Senior Electrical Engineer, Enspec Power Ltd. Email: email@example.com A technical review of how passive harmonic filter types have an impact on network impedance profiles in terms of damping. A review of a harmonic filter design study was carried out for an industrial Plant, which included a total capacity of >100MW smelters,Continue reading “Passive Harmonic Filter Design”
INERTIA DRIVE (ID) THE NEXT GENERATION FLYWHEEL The Inertia Drive technology is based on the flywheel mechanical battery concept that stores kinetic energy in the form of a rotating mass. Our innovations focus on design, assembly and manufacturing process. Solar and wind power only produce when the wind is blowing or the sun is shining.Continue reading “OXTO Energy: A New Generation of Flywheel Energy Storage”
Dranetz Summer 2021 Live Web Training
Dranetz Free Live Web Based ‘How To’ and Informational Training
Dranetz factory product training gives you the head start you need to hit the ground running. You’ve made the best choice by purchasing a Dranetz instruments and software. Now maximize your investment by ensuring you (or your team) have fully optimized the usage of our superior tools.
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Electrotek® Concepts | PQView®
What is PQView 4?
Developed in collaboration with EPRI® and Electric Utility partners globally, PQView 4 is the flagship product of Electrotek Concepts, Inc.—built from the ground up to be the best-in-class Power Quality data concentrator and analysis software. PQView can acquire and store data from multiple sources, and provide powerful data analytics and reporting capabilities via a responsive web enabled user interface.
For more information, you can visit electrotek.com
Users Group Meeting October 19th-20th, 2021
PQView® is a Microsoft Windows server application for collecting, processing, and building databases of electric power measurements. Developed in cooperation with EPRI®, PQView has evolved into a comprehensive system for centralizing data from many different types of metering systems including power quality monitors, digital fault recorders, microprocessor relays, and SCADA systems. PQWeb enables web browsers to query measurements stored in a PQView database via a corporate intranet or the Internet. This virtual Users Group meeting includes both formal presentations and hands-on computer workshop lessons that focus on the past, present, and future developments of both PQView and PQWeb.
Electrotek holds three different regional Users Group Meetings across the world. There is an annual North American Users Group meeting, and a European Users Group Meeting and Asian Users Group Meeting every year and a half. These Users Group Meetings are invite-only opportunities for regional users of PQView to get together and share their experiences with the software.
The meetings are normally scheduled to have an optional training session on the first day or two and is followed up by the actual Users Group meeting. Historically, the Users Group meetings are a mix of Electrotek discussing new features in the software along with upcoming features being worked on along with end users providing case studies that illustrate how PQView is helping them with their daily work. These meetings are also an excellent opportunity to network with other users.
Fall 2021 Virtual Users Group Meeting Schedule
Based on user feedback about the ability/desire to travel, the 2021 PQView Users Group Meetings will be held virtually. We strive to resume in person meetings during the first half of 2022.
All times are Eastern US time:
October 19th, 2021 – PQView Workshop:
- 10:45 am to 11:00 am – Convene
- 11:00 am to 12:00 pm – Overview of PQView Components Followed by Installation
- 12:00 pm to 1:00 pm – PQView Upgrade and Troubleshooting – Logging: Log location, adjusting logging levels, etc. – Troubleshooting guide overview
- 1:00 pm to 2:00pm – Break
- 2:00 pm to 3:00 pm – PQView Administrator Website: profiles, users, resources, and permissions
- 3:00 pm to 4:00 pm – PQWeb’s Administration Functions – Overview of PQView SDKs (Web, Data Layer, SQL Interface) – Configuring AD for Resources and for Authentication – FAQ Session: Most Common Issues & Solutions
- 4:00 pm to 4:30 pm – Adjourn/Q&A Session
October 20th, 2021 – PQView Users Group Meeting Agenda:
- 10:45 am to 11:00 am – Convene
- 11:00 am to 11:30 am – Welcome to the 2021 PQView Users Group Meeting
- 11:30 am to 12:30 pm – New PQView Features in the Past Year
- 12:30 am to 1:00 pm – Data Handlers, PQDR updates, Monarch Functionality, Importing Models
- 1:00 pm to 2:00pm – Break
- 2:00 pm to 2:30 pm – Customer Presentation #1
- 2:30 pm to 3:00 pm – Customer Presentation #2
- 3:00 pm to 3:45 pm – New Features for Customers in the Pipeline
- 3:45 pm to 4:00 pm – Closing and Q&A Session
Knowing IEC 61000-4-30 Class A
IEC 61000-4-30 Performance Classes
The IEC 61000-4-30 defines 3 performance classes as follow:
- Class A – must to comply to the highest performances and accuracy level to obtain repeatable and comparable results
- Class S – accuracy levels are less stringent. Class S Power quality analyzers can be used for statistical surveys and contractual application where comparable measurement are not required.
- Class B (obsolete) – This class was introduced at the 1st and 2nd editions of the standard to avoid making may instrument obsolete. In this class the standard required that the measurement method and accuracy will be defined by the manufacturer in the instrument datasheet. In the 3rd addition, this performance class was removed.
Time Aggregation Intervals
The IEC 61000-4-30 class A defines several aggregation intervals:
- 10/12 cycles (~200ms) at 50/60Hz respectively. The interval time varies with actual frequency.
- 150/180cycles (~3sec) at 50/60Hz respectively. The interval time varies with actual frequency.
- 10min interval begins on an absolute 10min time
- 2 hours interval begins on an absolute even 2h time.
In the 2nd edition of the standard Re-synchronization technique was introduced to align the frequency based aggregations (10/12 cycles, 150/180 cycles) with time based aggregations (10min and 2 hours). The re-synchronization happens exactly every absolute 10min and deviation of the 10/12 cycles block are overlap as illustrated in the image below:
Power Quality Parameters Defined in the Standard
Following are the parameters defined in the IEC 61000-4-30 standard:
- Power frequency
- Magnitude of supply voltage
- Flicker (by reference to IEC 61000-4-15)
- Supply dips/swells
- Voltage Interruptions
- Voltage unbalance
- Voltage harmonics (by reference to IEC 61000-4-7)
- Voltage Inter-harmonics (by reference to IEC 61000-4-7)
- Mains signaling
- Under- and over-deviation
In the 3rd addition the following parameter was introduced:
- Rapid voltage changes
- Flicker class F1
- Magnitude of the current
- Current unbalance
- Current harmonics (by reference to IEC 61000-4-7)
- Current interharmonics (by reference to IEC 61000-4-7)
Recording of current along with voltage during events
Examples of IEC 61000-4-30 Class A requirements
Measurement resolution of Power frequency is set to 10sec with uncertainty of 10mHz over measuring ranges of 42.5 – 57.5Hz / 51 – 69Hz at 50/60Hz respectively. Aggregation intervals are not mandatory for this section. In some application the required resolution is not sufficient and higher resolution as 1 cycle (power generation), 10/12 cycles (wind turbines) and 1sec (in some national standard) are required. The image below shows reading variations of the same signal measured in different resolution:
Note that the IEEE C37.118.1 suggest different method to calculate power frequency at higher resolution.
Magnitude of Supply Voltage
The magnitude of the supply voltage is the RMS values over 10/12 cycles (~200msec) time interval for a 50/60 Hz power systems respectively. Aggregations of 150/180 cycles (~3sec), 10min and 2 hours are also required. Measurement uncertainty is set to 0.1% of Udin (the declared input voltage) over the range of 10 – 150 % of Udin.
It is important to note that the standard does not specify any requirement for the recording resolution. Hence, it is highly important to look at the manufacturer specifications to verify its recording capability. In a typical PQA (Power Quality Analyzer) without a continuous waveform recording, the recording period depends on the recording resolution. Therefore, recording of 1 week can be done only at 10min resolution. Increasing the resolution to 10/12 cycle will shorten the recording period to a few minutes only.
It is also important to note that this measurement method is used for quasi-stationary signals and not for the detection of power quality events such dips (Sags), swells, interruptions, transient and RVC (Rapid Voltage Changes).
In The example below: the left side shows 1/2 cycle RMS values (colored in red), the right side shows 10 cycles RMS values (colored in black). Move the handle to see the influence of the resolution on the measurement outputs:
Power Quality Events
Dips (Sags), swells, interruptions, transient and RVC events must be measured in a sliding window of 1 cycle width updated every 1/2 cycle and synchronized to zero crossing as illustrated below:
Events evaluation is made by two parameters: voltage deviation from the reference voltage and duration.
The IEC 61000-4-30 standard doesn’t specify what should be recorded when event happens or the recording duration before and after the event.
When looking at manufacturers’ specification it is important to understand what the instrument recording capabilities are. For instance, low cost PQAs will only record the URMS(1/2) of the effected phase for a very short duration, while more advanced analyzers will record both the URMS(1/2) and IRMS(1/2) of all phases (both phase to phase and phase to ground). Furthermore, in many cases it is important to record the waveform signal itself before during and after the event. In this instance, it is important to understand what the waveform recording resolution capabilities are, and how long such high resolution recording can hold.
Having a power quality analyzer with a continuous waveform recording eliminate the need to set any trigger or threshold to capture the event and recording both RMS1/2 and waveform at high resolution continuously.
Harmonics and Interharmonics
IEC 61000-4-30 adopt the 10/12 cycles gapless harmonic subgroup measurement from the IEC 61000-4-7. It means that the FFT window is 10/12 cycle and the harmonic components output (bins) are at 5Hz resolution. The output component for each 5Hz bin is grouped according to the image below:
It means that the actual output have 50 harmonics values and 50 interharmonics values. Aggregations of 150/180 cycles (~3sec), 10min and 2 hours are also required.
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Ontario Wind Turbine Fail, Canada
Photos by Thomas Szollossy, August 2021.