Transformer Engineering

Transcription

1 Transformer Engineering Design, Technology, and Diagnostics Second Edition S.V. Kulkarni S.A. Khaparde / 0 \ CRC Press \Cf*' J Taylor & Francis Group ^ч_^^ Boca Raton London NewYork CRC Press is an imprint of the Taylor St Francis Group, an informa business

2 Contents Preface to the second edition Foreword to the first edition Preface to the first edition Acknowledgments xi xiii xv xix Transformer Fundamentals Perspective Applications and Types of Transformers Principles and the Equivalent Circuit Representation of a Transformer in a Power System Open-Circuit and Short-Circuit Tests Voltage Regulation and Efficiency Parallel Operation of Transformers 34 References 36 Magnetic Characteristics Construction Hysteresis, Eddy, and Anomalous Losses Excitation Characteristics Over-Excitation Performance No-Load Loss Test Impact of Manufacturing Processes Inrush Current Influence of the Core Construction and Winding Connections on No-Load Harmonic Phenomenon Transformer Noise Rotational Core Losses 76 References 78 v

3 Impedance Characteristics Reactance Calculation Different Approaches for Reactance Calculation Analytical Methods Numerical Method for Reactance Calculation Impedance Characteristics of Three-Winding Transformers Reactance Calculation for Zigzag Transformers Zero-Sequence Reactances Stabilizing Tertiary Winding 129 References 132 Eddy Currents and Winding Stray Losses Field Equations Poynting Vector Eddy Current and Hysteresis Losses Effect of Saturation Eddy Losses in Transformer Windings Circulating Current Loss in Transformer Windings 165 References 176 Stray Losses in Structural Components Factors Influencing Stray Losses Overview of Methods for Stray Loss Estimation Core Edge Loss Stray Loss in Frames Stray Loss in Flitch Plates Stray Loss in Tank Stray Loss in Bushing Mounting Plates Evaluation of Stray Loss Due to High Current Leads Measures for Stray Loss Control Methods for Experimental Verification Estimation of Stray Losses in Overexcitation Condition Load Loss Measurement 229 References 235 Short-Circuit Stresses and Strength Short-Circuit Currents Thermal Capability during a Short-Circuit Short-Circuit Forces Dynamic Behavior under Short-Circuits Failure Modes Due to Radial Forces Failure Modes Due to Axial Forces 271

4 6.7 Failure Modes Due to Interactive (Combined Axial and Radial) Forces Effect of Prestress Short-Circuit Test Effect of Inrush Current Split-Winding Transformers Short-Circuit Withstand Calculation of Electrodynamic Force between Parallel Conductors Design of Clamping Structures 291 References 293 Surge Phenomena in Transformers Initial Voltage Distribution Ground Capacitance Calculations Capacitance of Windings Inductance Calculation Standing Waves and Traveling Waves Methods for Analysis of Impulse Distribution Computation of Impulse Voltage Distribution Using State Variable Method Winding Design for Reducing Internal Overvoltages 336 References 343 Insulation Design Calculation of Stresses for Simple Configurations Field Computations Factors Affecting Insulation Strength Test Methods and Design Insulation Level (DIL) Insulation between Two Windings Internal Insulation Design of End Insulation High-Voltage Lead Clearances Statistical Analysis for Optimization and Quality Enhancement 385 References 387 Cooling Systems Modes of Heat Transfer Cooling Arrangements Dissipation of Core Heat Dissipation of Winding Heat Aging and Life Expectancy 406

5 VIII 9.6 Direct Hot Spot Measurement Static Electrification Phenomenon Recent Trends in Computations 414 References Structural Design Importance of Structural Design Different Types of Loads and Tests Classification of Transformer Tanks Tank Design Methods of Analysis Overpressure Phenomenon in Transformers Seismic Analysis Transformer Noise: Characteristics and Reduction Transport Vibrations and Shocks 442 References Special Transformers Rectifier Transformers Converter Transformers for HVDC Furnace Transformers Phase Shifting Transformers 463 References Electromagnetic Fields in Transformers: Theory and 471 Computations 12.1 Perspective Basics of Electromagnetic Fields Relevant to Transformer Engineering Potential Formulations Finite Element Method FEM Formulations Coupled Fields in Transformers Computation of Performance Parameters 552 References Transformer-System Interactions and Modeling Power Flow Analysis with Transformers Harmonic Studies Ferroresonance Arc Furnace Application 587

6 Contents ix 13.5 Geomagnetic Disturbances Sympathetic Inrush Phenomenon Internal Resonances Due to System Transients Very Fast Transient Overvoltages Transients in Distribution Transformers Low-, Mid-, and High-Frequency Models of Transformers 593 References Monitoring and Diagnostics Conventional Tests Dissolved Gas Analysis Partial Discharge Diagnostics Degree of Polymerization and Furan Analysis Time Domain Dielectric Response Methods Frequency Domain Dielectric Response Method Detection of Winding Displacements Accessories Other Diagnostic Tests/Instruments Life Assessment and Refurbishment 659 References Recent Trends in Transformer Technology Magnetic Circuit Windings New Insulating Liquids Advanced Computations Transformers for Renewable Energy Applications Applications of Power Electronics Other Technologies Trends in Monitoring and Diagnostics 676 References 678 Appendix A: Sample Design 681 Appendix B: Vector Groups 701 Appendix C: Fault Calculations 705 Appendix D: Stress and Capacitance Formulae 711 Index 721