Power Quality & Quality of Supply A Global Continuously Developing Engineering Challenge

Published by Terry Chandler, A Power Quality Practitioner ™ for +30 years,

Director of Engineering Power Quality Thailand LTD/Power Quality Inc. USA,

Consultant for Dranetz Corporation USA (Asia business Unit General Manager)

Contact TerryC@powerquality.org

What is Power Quality (PQ)?

• The characteristics of the supply voltage and the electrical system that affect the performance of the load.
  
• The characteristics of the load that affect the electrical supply system and/or other loads. (TerryC. 1992)
  

What is Quality of Supply (QOS)?

• The characteristics of the supply voltage that affect the performance of the load.
  
• The characteristics of the electrical distribution system that affects the electrical loads. (Transformer size and distance to the loads)
  

Power Quality Definition?

• There are many more definitions from IEC, IEEE, Various PQ engineers and experts.
  
• PQ is a complex engineering & economic situation that is constantly changing due to technology and political environment changes. (TerryC. 2006)
  

PQ problems (costs) vs Power passing thru a semiconductor switch

Semiconductor Sales vs PQ

Power Reliability vs Power Quality

• Power Reliability is the presence of voltage at the meter point.
  
• Power Quality is the value of the voltage (and other PQ parameters) as a percent of nominal at the meter. – Mr. Phil Sarikas, Intel Corporation 4/97
  

Quality of Supply Parameters (Utility)

• RMS voltage, Sags (dips) and Surges (swells) – Disturbances
  
• Voltage transients (slow, medium, and fast)
  
  • Lightning and switching transients that damage sensitive electronic loads
    
• Sinewave – wave shape-harmonics – System losses
  
• Voltage imbalance – phase differences – System losses
  
• Flicker- small periodic voltage variations at frequencies lower than ½ fundamental-The only parameter that affects people directly
  
• Frequency Variations
  
• Power Factor? System losses
  

Source of most common voltage sag from utility distribution system or transmission or generation

A fault on transmission system

Voltage Sag Example (QOS)

Power Quality Parameters User Side

• RMS voltage, Sag (dips) and surges (swells)
  
• Voltages transients (slow, fast, and extremely fast)
  
• Sinewave – wave shape – harmonics (Voltage and current)
  
• Voltage imbalance (phase imbalance) (Voltage and current)
  
• Flicker- small periodic voltage variations at frequencies lower than ½ fundamental. (current)
  
  • The only parameter that affects people directly
    
• Internal electrical system design and construction.
  
• Grounding /Earthing internal. (Ground loops and current in the ground conductor.
  
• Waveshapes, Harmonics, Interharmonics (current)
  

Source of the PQ issues?

In PQI’s 30 years of experience and data shows:

• 80% of the PQ issues are on the customer side of the meter.
  
• 80% of the $ losses are caused by the 20% of the PQ issues from the utility side of the meter.
  
• Majority of the issues from utility are voltage sags/short outages, flicker and harmonics caused by other loads.
  
• Voltage transients include decaying ringwaves (PF cap switching)
  
• Flicker usually caused by steel mill loads but now maybe from wind turbines
  

Power Quality is a constantly changing situation of varying loads, varying generation types, varying weather.

• For the first 20 years it was the loads changing in sensitivity to normal electrical distribution operations.
  
• Loads changing from incandescent lamps and motors to new technologies and Invertor (VFD,VSD’s) motor drives
  
• Generation changing from rotary to invertor-based renewables.
  
• Remote generation
  
• Harmonics causing losses
  
• Government influence/mandates of SmartGrid
  

Influence on Power Quality due to drive for more energy efficient loads.

• Lighting technology
  
  • Incandescent bulbs to Compact Fluorescent to LED
    
• Motor Control technology
  
  • Voltage control to SCR control to High Power Switching
    
• Power Switching technology for heating
  

Today Power Quality is more about data/information. (SmartGrid)

• SmartGrid ( 7,250,000 results from a Google search)
  
• A SmartGrid is an electrical grid which includes a variety of operational and energy measures including smart meters, smart appliances, renewable energy resources, and energy efficiency resources.
  
• What does Power Quality have to do with SmartGrid?
  

Data Integrated by Power Quality Monitoring System at Con Edison

• Transmission Feeders
  
  • Digital Fault Recorders
    
• Area Substation Transformers
  
  • Power Quality Monitors
    
  • Event Correlation with SCADA Breaker Operations
    
• Network Distribution Feeders
  
  • Digital Relays
    
  • Event Correlation with SCADA Breaker Operations
    
• Area Substation Capacitors
  
  • Indirect: PQ Monitors
    
  • Direct: Some Digital Relays
    
• Secondary Networks
  
  • Power Quality Monitors
    
• Unit Substation Transformers
  
  • Power Quality Monitoring
    
  • Phasor Measurement Sensors during Network Intermesh
    
  • Station Battery Sensors
    
• Long Island City Smart Meters
  
  • Energy and Power Quality Data Logs
    
• High Tension Remote Monitoring
  
  • Power and power quality monitoring
    
• Distribution and Transmission SCADA
  
  • Automatic momentary interruption analysis and correction with IEDs
    

Energy Efficiency and Power Quality

• There is a worldwide movement to increase the energy efficiency of loads.
  
• According to the International Energy Association, electric motors consume 45 percent of the total energy in the world. Lighting energy consumption is a distant second at 19 percent. https://www.iea.org/
  
• Energy efficiency is the one energy resource all countries possess in abundance.
  

Global Impact of Energy Efficiency

Electrical Energy Efficiency

• Same amount of work in the same amount of time with less Kilowatts. (KWhr)
  

Load Categories

• Industrial
  
  • Motors, lighting, building envelope, electronics
    
• Commercial
  
  • Lighting, building envelope, electronics
    
• Consumer
  
  • Appliances, lighting, building envelope
    
• Government
  

Parameters of Electrical Usage

• Voltage stability
  
• Voltage imbalance
  
• Amps to determine load characteristics
  
• Watts, KW, KWhr
  
• Power Factor
  
• Maximum demand
  
• Time of day usage
  
• Economic losses and return on investment require data $$$$$
  

The Basics of Energy Savings

• Motors
  
  • VFD/VSD reduce the energy not needed once the load is started
    
  • Improve the control by electronic switching
    
• Lighting
  
  • Change in technologies
    
    • Incandescent – Fluorescent – LED – specialty
      
• Electronic loads
  
  • Increased integration of semiconductors
    
• Temperature
  
  • Insulation, control, and technology
    

The Relationship Electricity usage to Power Quality Situations (parameters)

• As energy efficiency of loads increases (decreases), it changes the sensitivity to PQ parameters and increases (decreases) the generation of harmonics
  

Computer Power Supplies (AC to DC)

• Linear power supplies change to Switch mode.
  
  • Voltage operating range went from +/- 5% to universal voltage 90vac to 240vac
    
  • More sensitive to transients
    
  • Generate more harmonics
    
• Next generation
  
  • PF corrected
    
  • Lower Ithd but at higher order harmonics
    

Lighting (22%)

• Incandescent lights to solid state ballast fluorescent lights
  
  • Sensitivity to voltage reduced
    
  • Increase in harmonics
    

• Next, LED lights
  
  • Decrease in harmonics
    
  • Decrease sensitivity to Voltage?
    

Lamp Efficiency Comparison and PQ Sensitivity

Light Dimmers

• Lowers power used
  
• Increases Harmonics
  
• Sensitive to voltage transients
  
• Sensitive to voltage sags
  
  • Light blinks
    

Solid State Lights (SSL)

• Significant energy savings
  
• Sensitive to voltage transients
  
• AC to DC converter generates harmonics
  

Motors

• 70% of electrical load (Industrial) 45% of global load
  
• High Efficiency motors
  
• Electronic controls for existing motors
  
  • Variable Speed Drives (VFD)
    
  • Variable Frequency Drives (VSD)
    
  • Soft start
    

High Efficiency Motors

Add VFD (VSD) to Motors

• Variable speed drives
  
  • Sensitive
    
    • Sags
      
    • Phase shifts
      
    • Transients
      
    • Imbalance
      
• Generates harmonics
  

How a VFD or VSD works?

Drivers for Change in PQ and Efficiency

• Cost savings
  
• Improving control over processes
  
• Energy efficiency (Green World)
  
• Reduce size and weight of equipment by lowering power consumption
  
• Advances in technology
  
  • Semiconductor
    
  • Materials of all types
    
    • Insulation and conductors
      

Conclusions

• Power Quality and Energy efficiency are linked by the changing technologies
  
• The Changing technologies are a global situation.
  
  • The only constant is the varying rate of change!
    
• Effective engineering depends on global information and technical resources
  
• I have been an IEEE member for more than 30 years! It is a global organization that has provides consistent and valuable resource data for wide variety of electrical subjects