Protective Relaying

INTRODUCTION AND GENERAL PHILOSOPHIES
Introduction and Definitions
Typical Protective Relays and Relay Systems
Typical Power Circuit Breakers
Nomenclature and Device Numbers
Typical Relay and Circuit Breaker Connections
Basic Objectives of System Protection
Factors Affecting the Protection System
Classification of Relays
Protective Relay Performance
Principles of Relay Application
Information for Application
Bibliography
FUNDAMENTAL UNITS: PER UNIT AND PERCENT VALUES
Introduction
Per Unit and Percent Definitions
Advantages of Per Unit and Percent
General Relations Between Circuit Quantities
Base Quantities
Per Unit and Percent Impedance Relations
Per Unit and Percent Impedances of Transformer Units
Changing Per Unit (Percent) Quantities to Different Bases
Bibliography
PHASORS AND POLARITY
Introduction
Phasors
Circuit and Phasor Diagrams for a Balanced Three-Phase Power System
Phasor and Phase Rotation
Polarity
Application of Polarity for Phase-Fault Directional Sensing
Directional Sensing for Ground Faults: Voltage Polarization
Directional Sensing for Ground Faults: Current Polarization
Other Directional-Sensing Connections
Summary
SYMMETRICAL COMPONENTS: A REVIEW
Introduction and Background
Positive-Sequence Set
Nomenclature Convenience
Negative-Sequence Set
Zero-Sequence Set
General Equations
Sequence Independence
Positive-Sequence Sources
Sequence Networks
Shunt Unbalance Sequence Network Interconnections
Example: Fault Calculations on a Typical System Shown in Figure 4.16
Example: Fault Calculation for Autotransformers
Example: Open-Phase Conductor
Example: Open Phase Falling to Ground on One Side
Series and Simultaneous Unbalances
Overview
Summary
Bibliography
Appendix 4.1: Short-Circuit MVA and Equivalent Impedance
Appendix 4.2: Impedance and Sequence Connections for Transformer Banks
Appendix 4.3: Sequence Phase Shifts Through Wye-Delta Transformer Banks
RELAY INPUT SOURCES
Introduction
Equivalent Circuits of Current and Voltage Transformers
Current Transformers for Protection Applications
Current Transformer Performance on a Symmetrical AC Component
Secondary Burdens During Faults
CT Selection and Performance Evaluation for Phase Faults
Performance Evaluation for Ground Relays
Effect of Unenergized CTs on Performance
Flux Summation Current Transformer
Current Transformer Performance on the DC Component
Summary: Current Transformer Performance Evaluation
Current Transformer Residual Flux and Subsidence Transients
Auxiliary Current Transformers in CT Secondary Circuits
Voltage Transformers for Protective Applications
Bibliography
PROTECTION FUNDAMENTALS AND BASIC DESIGN PRINCIPLES
Introduction
The Differential Principle
Overcurrent-Distance Protection and the Basic Protection Problem
Backup Protection: Remote Versus Local
Basic Design Principles
Ground Distance Relays
Solid-State Microprocessor Relays
Summary
Bibliography
SYSTEM-GROUNDING PRINCIPLES
Introduction
Ungrounded Systems
Transient Overvoltages
Ground-Detection Methods for Ungrounded Systems
High-Impedance-Grounding Systems
System Grounding for Mine or Other Hazardous-Type Applications
Low-Impedance Grounding
Solid (Effective) Grounding
Ferroresonance in Three-Phase Power Systems
Safety Grounding
Grounding Summary and Recommendations
Bibliography
GENERATOR PROTECTION: UTILITY AND NONUTILITY OWNED
Introduction and Potential Problems
Generator Connections and Typical Protection
Stator Phase-Fault Protection for All Size Generators
Unit Transformer Phase-Fault Differential Protection (87TG)
Phase-Fault Backup Protection (51V) or (21)
Negative-Sequence Current Backup Protection
Stator Ground-Fault Protection
Multiple Generator Units Connected Directly to a Transformer: Grounding and Protection
Field Ground Protection (64)
Generator Off-Line Protection
Reduced of Lost Excitation Protection (40)
Generator Protection for System Disturbances and Operational Hazards
Synchronous Condenser Protection
Generator-Tripping Systems
Station Auxiliary Service System
Protection Summary
Bibliography
TRANSFORMER, REACTOR, AND SHUNT CAPACITOR PROTECTION
Transformers
Factors Affecting Differential Protection
Magnetizing Inrush
Transformer Differential Relay Characteristics
Application and Connection of Transformer Differential Relays
Example: Differential Protection Connections for a Two-Winding Wye-Delta Transformer Bank
Load Tap-Changing Transformers
Example: Differential Protection Connections for Multiwinding Transformer Bank
Application of Auxiliaries for Current Balancing
Paralleling CTs in Differential Circuits
Special Connections for Transformer Differential Relays
Differential Protection for Three-Phase Banks of Single-Phase Transformer Units
Ground (Zero-Sequence) Differential Protection for Transformers
Equipment for Transfer Trip Systems
Mechanical Fault Detection for Transformers
Grounding Transformer Protection
Ground Differential Protection with Directional Relays
Protection of Regulating Transformers
Transformer Overcurrent Protection
Transformer Overload-Through-Fault-Withstand Standards
Examples: Transformer Overcurrent Protection
Transformer Thermal Protection
Overvoltage on Transformers
Summary: Typical Protection for Transformers
Reactors
Capacitors
Bibliography
BUS PROTECTION
Introduction: Typical Bus Arrangements
Single Breaker-Single Bus
Single Buses Connected with Bus Tie
Main and Transfer Buses with Single Breaker
Single Breaker-Double Bus
Double Breaker-Double Bus
Ring Bus
Breaker-and-a-Half Bus
Transformer-Bus Combination
General Summary of Buses
Differential Protection for Buses
Other Bus Differential Systems
Ground-Fault Bus
Protection Summary
Bibliography
MOTOR PROTECTION
Introduction
Potential Motor Hazards
Motor Characteristics Involved in Protection
Induction Motor Equivalent Circuit
General Motor Protection
Phase-Fault Protection
Differential Protection
Ground-Fault Protection
Thermal and Locked-Rotor Protection
Locked-Rotor Protection for Large Motors
System Unbalance and Motors
Unbalance and Phase Rotation Protection
Undervoltage Protection
Bus Transfer and Reclosing
Repetitive Starts and Jogging Protection
Multifunction Microprocessor Motor Protection Units
Synchronous Motor Protection
Summary: Typical Protection for Motors
Bibliography
LINE PROTECTION
Classification of lines and Feeders
Line Classifications for Protection
Techniques and Equipment for Line Protection
Coordination Fundamentals and General Setting Criteria
Distribution Feeder, Radial Line Protection, and Coordination
Example: Coordination for a Typical Distribution Feeder
Independent Power Producer, DSGs, and Other Sources Connected for a Loop System
Example: Coordination for a Loop System
Instantaneous Trip Application for a Loop System
Short-Line Applications
Network and Spot Network Systems
Distance Protection for Phase Faults
Distance Relay Applications for Tapped and Multiterminal Lines
Voltage Sources for Distance Relays
Distance Relay Applications in Systems Protected by Inverse-Time-Overcurrent Relays
Ground-Fault Protection for Lines
Distance Protection for Ground Faults and Directional Overcurrent Comparison
Fault Resistance and Relaying
Directional Sensing for Ground-Overcurrent Relays
Polarizing Problems with Autotransformers
Voltage Polarization Limitations
Dual Polarization for Ground Relaying
Ground Directional Sensing with Negative Sequence
Mutual Coupling and Ground Relaying
Ground Distance Relaying with Mutual Induction
Long EHV Series-Compensated Line Protection
Backup: Remote, Local, and Breaker Failure
Summary: Typical Protection for Lines
Bibliography
PILOT PROTECTION
Introduction
Pilot System Classifications
Protection Channel Classifications
Directional Comparison Blocking Pilot Systems
Directional Comparison Unblocking Pilot System
Directional Comparison Overreaching Transfer Trip Pilot System
Directional Comparison Underreaching Transfer Trip Pilot Systems
Phase Comparison: Pilot Wire Relaying-Wire Line Channels
Phase Comparison: Audiotone on Fiber-Optic Channels
Segregated Phase Comparison Pilot Systems
Single-Pole-Selective-Pole Pilot Systems
Directional Wave Comparison Systems
Transfer Trip Systems
Communication Channels for Protection
Summary and General Evaluation of Pilot Systems
Bibliography
Appendix 1: Protection of Wire-Line Pilot Circuits
STABILITY, RECLOSING, AND LOAD SHIELDING
Introduction
Electric Power and Power Transmission
Steady-State Operation and Stability
Transient Operation and Stability
System Swings and Protection
Out-of-Step Detection by Distance Relays
Automatic Line Reclosing
Distribution Feeder Reclosing
Subtransmission and Transmission-Line Reclosing
Reclosing on Lines with Transformers or Reactors
Automatic Synchronizing
Frequency Relaying for Load-Shedding-Load-Saving
Frequency Relaying for Industrial Systems
Bibliography
PROBLEMS
INDEX