Switching in Electrical Transmission and Distribution Systems

Contents

Preface

1 Switching in Power Systems

1.1 Introduction

1.2 Organization of this Book

1.3 Power-System Analysis

1.4 Purpose of Switching

1.4.1 Isolation and Earthing

1.4.2 Busbar-Transfer Switching

1.4.3 Load Switching

1.4.4 Fault-Current Interruption

1.5 The Switching Arc

1.6 Transient Recovery Voltage (TRV)

1.6.1 TRV Description

1.6.2 TRV Composed of Load- and Source-Side Contributions

1.7 Switching Devices

1.8 Classification of Circuit-Breakers

References

2 Faults in Power Systems

2.1 Introduction

2.2 Asymmetrical Current

2.2.1 General Terms

2.2.2 DC Time Constant

2.2.3 Asymmetrical Current in Three-Phase Systems

2.3 Short-Circuit Current Impact on System and Components

2.4 Fault Statistics

2.4.1 Occurrence and Nature of Short-Circuits

2.4.2 Magnitude of Short-Circuit Current

References

3 Fault-Current Breaking and Making

3.1 Introduction

3.2 Fault-Current Interruption

3.3 Terminal Faults

3.3.1 Introduction

3.3.2 Three-Phase Current Interruption

3.4 Transformer-Limited Faults

3.4.1 Transformer Modelling for TRV Calculation

3.4.2 External Capacitances

3.5 Reactor-Limited Faults

3.6 Faults on Overhead Lines

3.6.1 Short-Line Faults

3.6.2 Long-Line Faults

3.7 Out-of-Phase Switching

3.7.1 Introduction

3.7.2 Switching between Generator and System

3.7.3 Switching between Two Systems

3.8 Fault-Current Making

3.8.1 Impact of Making a Short-Circuit Current on the Circuit-Breaker

3.8.2 Switching-Voltage Transients at Making in Three-Phase Systems

References

4 Load Switching

4.1 Normal-Load Switching

4.2 Capacitive-Load Switching

4.2.1 Introduction

4.2.2 Single-Phase Capacitive-Load Switching

4.2.3 Three-Phase Capacitive-Load Switching

4.2.4 Late Breakdown Phenomena

4.2.5 Overhead-Line Switching

4.2.6 Capacitor-Bank Energization

4.3 Inductive-Load Switching

4.3.1 Current Chopping

4.3.2 Implication of Current Chopping

4.3.3 Inductive-Load Switching Duties

References

5 Calculation of Switching Transients

5.1 Analytical Calculation

5.1.1 Introduction

5.1.2 Switching LR Circuits

5.1.3 Switching RLC Circuits

5.2 Numerical Simulation of Transients

5.2.1 Historical Overview

5.2.2 The Electromagnetic Transients Program

5.2.3 Overview of Electrical Programs for Transient Simulation

5.3 Representation of Network Elements when Calculating Transients

References

6 Current Interruption in Gaseous Media

6.1 Introduction

6.2 Air as an Interrupting Medium

6.2.1 General

6.2.2 Fault-Current Interruption by Arc Elongation

6.2.3 Arc Chutes

6.2.4 Arcs in Open Air

6.2.5 Current Interruption by Compressed Air

6.3 Oil as an Interrupting Medium

6.3.1 Introduction

6.3.2 Current Interruption in Bulk-Oil Circuit-Breakers

6.3.3 Current Interruption in Minimum-Oil Circuit-Breakers

6.4 Sulfur Hexafluoride (SF6) as an Interrupting Medium

6.4.1 Introduction

6.4.2 Physical Properties

6.4.3 SF6 Decomposition Products

6.4.4 Environmental Effects of SF6

6.4.5 SF6 Substitutes

6.5 SF6 – N2 Mixtures

References

7 Gas Circuit-Breakers

7.1 Oil Circuit-Breakers

7.2 Air Circuit-Breakers

7.3 SF6 Circuit-Breakers

7.3.1 Introduction

7.3.2 Double-Pressure SF6 Circuit-Breakers

7.3.3 Puffer-Type SF6 Circuit-Breakers

7.3.4 Self-Blast SF6 Circuit-Breakers

7.3.5 Double-Motion Principle

7.3.6 Double-Speed Principle

7.3.7 SF6 Circuit-Breakers with Magnetic Arc Rotation

References

8 Current Interruption in Vacuum

8.1 Introduction

8.2 Vacuum as an Interruption Environment

8.3 Vacuum Arcs

8.3.1 Introduction

8.3.2 Cathode- and Anode Sheath

8.3.3 The Diffuse Vacuum Arc

8.3.4 The Constricted Vacuum Arc

8.3.5 Vacuum-Arc Control by Magnetic Field

References

9 Vacuum Circuit-Breakers

9.1 General Features of Vacuum Interrupters

9.2 Contact Material for Vacuum Switchgear

9.2.1 Pure Metals

9.2.2 Alloys

9.3 Reliability of Vacuum Switchgear

9.4 Electrical Lifetime

9.5 Mechanical Lifetime

9.6 Breaking Capacity

9.7 Dielectric Withstand Capability

9.8 Current Conduction

9.9 Vacuum Quality

9.10 Vacuum Switchgear for HV Systems

9.10.1 Introduction

9.10.2 Development of HV Vacuum Circuit-Breakers

9.10.3 Actual Application of HV Vacuum Circuit-Breakers

9.10.4 X-ray Emission

9.10.5 Comparison of HV Vacuum- and HV SF6 Circuit-Breakers

References

10 Special Switching Situations

10.1 Generator-Current Breaking

10.1.1 Introduction

10.1.2 Generator Circuit-Breakers

10.2 Delayed Current Zero in Transmission Systems

10.3 Disconnector Switching

10.3.1 Introduction

10.3.2 No-Load-Current Switching

10.3.3 Bus-Transfer Switching

10.4 Earthing

10.4.1 Earthing Switches

10.4.2 High-Speed Earthing Switches

10.5 Switching Related to Series Capacitor Banks

10.5.1 Series Capacitor-Bank Protection

10.5.2 By-Pass Switch

10.6 Switching Leading to Ferroresonance

10.7 Fault-Current Interruption Near Shunt Capacitor Banks

10.8 Switching in Ultra-High-Voltage (UHV) Systems

10.8.1 Insulation Levels

10.8.2 UHV System Characteristics Related to Switching

10.9 High-Voltage AC Cable System Characteristics

10.9.1 Background

10.9.2 Current Situation

10.10 Switching in DC Systems

10.10.1 Introduction

10.10.2 Low- and Medium Voltage DC Interruption

10.10.3 High-Voltage DC Interruption

10.11 Distributed Generation and Switching Transients

10.11.1 General Considerations

10.11.2 Out-of-Phase Conditions

10.12 Switching with Non-Mechanical Devices

10.12.1 Fault-Current Limitation

10.12.2 Fuses

10.12.3 IS Limiters

References

11 Switching Overvoltages and Their Mitigation

11.1 Overvoltages

11.2 Switching Overvoltages

11.3 Switching-Voltage Mitigation

11.3.1 Principles of Mitigation

11.3.2 Mitigation by Closing Resistors

11.3.3 Mitigation by Surge Arresters

11.3.4 Fast Insertion of Shunt Reactors

11.4 Mitigation by Controlled Switching

11.4.1 Principles of Controlled Switching

11.4.2 Controlled Opening

11.4.3 Controlled Closing

11.4.4 Staggered Pole Closing

11.4.5 Applications of Controlled Switching

11.4.6 Comparison of Various Measures

11.4.7 Influence of Metal-Oxide Surge Arresters on Circuit-Breaker TRVs

11.4.8 Functional Requirements for Circuit-Breakers

11.4.9 Reliability Aspects

11.5 Practical Values of Switching Overvoltages

11.5.1 Overhead Lines

11.5.2 Shunt Capacitor Banks and Shunt Reactors

References

12 Reliability Studies of Switchgear

12.1 CIGRE Studies on Reliability of Switchgear

12.1.1 Reliability

12.1.2 Worldwide Surveys

12.1.3 Population and Failure Statistics

12.2 Electrical and Mechanical Endurance

12.2.1 Degradation Due to Arcing

12.2.2 Electrical-Endurance Verification

12.2.3 Mechanical Endurance

12.3 CIGRE Studies on Life Management of Circuit-Breakers

12.3.1 Maintenance

12.3.2 Monitoring and Diagnostics

12.3.3 Life Management of Circuit-Breakers for Frequent Load-Switching

12.4 Substation and System Reliability Studies

References

13 Standards, Specification, and Commissioning

13.1 Standards for Fault-Current Breaking Tests

13.1.1 Background and History of the Standardized IEC TRV Description

13.1.2 IEC TRV Description

13.1.3 IEC Test-Duties

13.1.4 IEC TRV Parameters Selection and Application

13.2 IEC Standardized Tests for Capacitive-Current Switching

13.3 IEC Standardized Tests for Inductive-Load Switching

13.3.1 Shunt-Reactor Switching

13.3.2 Medium-Voltage Motor Switching

13.4 Specification and Commissioning

13.4.1 General Specifications

13.4.2 Circuit-Breaker Specification

13.4.3 Information to be given with Requests for Offers

13.4.4 Information to be provided with Submitted Offers

13.4.5 Circuit-Breaker Selection

13.4.6 Circuit-Breaker Commissioning

References

14 Testing

14.1 Introduction

14.2 High-Power Tests

14.2.1 Introduction

14.2.2 Direct Tests

14.2.3 Synthetic Tests

References

List of Abbreviations

Index

EULA