Protection of Modern Power Systems E-Book

Janaka B. Ekanayake

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 390

Veröffentlichungsjahr: 2023

Beschreibung

Protection of Modern Power Systems

Familiarize yourself with the cutting edge of power system protection technology

All electrical systems are vulnerable to faults, whether produced by damaged equipment or the cumulative breakdown of insulation. Protection from these faults is therefore an essential part of electrical engineering, and the various forms of protection that have developed constitute a central component of any course of study related to power systems. Particularly in recent decades, however, the demands of decarbonization and reduced dependency on fossil fuels have driven innovation in the field of power systems. With new systems and paradigms come new kinds of faults and new protection needs, which promise to place power systems protection once again at the forefront of research and development.

Protection of Modern Power Systems offers the first classroom-ready textbook to fully incorporate developments in renewable energy and ‘smart’ power systems into its overview of the field. It begins with a comprehensive guide to the principles of power system protection, before surveying the systems and equipment used in modern protection schemes, and finally discussing new and emerging protection paradigms. It promises to become the standard text in power system protection classrooms.

Protection of Modern Power Systems readers will also find:

• Treatment of the new faults and protection paradigms produced by the introduction of new renewable generators
• Discussion of SmartGrids—intelligently-controlled active systems designed to integrate renewable energy into the power system—and their protection needs
• Detailed exploration of Synchronized Measurement Technology and Intelligent Electronic Devices
• Accompanying website to include Solutions Manual for instructors

Protection of Modern Power Systems is an essential resource for students, researchers, and system engineers looking for a working knowledge of this critical subject.

Leseprobe

Protection of Modern Power Systems

Janaka Ekanayake

Senior Professor, University of Peradeniya, Sri Lanka and Visiting Professor, Cardiff University, UK

Vladimir Terzija

Professor, University of Newcastle, UK

Ajith Tennakoon

Senior Power Systems Engineer, Vysus Group, Australia

Athula Rajapakse

Professor, University of Manitoba, Canada

This edition first published 2023

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The right of Janaka Ekanayake, Vladimir Terzija, Ajith Tennakoon and Athula Rajapakse to be identified as the authors of this editorial material in this work has been asserted in accordance with law.

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Library of Congress Cataloging-in-Publication Data

Names: Ekanayake, Janaka, 1964- author. | Terzija, Vladimir, author. | Tennakoon, Ajith, author. | Rajapakse, Athula, author.

Title: Protection of modern power systems / Janaka Ekanayake, Vladimir Terzija, Ajith Tennakoon, Athula Rajapakse.

Description: Hokoben, NJ : Wiley, 2023. Identifiers: LCCN 2023017538 | ISBN 9781118817230 (hardback) | ISBN 9781118817216 (pdf) | ISBN 9781118817223 (epub)

Subjects: LCSH: Electric power systems–Protection.

Classification: LCC TK1005 .E355 2023 | DDC 621.31–dc23/eng/20230501

LC record available at https://lccn.loc.gov/2023017538

Cover image: © LTL Holdings (Pvt) Ltd.

Cover design by Wiley

Set in 9.5/12.5pt STIXTwoText by Integra Software Services Pvt. Ltd, Pondicherry, India

This book is dedicated to Jayasiri Karunanayake who was the inspiration for this book project.

Contents

Cover

Title Page

Copyright Page

Dedication

Preface

About the Authors

List of Abbreviations

About the Companion Website

1 Review of Principles of Protection

1.1 Introduction

1.2 Historical Development

1.3 Faults, Fault Currents, Voltages, and Protection

1.3.1 Types of Faults

1.3.2 Currents and Voltages under Fault Situations and Protection

1.4 Fault Current Contribution from Generators

1.5 Philosophy of Protection Relaying

1.5.1 Selectivity

1.5.2 Speed of Operation

1.5.3 Sensitivity

1.5.4 Reliability, Dependability, and Security

1.5.5 Primary and Backup Protection

1.5.6 Unit and Non-Unit Protection

1.6 Review Questions

1.7 Problems

2 Instrument Transformers

2.1 Introduction

2.2 Basic Principles of Operation

2.2.1 Shunt Mode

2.2.2 Series Mode

2.3 Current Transformers (CTS)

2.3.1 Steady-state Theory

2.3.2 Excitation Current

2.3.3 Excitation Characteristic

2.3.4 Terminal Marking and Polarity

2.3.5 CT Burden

2.3.6 CT Errors

2.3.7 Accuracy Classes

2.3.8 Accuracy Limit Factor

2.3.9 Rated Currents

2.4 Transient Response of CTs

2.4.1 Power System Fault Current

2.4.2 Flux Required to Transform the Primary Current

2.4.3 Transient Factor

2.4.4 Peak Transient Factor

2.4.5 Maximum Peak Transient Factor (

K

tfp,max

)

2.4.6 Transient Dimensioning Factor

K

td

for Specific Time

2.4.7 Rated Equivalent Limiting Secondary Voltage (

E

al

)

2.4.8 Primary Time Constant (TP) with Multiple Infeeds

2.4.9 Over-dimensioning Factor (

K

h

) Due Remanence

2.4.10 Duty Cycle

2.4.11 Auto-reclosing

2.4.12 Errors

2.4.13 CT Classes for Transient Performance

2.5 Selection of a CT

2.5.1 Rated Primary Current

2.5.2 Rated Secondary Current

2.5.3 Class, Burden, and ALF of the CTs

2.6 Voltage Transformers

2.6.1 Inductive Voltage Transformers

2.6.2 Inductive Voltage Transformer Errors

2.6.3 Inductive Voltage Transformer Classes

2.6.4 Inductive Voltage Transformer Selection

2.6.5 Terminal Marking

2.6.6 Inductive Voltage Transformer Transient Behaviour

2.6.7 Voltage Transformer Connections

2.7 Capacitor Voltage Transformer

2.7.1 Capacitive Voltage Transformer Errors

2.7.2 Capacitive Voltage Transformer Classes

2.7.3 Transient Behaviour

2.8 Non-Conventional Current and Voltage Transformers

2.8.1 Introduction

2.8.2 Non-Conventional CTs

2.8.3 Optical Voltage Transformers

2.9 Review Questions

2.10 Problems

3 Review of Principles of Protection

3.1 Introduction

3.2 Excess Current Protection

3.2.1 Discrimination by Current

3.2.2 Discrimination by Time

3.2.3 Discrimination by Time and Current

3.2.4 Inverse Characteristics

3.2.5 Grading of Relays

3.2.6 Co-ordination with Fuses

3.2.7 Plug Setting and Plug Setting Multiplier

3.2.8 Time Multiplier Setting

3.2.9 Discrimination When There Is a Delta-star Transformer

3.2.10 Earth Fault Protection

3.2.11 Directional Relaying

3.3 Differential Protection

3.3.1 Transformer Differential Protection

3.3.2 Protection Against Inter Turn Faults and Earth Faults

3.3.3 Feeder Differential Protection

3.4 Distance Protection

3.4.1 General Principles

3.4.2 Zones

3.4.3 Characteristic Presentation

3.4.4 Distance Relay Inputs for Three-Phase Faults and Phase-to-Phase Faults

3.4.5 Relationship Between Relay Voltage and ZS / ZL Ratio

3.4.6 Distance Measurement

3.4.7 Distance Relay Tele-protection Schemes

3.5 Overload Protection

3.5.1 Overhead Lines

3.5.2 Transformers

3.5.3 Generators

3.6 Load Shedding

3.7 Over-Flux Protection

3.8 Review Questions

3.9 Problems

4 Protection of Distributed Generation

4.1 Introduction

4.2 Fault Current Contribution from Different Generators

4.2.1 Synchronous Generators

4.2.2 Single-fed Induction Generators

4.2.3 Doubly-fed Induction Generators

4.2.4 Full Power Converter Generators

4.3 Protection of Distributed Generation

4.3.1 Protection of Faults within a DG

4.3.2 Protection Requirements for DGs Connected to a Distribution Network

4.3.3 Distribution System Earth Fault Protection

4.3.4 Mains Failure Protection

4.4 Effect of DG on Distribution Network Protection

4.4.1 Blinding of Protection

4.4.2 False Tripping

4.4.3 Issues with Recloser Operations

4.4.4 Impact on Distance Protection

4.5 Review Questions

4.6 Problems

5 Protection of Wind Farms

5.1 Introduction

5.2 Wind Turbine Configurations

5.2.1 Fixed Speed Wind Turbines

5.2.2 Doubly Fed Induction Generator Wind Turbines

5.2.3 Fully Rated Wind Turbines

5.3 Wind Turbine Fault Protection

5.4 Protection of On-shore Wind Farms

5.4.1 Protection Associated with Grid Interface

5.4.2 Protection Associated with Collector Network

5.4.3 Lightning and Surge Protection for Wind Farms

5.5 Protection of Offshore Wind Farms

5.5.1 Protection of LCC-HVDC

5.5.2 Protection of VSC-HVDC

5.6 Review Questions

5.7 Problems

6 Protection of PV Plants

6.1 Introduction

6.2 Components of a Solar PV Plant

6.2.1 PV Cells, Modules, or Arrays

6.2.2 Power Conversion and Conditioning Equipment

6.2.3 Controller

6.3 Protection of Rooftop Solar PV Systems

6.4 Protection of Ground Mounted Solar PV Systems

6.5 Review Questions

6.6 Problems

7 Signal Acquisition and Processing for Intelligent Electronic Devices

7.1 Introduction

7.2 Signal Parameters for an Intelligent Electronic Device

7.2.1 Signals under Normal and Abnormal Conditions

7.2.2 Spectral Content of CT/VT Measurements

7.3 Nyquist Sampling Theorem and Aliasing

7.4 A to D Conversion

7.4.1 Sampling

7.4.2 Quantisation and Encoding

7.4.3 Issues with A to D

7.4.4 A to D Conversion Techniques: Successive Approximation Method

7.5 Discrete-Time Signal Analysis

7.5.1 Discrete Fourier Transform

7.6 Sine and Cosine Filter

7.7 Review Questions

7.8 Problems

8 Numerical Relays

8.1 Introduction

8.2 Components of a Numerical Relay

8.2.1 I/V Converter

8.2.2 Anti-aliasing Filter

8.2.3 Sample and Hold Circuit, Multiplexer, and A to D Converter (ADC)

8.2.4 Microprocessor

8.3 Numerical Overcurrent Relay

8.4 Numerical Distance Relay

8.5 Numerical Differential Protection

8.6 Review Questions

8.7 Problems

9 Substation Automation and IEC 61850

9.1 Introduction

9.2 Substation Automation

9.2.1 Input/Output Devices

9.2.2 Relaying and Controlling Equipment

9.2.3 Remote Terminal Units

9.2.4 Station Computer

9.2.5 Human-machine Interface

9.2.6 Supervisory Control and Data Acquisition System

9.3 Communication between Substation Equipment

9.3.1 Physical Media for Communication

9.3.2 Serial Communication

9.4 Connection of Substation Equipment

9.5 IEC 61850

9.5.1 The IEC 61850 Data Model

9.5.2 Time-critical Information Exchange

9.5.3 Sampled Values

9.5.4 SA Design

9.6 Review Questions

9.7 Problems

10 Wide Area Monitoring, Protection, and Control Fundamentals

10.1 System Needs for Wide Area Monitoring, Protection, and Control

10.2 Synchronised Measurement Technology

10.2.1 Definition of Synchrophasors

10.2.2 Synchrophasor Measurement Errors

10.2.3 Timing Sources

10.2.4 Phasor Measurement Unit

10.2.5 PMU Measurement Latency

10.2.6 Phasor Data Concentrators

10.2.7 Communication Infrastructure

10.2.8 Architecture of Synchrophasor Measurement Systems

10.2.9 Communication Networks for WAMPAC System

10.3 Wide Area Monitoring, Protection, and Control Applications

10.3.1 Post-disturbance Analysis and Model Validation

10.3.2 Characterisation of Load Centres

10.3.3 Monitoring of Parameters of Synchronous Generators

10.3.4 PMU-based State Estimation

10.3.5 PMU-based Monitoring of Inter-area Oscillations

10.3.6 PMU-based Coordinated Power Oscillations Damping

10.3.7 PMU-based Adaptive Underfrequency Load-shedding and Smart Frequency Control

10.3.8 Adaptive PMU Based Fault Location Method

10.3.9 Transmission Line Fault Location Based on Time Synchronised Samples

10.4 Practical WAMPAC Examples and Installations

10.4.1 Future Intelligent Transmission Network Substation (FITNESS) Project

10.4.2 Visualisation of Real Time System Dynamics Using Enhanced Monitoring (VISOR) Project

10.4.3 The Enhanced Frequency Control Capability (EFCC) Project

10.5 Review Questions

Index

End User License Agreement

List of Tables

CHAPTER 01

Table 1.1 Fault currents for different faults.

Table 1.2 Voltages under different faults.

CHAPTER 02

Table 2.1 Short circuit current variations...

Table 2.2 CT classes.

Table 2.3 Measuring voltage transformer accuracy limits.

Table 2.4 Protective voltage transformer accuracy limits.

Table 2.5 Voltage factor.

Table 2.6 Measuring voltage transformer accuracy limits.

Table 2.7 Protective voltage transformer accuracy limits.

Table 2.8 Voltage factor.

CHAPTER 03

Table.3.1 Current setting of each relay.

Table 3.2 Discrimination by time.

Table 3.3 Typical relay timing errors and final...

Table 3.4 Thermal relay characteristic.

Table 3.5 300A Fuse characteristic.

Table 3.6 Final relay settings.

CHAPTER 04

Table 4.1 Categorisation of power generating units under G99.

Table 4.2 Under and over frequency relay settings.

Table 4.3 Under and overvoltage relay settings.

CHAPTER 05

Table 5.1 Grading margin when considering the...

CHAPTER 06

Table 6.1 SPD requirement [3].

Table 6.2 Protection setting [4].

CHAPTER 07

Table 7.1 Converting 2.9 V to its digital...

Table 7.2 Calculation of the fundamental phasor.

Table 7.3 Weights of the 2nd, 3rd and 4th harmonics.

Table 7.4 Sampled value.

Table 7.5 Sampled value.

CHAPTER 08

Table 8.1 Impedances considered in the fault loop.

Table 8.2 Harmonics presence in the factory.

CHAPTER 09

Table 9.1 Different signals feeding into...

Table 9.2 Different functions of SCADA.

Table 9.3 Comparison of two MODBUS implementations.

Table 9.4 Description of logical nodes.

CHAPTER 10

Table 10.1 PDC functions.

List of Illustrations

CHAPTER 01

Figure 1.1 Figure for problem 1.

Figure 1.2 Figure for problem 2.

CHAPTER 02

Figure 2.1 CT and its equivalent circuit.

Figure 2.2 Phasor diagram.

Figure 2.3 Variation of CT errors.

Figure 2.4 Excitation characteristic.

Figure 2.5 Terminal marking of CTs.

Figure 2.6 Equivalent circuit – ring CT.

Figure 2.7 CT flux due to the short circuit current.

Figure 2.8 The variation of...

Figure 2.9 CT flux during unsuccessful auto-reclosing.

Figure 2.10 Equivalent circuit and vector diagram for a VT.

Figure 2.11 Voltage transformer terminal marking.

Figure 2.12 Broken-delta connection.

Figure 2.13 Open delta connection.

Figure 2.14 (a) Capacitive voltage transformer...

Figure 2.15 Rogowski coil [8, 9].

Figure 2.16 Magnetising characteristic and...

Figure 2.17 Operating limits of a Rogowski coil.

Figure 2.18 Current transient.

Figure 2.19 A part of a distribution circuit.

Figure 2.20 Optical CT.

Figure 2.21 Network diagram.

CHAPTER 03

Figure 3.1 Network for Example 3.1.

Figure 3.2 Overcurrent protection for a transformer.

Figure 3.3 Relay operational characteristics...

Figure 3.4 Discriminative protection with IDMT relays.

Figure 3.5 IDMT characteristics (IEC).

Figure 3.6 Currents on star and delta sides...

Figure 3.7 Grading margin determination for...

Figure 3.8 Typical distribution networks.

Figure 3.9 Earth fault protection [2].

Figure 3.10 Double circuit line with...

Figure 3.11 Directional earth fault protection.

Figure 3.12 Principle of differential protection.

Figure 3.13 Bias differential characteristic.

Figure 3.14 A single phase to earth fault on the...

Figure 3.15 Fault current variation.

Figure 3.16 Principle of high impedance...

Figure 3.17 Restricted earth fault protection.

Figure 3.18 Differential principle applied to...

Figure 3.19 Current balance and voltage...

Figure 3.20 CT requirements with and without...

Figure 3.21 Two relay arrangement for feeder...

Figure 3.22 Summation transformer.

Figure 3.23 General principles of...

Figure 3.24 Zones of distance protection.

Figure 3.25 Impedance relay characteristics.

Figure 3.26 Current inputs of a distance...

Figure 3.27 Direct under-reach transfer...

Figure 3.28 Permissive under-reach transfer...

Figure 3.29 Permissive over-reach transfer...

Figure 3.30 Blocking scheme.

Figure 3.31 Time-frequency characteristics...

Figure 3.32 The settings for different stages.

Figure 3.33 Over-flux of a transformer.

Figure 3.34 Figure for Problem 1.

Figure 3.35 Figure for Problem 2.

Figure 3.36 Figure for Problem 3.

Figure 3.37 Figure for Problem 8.

Figure 3.38 Figure for Problem 9.

CHAPTER 04

Figure 4.1 Fault current contribution...

Figure 4.2 Fault current contribution...

Figure 4.3 Typical configuration of a DFIG.

Figure 4.4 DG with full power converter.

Figure 4.5 Differential protection of generator.

Figure 4.6 Typical protection requirement...

Figure 4.7 Operating characteristics...

Figure 4.8 Earth fault protection for DG...

Figure 4.9 Typical distribution network with a DG.

Figure 4.10 Equivalent circuit of the...

Figure 4.11 Network for Example 4.2.

Figure 4.12 Typical network with a DG.

Figure 4.13 Network for Example 4.3.

Figure 4.14 A typical distribution feeder with recloser.

Figure 4.15 A typical distribution feeder...

Figure 4.16 Fuse (thick) and recloser (thin)...

Figure 4.17 Circuit for Example 4.4.

Figure 4.18 Operating characteristics of...

Figure 4.19 Circuit to show the effect on distance relay.

Figure 4.20 Figure for problem 2.

Figure 4.21 Figure for problem 4.

Figure 4.22 Figure for problem 5.

CHAPTER 05

Figure 5.1 FSIG-based wind turbine.

Figure 5.2 Doubly fed wind turbine.

Figure 5.3 FPC based wind turbine.

Figure 5.4 Active crowbar circuit for FRT.

Figure 5.5 Chopper circuit.

Figure 5.6 Operation of the chopper.

Figure 5.7 Variation of generator and...

Figure 5.8 Typical wind farm arrangement.

Figure 5.9 Wind farm connected to a 33 kV network.

Figure 5.10 Wind farm connected to 132 kV network.

Figure 5.11 Collector network with underground cables.

Figure 5.12 Network for Example 5.3.

Figure 5.13 Relay characteristics...

Figure 5.14 Wind turbine earthing arrangement.

Figure 5.15 Surge protection of wind turbines.

Figure 5.16 Typical connection configurations...

Figure 5.17 Protection schemes used for dc...

Figure 5.18 Protection schemes used for dc...

Figure 5.19 A VSC with a dc circuit fault.

Figure 5.20 The dc link current and voltage...

Figure 5.21 Multi-terminal VSC HVDC scheme.

Figure 5.22 Network for Problem 5.

CHAPTER 06

Figure 6.1 Cross section of a PV cell.

Figure 6.2 Typical elements of a PV system.

Figure 6.3 Blocking and bypass diodes.

Figure 6.4 Boost converter for MPPT.

Figure 6.5 P-V characteristic of the PV module.

Figure 6.6 A single-phase inverter.

Figure 6.7 Typical components...

Figure 6.8 Configuration with string...

Figure 6.9 Configuration with string groups...

Figure 6.10 Configuration with sub arrays.

Figure 6.11 A large PV system.

Figure 6.12 A large PV system.

Figure 6.13 Fuse characteristic.

Figure 6.14 Ground fault currents.

CHAPTER 07

Figure 7.1 Time domain and frequency domain...

Figure 7.2 Effect of sampling in the frequency domain.

Figure 7.3 Effects of under-sampling of a 50 Hz signal.

Figure 7.4 The generation of spurious frequencies...

Figure 7.5 Representation...

Figure 7.6 Analogue to Digital conversion process.

Figure 7.7 Variation of the quantisation error...

Figure 7.8 Quantisation noise spectrum for sampling frequencies.

Figure 7.9 Nonlinearity errors in an ADC.

Figure 7.10 Comparator.

Figure 7.11 Operation of a 3-bit successive...

Figure 7.12 A 50 Hz signal containing third...

Figure 7.13 Frequency response of cosine and sine filters.

Figure 7.14 Frequency response of cosine...

CHAPTER 08

Figure 8.1 Components of a numerical relay.

Figure 8.2 Op-Amp current to voltage converter.

Figure 8.3 An anti-aliasing filter.

Figure 8.4 Characteristic of a passive low pass filter.

Figure 8.5 Characteristic of an active low pass filter.

Figure 8.6 Synchronous sampling.

Figure 8.7 Signal flow in the microprocessor section.

Figure 8.8 Flowchart of an overcurrent relay.

Figure 8.9 Phase comparison type MHO relay.

Figure 8.10 Equivalent circuit for the impedance seen by the relay.

Figure 8.11 Polarisation voltage.

Figure 8.12 Typical numerical distance...

Figure 8.13 Relay characteristics.

Figure 8.14 Bias differential relay.

Figure 8.15 Differential protection...

Figure 8.16 Filter circuit.

CHAPTER 09

Figure 9.1 Typical SA architecture.

Figure 9.2 Typical display of an HMI.

Figure 9.3 Typical SCADA/EMS interfaces.

Figure 9.4 EIA485 multi-drop network.

Figure 9.5 Star and ring connection.

Figure 9.6 MODBUS protocol stack.

Figure 9.7 Typical wired connection inside a substation.

Figure 9.8 Introduction of the process bus.

Figure 9.9 Connection within a substation.

Figure 9.10 Connection within a substation.

Figure 9.11 Redundancy provided in the star topology.

Figure 9.12 IEC 61850 data structure.

Figure 9.13 Logical devices.

Figure 9.14 Data and attributes associated with LN PDIS.

Figure 9.15 Connection between PDIS, PTRC, RREC...

Figure 9.16 GOOSE mapping to TCP/IP protocol architecture.

Figure 9.17 Fast bus trip scheme.

Figure 9.18 GOOSE message flows.

Figure 9.19 Merging unit.

Figure 9.20 SV mapping to TCP/IP protocol architecture.

Figure 9.21 SA design process.

CHAPTER 10

Figure 10.1 Synchrophasor representation...

Figure 10.2 Relationship between actual...

Figure 10.3 Model of a typical PMU with DFT...

Figure 10.4 Latency in PMU measurements.

Figure 10.5 Typical architecture of a wide...

Figure 10.6 Combination of different communication...

Figure 10.7 Sequence of cascading events...

Figure 10.8 Information about the number...

Figure 10.9 Block diagram of the model validation.

Figure 10.10 Typical exponential recovery...

Figure 10.11 A global block diagram of the estimation process.

Figure 10.12 Estimated and measured active...

Figure 10.13 Estimated and measured active...

Figure 10.14 Estimation of the field winding resistance, rFD.

Figure 10.15 Estimation of the magnetising...

Figure 10.16 Building block of a state estimator [43].

Figure 10.17 State estimator with time...

Figure 10.18 Two options for including...

Figure 10.19 IEEE 14 bus test system with 3 PMUs.

Figure 10.20 General structure of the discrete DSE.

Figure 10.21 Performance index J (p.u.) under bad data...

Figure 10.22 PMU locations in the GB grid.

Figure 10.23 PMU measured angular difference between...

Figure 10.24 Damping ratio, characterising inter-area...

Figure 10.25 LQGC-based centralised power system...

Figure 10.26 Four generator test system performing...

Figure 10.27 LQGC-based centralised wide area...

Figure 10.28 Generators’ rotor speed...

Figure 10.29 Frequencies in four cases...

Figure 10.30 The long line representation...

Figure 10.31 Single line diagram of PMU...

Figure 10.32 R-phase fault current magnitude...

Figure 10.33 Sample synchronisation,...

Figure 10.35 Equivalent diagram of a single...

Figure 10.34 Faulty overhead transmission line...

Figure 10.36 Line voltages at terminals A and B.

Figure 10.37 Line currents at terminals A and B.

Figure 10.38 Estimated fault distance from terminal A.

Figure 10.39 Digital substation architecture [55].

Figure 10.40 Digital substation roles...

Figure 10.41 Elements of VISOR WAMS [53].

Figure 10.42 Overview of GB WAMS architecture...

Figure 10.43 Linear state estimator supporting...

Figure 10.44 GB system frequency and its rate of...

Figure 10.45 The principle of the smart...

Guide

Cover

Title Page

Copyright Page

Dedication

Table of Contents

Preface

About the Authors

List of Abbreviations

About the Companion Website

Begin Reading

Index

End User License Agreement

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Preface

At the end of the 19th century, mainly fuses were used in direct current systems to protect generators, cables, motors, and consumer loads from overload or short-circuit currents. The invention of current transformers in 1898 made it possible to connect secondary relays to trigger oil circuit breakers. Around 1903 electromechanical relays were produced, which were mainly used to switch off generators. Semiconductor technology was initially used in selective protection technology in 1937 by utilizing diodes in bridge configuration as impedance measuring elements. However, solid-state relays that utilize diodes, transistors, and operational amplifiers were commercially available in the late 1950s and they offered greater flexibility than electromechanical relays. Modern protection relays appear as early as 1971 and today they have captured all the new installations and substation upgrades.

Even though there are many books discussing protection principles and applications, they lack comprehensive treatment of modern protection components and practices. Further, the recent trends in decarbonizing the power sector and embedding information and communication technologies in power system equipment and operations have created new impediments and enablers in power system protection. Even though these are now discussed in advanced power system modules in many universities in the world, the textbooks available for these courses are limited and the treatment of modern protection equipment, systems, and paradigms are briefed. Having recognized these gaps, the proposed book is structured to first provide a comprehensive guide to protection principles, then move into digital systems and equipment used for modern protection schemes, and finally discuss the new protection paradigms that are emerging due to the application of Synchronized Measurement Technology, involving Phasor Measurement Units, Data Concentrators, and new Wide Area Monitoring, Protection and Control (WAMPAC) applications.

The book provides a detailed treatment of protection principles supported by worked examples, review questions, and problems so it can be used as a course textbook. Further, it discusses the issues and new paradigms in protection that resulted from the addition of a new form of generators to the power system, such as wind, PV, and other distributed generation. As the industry trend is migrating to more and more digital protection equipment, the book provides comprehensive treatment to Intelligent Electronic Devices, their applications, and communication requirements. Finally, a detailed discussion of the application of Phasor Measurement Units to the power system, particularly wide area approaches (WAMPAC), is provided.

About the Authors

Janaka Ekanayake – Janaka Bandara Ekanayake is the Senior Professor and Chair of Electrical and Electronic Engineering of the University of Peradeniya, Sri Lanka. He is a Visiting Professor at the Institute of Energy at Cardiff University, UK, and an Honorary Professor of the School of Electrical, Computer and Telecommunication Engineering, University of Wollongong, Australia. He has published more than 100 papers in refereed journals, and more than 100 papers in conferences and has also co-authored 7 books. The key books to which he contributed are Renewable Energy Engineering (2017), Cambridge University Press; Smart Electricity Distribution Networks (2017), CRC Press; Electric Power Systems (2012), Wiley; Smart Grid: Technology and Applications (2012), Wiley; Distributed Generation (2010), Institution of Engineering and Technology; and Wind Energy Generation: Modelling and Control (2009) Wiley. He is a member of the Advisory Board of IET journal of Renewable Power Generation, a member of the Editorial Board of Springer Nature scientific reports, Green Technology, Resilience, and Sustainability, and Wind Engineering journal.

Vladimir Terzija – Vladimir Terzija is a Professor at Newcastle University, UK. Prior to that he was a Full Professor and the Head of Laboratory of Modern Energy Systems at Skoltech, Moscow, Russian Federation. He received the Dipl.-Ing., M.Sc., and Ph.D. degrees in Electrical Engineering from the University of Belgrade, Belgrade, Serbia, in 1988, 1993, and 1997, respectively. In the period 2006-2020 he was the EPSRC Chair Professor in Power System Engineering with the Department of Electrical and Electronic Engineering, University of Manchester, Manchester, UK. From 1997 to 1999, he was an Assistant Professor with the University of Belgrade, Belgrade, Serbia. From 2000 to 2006, he was a Senior Specialist for switchgear and distribution automation with ABB Calor Emag, Ratingen, Germany. His research interests include smart grid applications, wide-area monitoring, protection and control, multi-energy systems, switchgear and transient processes, as well as data science applications in power systems. He has contributed to a number of IEEE and Cigre working groups related to power system protection and control in various capacities. Professor Terzija is the Editor-in-Chief for the International Journal of Electrical Power and Energy Systems, Alexander von Humboldt Fellow, IEEE Fellow and recipient of the National Friendship Award, China and Distinguished Professor with Shandong University, Jinan, China.

Ajith Tennakoon – Ajith Tennakoon is a professional engineer currently working as a Senior Power Systems Engineer for Vysus Group, Australia, involved in grid connection studies for renewable energy sources mainly within Australia. He has extensive experience in Power System protection and has been heading the Transmission Network protection in Sri Lanka. Previously he was a Senior Protection Engineer and engaged in design and implementation of Generator protection systems in Sri Lanka.

Athula Rajapakse – Athula Rajapakse is a Professor at the Department of Electrical and Computer Engineering of the University of Manitoba, Canada. He earned the B.Sc. (Eng.) degree from the University of Moratuwa, Sri Lanka in 1990, the M.Eng. degree from the Asian Institute of Technology, Thailand in 1993, and the Ph.D. degree from The University of Tokyo, Japan in 1998. He leads the Intelligent Power Grid Laboratory at the University of Manitoba and has conducted wide range of research related to power system protection, wide area protection and control, protection of future HVDC grids, and grid integration of renewable energy. He has contributed to several IEEE and CIGRE working groups related to power system protection in various capacities.

Additional Contributors to the Book

Roshan Godaliyadda – Roshan Indika Godaliyadda is a Professor at the Department of Electrical and Electronic Engineering, University of Peradeniya. He obtained his BSc Eng. degree in Electrical and Electronic Engineering from University of Peradeniya, Sri Lanka, and PhD from the Electrical and Computer Engineering Department, National University of Singapore. He is a senior member of the IEEE. His research work spans the areas of Signal and Image Processing, Artificial Intelligence and Computer Vision, Remote Sensing, Spectral Imaging and the Smart Grid. He has numerous publications in leading journals and conferences such as: IEEE Transactions on Remote Sensing and Geoscience, Applied Energy, IEEE Transactions on Smart Grid, Journal of Food Engineering, International Journal of Electrical Power and Energy Systems, IEEE Transactions on Measurement and Instrumentation, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, PLoSONE, Sensors, IEEE Access, ICIP, WCNC and IGARSS to name a few.

Parakrama Ekanayake – Mervyn Parakrama B. Ekanayake is a Professor at the Department of Electrical and Electronic Engineering, University of Peradeniya. He obtained his baccalaureate degree in Electrical and Electronic Engineering from the University of Peradeniya, Sri Lanka, and his doctoral degree from the Department of Mathematics and Statistics, Texas Tech University, USA. He is a Senior Member of the IEEE. His current research interests include applications of signal and image processing, systems theory, and artificial intelligence to problems in machine vision, smart grid, remote sensing, and biomedical signal processing. He has more than one hundred publications in leading conferences and journals.

List of Abbreviations

ac

Alternative current

ADC

Analog to digital converter

CB

Circuit breaker

CT

Current Transformer

dc

Direct current

DG

Distributed Generation

DER

Distributed energy resources

DFIG

Doubly-fed Induction generators

DFT

Discrete Fourier Transform

EMF

Electro-Motive Force

FRC

Full power converter

FRT

Fault Ride Through

FSIG

Fixed speed induction generator

GPS

Global Position System

HVAC

High voltage ac

HVDC

High voltage dc

IDMT

Inverse Definite Minimum Time

IEC

International Electrotechnical Commission

IED

Intelligent Electronic Device

IGBT

Insulated gate bipolar transistor

LCC

Line commutator converter

LV

Low voltage

MMF

Magneto-Motive Force

MV

Medium voltage

NVD

Neutral Voltage Displacement

PDC

Phasor data concentrators

PMU

Phasor measurement unit

PV

Photovoltaic

PWM

Pulse width modulation

RMU

Ring main unit

ROCOF

Rate of Change of Frequency

SA

Substation Automation

SCADA

Supervisory Control and Data Acquisition System

SPD

Surge protective devices

TMS

Time multiplier setting

VSC

Voltage Source Converter

VT

Voltage Transformer

WAMPAC

Wide-Area Monitoring, Protection and Control

About the Companion Website

Protection of Modern Power Systems is accompanied by a companion website:

www.wiley.com/go/ekanayake/modernpower

The website includes:

Solutions Manual

1 Review of Principles of Protection

1.1 Introduction

The power system is an interconnected network of electrical components that are designed, installed, commissioned, and operated in accordance with international/national standards to provide a reliable supply of electricity to meet a country’s electrical energy needs. Irrespective of how such components are installed, whether in the open air, underground, in-house, or even underwater, they will be subjected to vagaries of weather, undesired human action, accidents, and natural calamities. All of these, as well as the defects or abnormalities in the components themselves, can disturb the smooth operation of the power system, creating blackouts or brownouts or even causing damage to property, equipment, and human life.

Therefore, it has become mandatory to commission automatic devices that can detect such abnormal situations in the power system and prevent or clear such abnormalities discriminatively as quickly as possible to facilitate normal operation. These automatic devices are popularly known as protective relays and the selection and coordination of such relays or protective relaying have become an indispensable part of the operation of power systems.

1.2 Historical Development

Even from the very early days of the development of industrial power systems, which usually consisted of a small generator supplying a local load, the aspect of protection has been foremost in the minds of engineers.

The first protection scheme employed to protect the industrial power system was a man, the machine minder! It was his job to watch the ammeter, sniff occasionally, feel the conductors, and at the first sign of smoke, open a great knife switch on the wall, stand back, and waff out the arc with his cloth cap. However, with the continuing development of the electricity industry, the requirement for an automatic device to detect and isolate the faulty part of the power system became an urgent necessity. The first such automatic device was the fuse. These are still being used in distribution systems.

Centralised electricity generation, interconnection of power systems, and the high level of reliability demanded by the users forced the engineers to develop this branch of engineering from the primitive level of manual monitoring to unbelievable heights within a period of little more than a century.

1.3 Faults, Fault Currents, Voltages, and Protection

Faults and abnormal conditions are a common occurrence in any part of the power system, which constitutes electrical equipment based on varying operating principles, from generators, transformers, transmission lines, circuit breakers, and many others. Such abnormalities often cause very high currents to flow, liberating a large amount of heat at the point of fault and creating voltage drops in the system.

1.3.1 Types of Faults

Types of electrical faults that can befall a power system are varied and can be categorised as short circuits, open circuits, inter-turn faults, and abnormalities due to operational errors.

Short circuits can arise in any power system component due to an abnormal connection of one or more phases to one another or earth or both. Open circuits could also occur in any power system component and the most common are joint failures and improper closing or opening of a circuit breaker or isolator legs. Inter-turn faults or short circuits between adjacent turns of the same windings of a phase are common in transformers and generators. Human or operational errors could occur when operating the power system due to erroneous operations carried out by operational staff, which may result in short circuits, open circuits, or power quality issues.

1.3.2 Currents and Voltages under Fault Situations and Protection

All electrical faults involving short circuits or open circuits can be primarily divided into two categories; namely, balanced or symmetrical faults and unbalanced or unsymmetrical faults. Symmetrical components have to be used to analyse the latter. Such currents and voltages are the only information extracted from the power system for the protection relays to perform their duty of detecting faulty parts and isolating the same discriminatively.

The most severe fault in a power system is the short circuit; this can be three-phase, phase-to-phase, or one or more phases involving the ground. In these situations, the Electro-Motive Force (EMF) is shorted by the impedances of the power system components up to the fault, and the resulting fault current will depend on

Type of fault: three-phase, phase-to-phase, single-phase

Position of the fault, as to how far down the system

Neutral earthing

Generation connected and the internal EMFs of the machines

Power system configuration

Fault currents and voltages under different fault conditions are given in Tables 1.1 and 1.2 respectively [1]. In the table Z1, Z2, and Z3 are positive, negative, and zero sequence impedances of the network, calculated from a single equivalent source having EMF E to the faulty point.

Table 1.1 Fault currents for different faults.

Fault

Phase sequence components

Phase current values

I

1

I

2

I

3

I

a

I

b

I

c

Three-phase

0

0

Phase-to-phase

0

0

Single-phase to earth

0

0

Two phases to earth

0

Phase-to-phase + Phase-to-earth

where Ia, Ib, and Ic are phase currents and I1, I2, and I3 are positive, negative, and zero sequence components; a= -0.5+j0.866.

Table 1.2 Voltages under different faults.

Fault

Phase sequence components

Phase voltage values

V

1

V

2

V

3

V

a

V

b

V

c

Three-phase

0

0

0

0

0

0

Phase-to-phase

0

Single-phase to earth

0

Two phases to earth

0

0

Phase-to-phase + Phase-to-earth

0

where Va, Vb, and Vc are phase currents and V1, V2, and V3 are positive, negative, and zero sequence components

1.4 Fault Current Contribution from Generators

A protection engineer should be aware of the fault current contributions from the different types of generators. A few decades ago, power systems were fed mainly with synchronous generators, but today the situation is vastly different, with other types of generators becoming important contributors to generation. A detailed analysis of the fault current contributions from generators that are employed in conventional plants and distributed generation plants is given in Chapter 4.

1.5 Philosophy of Protection Relaying

The primary objective of a protection relaying system is to detect faulty power system components or abnormal situations prevailing in a power system and to initiate action to isolate the appropriate system elements. This is applicable for all parts of the power system whether it is generation, transmission, or distribution. In order to fulfil this primary objective, protection philosophy shall be defined to achieve the following:

Ensuring continuity of electricity supply.

Facilitating normal operation by maintaining dynamic and steady state stability.

Preventing or mitigating equipment damage.

Minimising equipment outage times.

Minimising system outage times.

Minimising the extent of areas affected by outages.

Providing data related to the faulty item/abnormal operation.

A protective relaying system alone cannot accomplish this in isolation, but it should have the ability to fulfil these in association with the other features incorporated in a power system. Basic general requirements of such a protective relaying system are as follows:

1.5.1 Selectivity

A protective relaying system has the ability to isolate only the faulty section of the circuit after the occurrence of a short circuit; this feature is known as selectivity or discrimination.

1.5.2 Speed of Operation

Fault clearing time of a protective relaying system should be kept to a minimum to minimise the damage to the equipment, maintain the power system stability, and also to maintain the normal operation of the system.

1.5.3 Sensitivity

A protective relaying system should be capable of responding to abnormalities of the power system even under minimum fault conditions and should feature a definite sensitivity, which is defined as the minutest abnormality it can respond to.

1.5.4 Reliability, Dependability, and Security

A protection relaying system should initiate tripping when required, and the ability to do so is the measure of its reliability. There are two ways in which a relaying system can be unreliable. They may fail to operate when they should operate, and they may operate when they are not expected to operate.

The dependability is the ability of the protection scheme to operate correctly when required, and security is the ability to avoid unnecessary operations. Abnormalities in certain power system components can be rare, but the relaying system must continuously be on the alert over long intervals so that it can respond to abnormalities at any moment, in accordance with the design, when occasion demands.

1.5.5 Primary and Backup Protection

Protection relays are also liable to failure and hence a “backup” is considered mandatory. Accordingly, all protection relaying systems should comprise a primary relaying system and a backup relaying system. This will ensure that all faults in the system are cleared. Backup protection can be a local backup or remote backup.

1.5.6 Unit and Non-Unit Protection

Protection systems can be either unit or non-unit. Unit protection responds to faults in the protection zone alone, and it does not respond to through faults. Non-unit systems do not have specified zone boundaries. Differential relay is a unit protection system, whereas over current relay is a non-unit system. Distance relay is a non-unit protection system, but it can be converted into unit protection using communication channels.

1.6 Review Questions

Why are protection systems required for power systems?

How do short circuits or abnormal operations affect power systems?

What is the first automatic protection device? Explain where these are used now.

What are the main functions of protective relays and those of circuit breakers?

Explain the general characteristics/features that define the quality of protective relaying.

What are primary protection, backup protection, local backup protection, and remote backup protection?

Define unit protection and non-unit protection.

Give examples for unit protection and non-unit protection schemes.

1.7 Problems

For the circuit shown in

Figure 1.1

, considering the mal-operation of relays R

2

and R

5,

describe the loss of dependability and the loss of sensitivity.

Figure 1.1 Figure for problem 1.

For the circuit shown in

Figure 1.2

, the breaker B3 did not operate for the fault shown. Which relay or relays will provide the backup protection and which relay or relays will provide primary protection?

Figure 1.2 Figure for problem 2.

The performance of an overcurrent relay was monitored over a period of one year. It was found that the relay operated 16 times and out of that 13 were correct trips. If the relay failed to issue a trip decision on 3 occasions, calculate the performance index or the percentage dependability of the protection scheme.

Reference

1

Grainger, J.J. and Stevenson, W.D. (2016).

Power System Analysis

. McGraw Hill. ISBN: 9781259008351.

2 Instrument Transformers

This chapter deals with the operation and performance of the conventional and digital instrument transformers and their selection for different types of applications. When selecting instrument transformers for a particular application, it is also necessary to consider other aspects such as mechanical construction, impulse levels, service conditions, insulation class, etc. However, these will not be addressed here, as international standards such as IEEE 242–2001 [1] and IEC61869-100 [2] on instrument transformers provide sufficient information.

2.1 Introduction