Electrical Power Systems Quality, Third Edition

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Electrical Power Systems Quality, Third Edition

Electrical Power Systems Quality, Third Edition

Authors: Roger C. Dugan, Mark F. McGranaghan, Surya Santoso and H. Wayne Beaty

Published: January 2012

eISBN: 9780071761567 007176156X | ISBN: 9780071761550

Contents

Foreword

Acknowledgments

1 Introduction

1.1 What Is Power Quality?

1.2 Power Quality = Voltage Quality

1.3 Why Are We Concerned about Power Quality?

1.4 The Power Quality Evaluation Procedure

1.5 Who Should Use This Book

1.6 Overview of the Contents

2 Terms and Definitions

2.1 Need for a Consistent Vocabulary

2.2 General Classes of Power Quality Problems

2.3 Transients

2.3.1 Impulsive Transient

2.3.2 Oscillatory Transient

2.4 Long-Duration Voltage Variations

2.4.1 Overvoltage

2.4.2 Undervoltage

2.4.3 Sustained Interruptions

2.5 Short-Duration Voltage Variations

2.5.1 Interruption

2.5.2 Sags (Dips)

2.5.3 Swells

2.6 Voltage Imbalance

2.7 Waveform Distortion

2.8 Voltage Fluctuation

2.9 Power Frequency Variations

2.10 Power Quality Terms

2.11 Ambiguous Terms

2.12 CBEMA and ITI Curves

2.13 References

3 Voltage Sags and Interruptions

3.1 Utility Distribution System Designs

3.1.1 Four-Wire Multi-Grounded Neutral Systems

3.1.2 Three-Wire Delta Systems

3.1.3 European-Style Distribution Systems

3.1.4 Radial Distribution Configuration/Structure

3.2 Sources of Sags and Interruptions

3.3 Estimating Voltage Sag Performance

3.3.1 Area of Vulnerability

3.3.2 Equipment Sensitivity to Voltage Sags

3.3.3 Transmission System Sag Performance Evaluation

3.3.4 Utility Distribution System Sag Performance Evaluation

3.4 Fundamental Principles of Protection

3.5 Solutions at the End-User Level

3.5.1 Ferroresonant Transformers

3.5.2 Magnetic Synthesizers

3.5.3 Active Series Compensators

3.5.4 On-Line UPS

3.5.5 Standby UPS

3.5.6 Hybrid UPS

3.5.7 Motor-Generator Sets

3.5.8 Flywheel Energy Storage Systems

3.5.9 Superconducting Magnetic Energy Storage (SMES) Devices

3.5.10 Static Transfer Switches and Fast Transfer Switches

3.6 Evaluating the Economics of Different Ride-Through Alternatives

3.6.1 Estimating the Costs for the Voltage Sag Events

3.6.2 Characterizing the Cost and Effectiveness for Solution Alternatives

3.6.3 Performing Comparative Economic Analysis

3.7 Motor-Starting Sags

3.7.1 Motor-Starting Methods

3.7.2 Estimating the Sag Severity during Full-Voltage Starting

3.8 Utility System Fault-Clearing Issues

3.8.1 Overcurrent Coordination Principles

3.8.2 Fuses

3.8.3 Reclosing

3.8.4 Fuse Saving

3.8.5 Reclosers with Pulse-Closing Technology

3.8.6 Reliability

3.8.7 Impact of Eliminating Fuse Saving

3.8.8 Increased Sectionalizing

3.8.9 Midline or Tap Reclosers

3.8.10 Instantaneous Reclosing

3.8.11 Single-Phase Tripping

3.8.12 Current-Limiting Fuses

3.8.13 Adaptive Relaying

3.8.14 Ignoring Third-Harmonic Currents

3.8.15 Utility Fault Prevention

3.8.16 Fault Locating

3.9 Fault Locating Using Voltage and Current Measurements

3.9.1 Impedance-Based Fault Location Methods

3.9.2 Locating Incipient Faults

3.9.3 Fault Current Profile

3.10 References

4 Transient Overvoltages

4.1 Sources of Transient Overvoltages

4.1.1 Capacitor Switching

4.1.2 Magnification of Capacitor-Switching Transients

4.1.3 Restrikes During Capacitor Deenergizing

4.1.4 Lightning

4.1.5 Ferroresonance

4.1.6 Other Switching Transients

4.2 Principles of Overvoltage Protection

4.3 Devices for Overvoltage Protection

4.3.1 Surge Arresters and Transient Voltage Surge Suppressors

4.3.2 Isolation Transformers

4.3.3 Low-Pass Filters

4.3.4 Low-Impedance Power Conditioners

4.3.5 Utility Surge Arresters

4.4 Utility Capacitor-Switching Transients

4.4.1 Switching Times

4.4.2 Preinsertion Resistors

4.4.3 Synchronous Closing

4.4.4 Capacitor Location

4.5 Utility System Lightning Protection

4.5.1 Shielding

4.5.2 Line Arresters

4.5.3 Low-Side Surges

4.5.4 Cable Protection

4.5.5 Scout Arrester Scheme

4.6 Managing Ferroresonance

4.7 Switching Transient Problems with Loads

4.7.1 Nuisance Tripping of Adjustable-Speed Drives (ASDs)

4.7.2 Transients from Load Switching

4.7.3 Transformer Energizing

4.8 Computer Tools for Transients Analysis

4.9 References

5 Fundamentals of Harmonics

5.1 Harmonic Distortion

5.2 Voltage versus Current Distortion

5.3 Harmonics versus Transients

5.4 Power System Quantities under Nonsinusoidal Conditions

5.4.1 Active, Reactive, and Apparent Power

5.4.2 Power Factor: Displacement and True

5.4.3 Harmonic Phase Sequences

5.4.4 Triplen Harmonics

5.5 Harmonic Indices

5.5.1 Total Harmonic Distortion

5.5.2 Total Demand Distortion

5.6 Harmonic Sources from Commercial Loads

5.6.1 Single-Phase Power Supplies

5.6.2 Fluorescent Lighting

5.6.3 Adjustable-Speed Drives for HVAC and Elevators

5.7 Harmonic Sources from Industrial Loads

5.7.1 Three-Phase Power Converters

5.7.2 Arcing Devices

5.7.3 Saturable Devices

5.8 Locating Harmonic Sources

5.9 System Response Characteristics

5.9.1 System Impedance

5.9.2 Capacitor Impedance

5.9.3 Parallel Resonance

5.9.4 Series Resonance

5.9.5 Effects of Resistance and Resistive Load

5.10 Effects of Harmonic Distortion

5.10.1 Impact on Capacitors

5.10.2 Impact on Transformers

5.10.3 Impact on Motors

5.10.4 Impact on Telecommunications

5.10.5 Impact on Energy and Demand Metering

5.11 Interharmonics

5.12 References

5.13 Bibliography

6 Applied Harmonics

6.1 Harmonic Distortion Evaluations

6.1.1 Concept of Point of Common Coupling

6.1.2 Harmonic Evaluations on the Utility System

6.1.3 Harmonic Evaluation for End-User Facilities

6.2 Principles for Controlling Harmonics

6.2.1 Reducing Harmonic Currents in Loads

6.2.2 Filtering

6.2.3 Modifying the System Frequency Response

6.3 Where to Control Harmonics

6.3.1 On Utility Distribution Feeders

6.3.2 In End-User Facilities

6.4 Harmonic Studies

6.4.1 Harmonic Study Procedure

6.4.2 Developing a System Model

6.4.3 Modeling Harmonic Sources

6.4.4 Computer Tools for Harmonics Analysis

6.4.5 Harmonic Analysis by Computer—Historical Perspective

6.5 Devices for Controlling Harmonic Distortion

6.5.1 In-Line Reactors or Chokes

6.5.2 Zigzag Transformers

6.5.3 Passive Filters

6.5.4 Active Filters

6.6 Harmonic Filter Design: A Case Study

6.7 Case Studies

6.7.1 Evaluation of Neutral Loading and Transformer Derating

6.7.2 Interharmonics Caused by Induction Furnaces

6.8 Standards on Harmonics

6.8.1 IEEE Standard 519-1992

6.8.2 Overview of IEC Standards on Harmonics

6.8.3 IEC 61000-2-2

6.8.4 IEC 61000-3-2 and IEC 61000-3-4

6.8.5 IEC 61000-3-6

6.8.6 NRS 048-02

6.8.7 EN 50160

6.9 References

6.10 Bibliography

7 Long-Duration Voltage Variations

7.1 Principles of Regulating the Voltage

7.2 Devices for Voltage Regulation

7.2.1 Utility Step-Voltage Regulators

7.2.2 Ferroresonant Transformers

7.2.3 Electronic Tap-Switching Regulators

7.2.4 Magnetic Synthesizers

7.2.5 On-Line UPS Systems

7.2.6 Motor-Generator Sets

7.2.7 Static Var Compensators

7.3 Utility Voltage Regulator Application

7.3.1 Line Drop Compensator

7.3.2 Regulators in Series

7.4 Capacitors for Voltage Regulation

7.4.1 Shunt Capacitors

7.4.2 Series Capacitors

7.5 End-User Capacitor Application

7.5.1 Location for Power Factor Correction Capacitors

7.5.2 Voltage Rise

7.5.3 Reduction in Power System Losses

7.5.4 Reduction in Line Current

7.5.5 Displacement Power Factor versus True Power Factor

7.5.6 Selecting the Amount of Capacitance

7.6 Regulating Utility Voltage with Distributed Resources

7.7 Flicker

7.7.1 Sources of Flicker

7.7.2 Mitigation Techniques

7.7.3 Quantifying Flicker

7.8 References

7.9 Bibliography

8 Power Quality Benchmarking

8.1 Introduction

8.2 Benchmarking Process

8.3 RMS Voltage Variation Indices

8.3.1 Characterizing RMS Variation Events

8.3.2 RMS Variation Performance Indices

8.3.3 SARFI for the EPRI DPQ Project

8.3.4 Example Index Computation Procedure

8.3.5 Utility Applications

8.4 Harmonics Indices

8.4.1 Sampling Techniques

8.4.2 Characterization of Three-Phase Harmonic Voltage Measurements

8.4.3 Definition of Harmonic Indices

8.4.4 Harmonic Benchmark Data

8.4.5 Seasonal Effects

8.5 Power Quality Contracts

8.5.1 RMS Variations Agreements

8.5.2 Harmonics Agreements

8.5.3 Example Contract

8.6 Power Quality Insurance

8.6.1 Overview of Power Quality Insurance Concept

8.6.2 Designing an Insurance Policy

8.6.3 Adjusting for PQ Investment Costs

8.7 Power Quality State Estimation

8.7.1 General Approach

8.7.2 Number of Monitors

8.7.3 Estimating RMS Variations

8.7.4 Simulation Engine Requirements

8.8 Including Power Quality in Distribution Planning

8.8.1 Planning Process

8.8.2 Risk versus Expected Value

8.8.3 System Simulation Tools

8.8.4 Fault Incidence Rates

8.8.5 Overcurrent Device Response

8.8.6 Customer Damage Costs

8.9 References

8.10 Bibliography Distributed Generation and Power Quality

9 Distributed Generation and Power Quality

9.1 Resurgence of DG

9.1.1 Perspectives on DG Benefits

9.1.2 Perspectives on Interconnection

9.2 DG Technologies

9.2.1 Reciprocating Engine Genset

9.2.2 Combustion (Gas) Turbines

9.2.3 Fuel Cells

9.2.4 Wind Turbines

9.2.5 Photovoltaic Systems

9.3 Interface to the Utility System

9.3.1 Synchronous Machines

9.3.2 Asynchronous (Induction) Machines

9.3.3 Electronic Power Inverters

9.4 Power Quality Issues

9.4.1 Sustained Interruptions

9.4.2 Voltage Regulation

9.4.3 Harmonics

9.4.4 Voltage Sags

9.5 Operating Conflicts

9.5.1 Utility Fault-Clearing Requirements

9.5.2 Reclosing

9.5.3 Interference with Relaying

9.5.4 Voltage Regulation Issues

9.5.5 Harmonics

9.5.6 Islanding

9.5.7 Ferroresonance

9.5.8 Shunt Capacitor Interaction

9.5.9 Transformer Connections

9.6 DG on Low-Voltage Distribution Networks

9.6.1 Fundamentals of Network Operation

9.6.2 Summary of Network Interconnection Issues

9.6.3 Integration Techniques for DG on Networks

9.7 Siting DG

9.8 Interconnection Standards

9.8.1 Industry Standards Efforts

9.8.2 Interconnection Requirements

9.8.3 A Simple Interconnection

9.8.4 A Complex Interconnection

9.9 Summary

9.10 References

9.11 Bibliography

10 Wiring and Grounding

10.1 Resources

10.2 Definitions

10.3 Reasons for Grounding

10.4 Typical Wiring and Grounding Problems

10.4.1 Problems with Conductors and Connectors

10.4.2 Missing Safety Ground

10.4.3 Multiple Neutral-to-Ground Connections

10.4.4 Ungrounded Equipment

10.4.5 Additional Ground Rods

10.4.6 Ground Loops

10.4.7 Insufficient Neutral Conductor

10.5 Solutions to Wiring and Grounding Problems

10.5.1 Proper Grounding Practices

10.5.2 Ground Electrode (rod)

10.5.3 Service Entrance Connections

10.5.4 Panel Board

10.5.5 Isolated Ground

10.5.6 Separately Derived Systems

10.5.7 Grounding Techniques for Signal Reference

10.5.8 More on Grounding for Sensitive Equipment

10.5.9 Summary of Wiring and Grounding Solutions

10.6 Bibliography

11 Power Quality Monitoring

11.1 Monitoring Considerations

11.1.1 Monitoring as Part of a Facility Site Survey

11.1.2 Determining What to Monitor

11.1.3 Choosing Monitoring Locations

11.1.4 Options for Permanent Power Quality Monitoring Equipment

11.1.5 Disturbance Monitor Connections

11.1.6 Setting Monitor Thresholds

11.1.7 Quantities and Duration to Measure

11.1.8 Finding the Source of a Disturbance

11.2 Historical Perspective of Power Quality Measuring Instruments

11.3 Power Quality Measurement Equipment

11.3.1 Types of Instruments

11.3.2 Wiring and Grounding Testers

11.3.3 Multimeters

11.3.4 Digital Cameras

11.3.5 Oscilloscopes

11.3.6 Disturbance Analyzers

11.3.7 Spectrum Analyzers and Harmonic Analyzers

11.3.8 Combination Disturbance and Harmonic Analyzers

11.3.9 Flicker Meters

11.3.10 Smart Power Quality Monitors

11.3.11 Transducer Requirements

11.4 Assessment of Power Quality Measurement Data

11.4.1 Off-Line Power Quality Data Assessment

11.4.2 On-Line Power Quality Data Assessment

11.5 Application of Intelligent Systems

11.5.1 Basic Design of an Expert System for Monitoring Applications

11.5.2 Example Applications of Expert Systems

11.5.3 Future Applications

11.5.4 Power Quality Monitoring and the Internet

11.5.5 Summary and Future Direction

11.6 Power Quality Monitoring Standards

11.6.1 IEEE 1159: Guide for Power Quality Monitoring

11.6.2 IEC 61000–4–30: Testing and Measurement Techniques—Power Quality Measurement Methods

11.7 References

11.8 Bibliography

Index