1st Edition

Protective Relaying for Power Generation Systems

By Donald Reimert Copyright 2006
    592 Pages 361 B/W Illustrations
    by CRC Press

    Power outages have considerable social and economic impacts, and effective protection schemes are crucial to avoiding them. While most textbooks focus on the transmission and distribution aspects of protective relays, Protective Relaying for Power Generation Systems is the first to focus on protection of motors and generators from a power generation perspective. It also includes workbook constructions that allow students to perform protection-related calculations in Mathcad® and Excel®.

    This text provides both a general overview and in-depth discussion of each topic, making it easy to tailor the material to students' needs. It also covers topics not found in other texts on the subject, including detailed time decrement generator fault calculations and minimum excitation limit. The author clearly explains the potential for damage and damaging mechanisms related to each protection function and includes thorough derivations of complex system interactions. Such derivations underlie the various rule-of-thumb setting criteria, provide insight into why the rules-of-thumb work and when they are not appropriate, and are useful for post-incident analysis. The book's flexible approach combines theoretical discussions with example settings that offer quick how-to information.

    Protective Relaying for Power Generation Systems integrates fundamental knowledge with practical tools to ensure students have a thorough understanding of protection schemes and issues that arise during or after abnormal operation.

    GENERATOR NORMAL OPERATIONS
    The Sample System
    Generator Capability
    Voltage Limitations
    System Limitations
    Generator Capability Variations with Voltage
    Excitation System
    References
    GENERATOR SHORT CIRCUIT CALCULATIONS
    Introduction
    Short-Circuit Current Characteristics
    Generator Internal Magnetics
    Generator Magnetic Structures
    Generator Constants
    Fault Current Calculations
    Voltage Regulator
    Practical Shortcuts
    Short Circuit Calculation Example
    References
    GENERATOR DIFFERENTIAL RELAY: 87G
    Introduction
    Ideal Differential Relay
    Practical Considerations
    Percentage Differential Relay
    Relay Characteristics
    Minimum Operating Current Setting
    Slope Setting
    Sample System Differential Relay Settings
    CT Saturation
    Stabilizing Resistor
    Balancing Burden
    Time Delay
    Frequency Response
    References
    BACKUP FAULT PROTECTION
    Purpose and Implementation
    Voltage Supervised Overcurrent Relays
    Distance Relays
    References
    GENERATOR GROUND FAULT PROTECTION
    Introduction
    Generator Grounding Considerations
    Methods of Grounding
    Ground Fault Protection
    References
    UNBALANCED CURRENT PROTECTION
    Introduction
    What is Negative-Sequence Current?
    Effects of Negative-Sequence Current
    Generator Negative-Sequence Capability
    Sources of Negative-Sequence Current
    In-Service (I2)^2t Duty Versus Standards
    Unbalanced Current Protection
    Negative-Sequence Relay Settings
    References
    MOTORING PROTECTION
    Introduction
    Effects of Motoring
    Protection
    Sequential Trip Logic
    Backup Protection
    Setting Device 32
    Applying Reversed Power Relay on the Sample System
    References
    FIELD WINDING PROTECTION
    Field Ground Protection
    Field Overcurrent Protection
    Settings for Field Overcurrent Overvoltage Relays
    Applying Field OC Protection on the Sample System
    References
    OVEREXCITATION
    Introduction
    Causes of Overexcitation
    Damage
    V/Hz Limits
    Protection
    Settings
    Differential Relay Response to Overexcitation
    Application of V/Hz Protection on the Sample System
    References
    ABNORMAL FREQUENCY PROTECTION
    Introduction
    Effect on Generator
    Steam Turbines
    Combustion Turbines
    Hydro Generators
    Excitation System
    Protection and Settings
    References
    MINIMUM EXCITATION LIMITER
    Overview of the Minimum Excitation Limiter Application
    Setting Criteria Background
    Setting Criteria
    Steady State and Dynamic Stability Considerations
    Generator Leading VAR Capability
    Coordination with the LOF Relay
    System Stability Limits
    MEL Protective Characteristic
    MEL Dynamic Performance
    MEL Application on the Sample System
    References
    LOSS OF SYNCHRONISM
    Introduction
    Turbine Generator Damage
    Transient Stability
    Out-of-Step Protection
    Classical Swing Impedance Characteristic
    Dynamic Swing Representation
    Dynamic Swing Calculations
    Setting Consideration
    Out-of-Step Relay: Device 78
    Setting Out-of-Step on Sample System
    References
    LOSS OF FIELD PROTECTION
    General
    System Impact
    Generator Damage
    Loss of Field Protection: Device 40
    Distance Relay Schemes
    Other Causes for LOF Relay Operations
    LOF Relays During System Disturbances
    Special Considerations for Hydro Units
    Application of the LOF on the Sample System
    References
    SYNCHRONIZATION PROTECTION
    Introduction
    Damage
    Synchronizing Methods
    Synchronism Check Relays (Device 25)
    Automatic Synchronizer (Device 25A)
    Slow Breaker Protection
    Settings
    Synchronizing Equipment on the Sample System
    References
    ACCIDENTAL ENERGIZATION PROTECTION
    Introduction
    Generator State at Energization
    Inadvertent Energization
    Breaker Flashover
    Dynamic Analysis of Three-Phase Energization from Standstill
    Generator Damage
    Turbine Damage
    Energization Protection
    Protection Provided by Native Schemes
    Dedicated Energization Protection
    Applying Energization Protection on the Sample System
    References
    MOTOR PROTECTION
    Introduction
    Motor Characteristics And Representation
    Motor Ratings
    Motor Characteristics
    Motor Applications
    Motor Starting
    Mechanic System Considerations
    Pump Characteristics
    Motor Overload Protection
    Multifunction Microprocessor Relays
    Transient Current Evaluation
    Special Schemes for Difficult Starts
    Direct Temperature Measurement
    Phase Fault Protection
    Ground Fault Protection
    Phase Unbalanced Protection
    Sample Setting Calculations
    References
    APPENDIX A: SWING IMPEDANCE LOCUS CALCULATION USING EXCEL®
    APPENDIX B
    APPENDIX C
    APPENDIX D
    APPENDIX E
    APPENDIX F
    INDEX

    Biography

    Reimert, Donald

    "…covers a wide range of topics and can help the reader to achieve basic understanding or deep knowledge of generator and motor protection, thus meeting the needs of both students and professionals… The author… has worked for more than 35 years in the design not only of generator and motor protection systems, but also substation, transmission, and distribution facilities. His system planning experience as well as the preparation and teaching of different protection related courses at the University of Wisconsin-Milwaukee allow him to present the material in the book in a clear and practical manner."

    —PAC World Magazine

     

    "Power engineers and application engineers who work with generator protective devices as well as power engineering students would find this book to be a great hands-on reference that reveals a wealth of information on generator protective relaying for power systems."

    – John J. Shea, in IEEE Electrical Insulation Magazine, September/October 2007, Vol. 23, No. 5