Electric Power Engineering

462 Pages·1998·14.317 MB·English

by  Olle I. Elgerd, Patrick D. van der Puije (auth.)

lectric Power
Engineering
Oile 1. Eigerd
Recently retired
FlICuIty 01 Engineering
UniYersity of F\oIidc'I
G/llr'IeSV1lle:, Florida
Patrick O. van d er Puije
DE:partment of Electronics
Cl!rleton University
Otta'N", Ont<'lrio, CdMda
Cover design: Curtis Tow Graphics
Copyright © 1998 by Springer Science+Business Media Dordrecht
Originally published by Chapman & Hali in 1998
Softcover reprint of the hardcover 2nd edition 1998
A11 rights reserved. No part of this book covered by the copyright hereon may be reproduced or used in
any form or by any means-graphic, electronic, or mechanical, including photocopying, recording, taping,
or information storage and retrieval systems-without the written permission of the publisher.
1 2 3 4 5 6 7 8 9 10 XXX 01 00 99 98
Library of Congress Cataloging-in-Publication Data
Elgerd, Oile Ingemar, 1925-
Electric power engineering / Oile J. Elgerd, P.D. van der Puije. -
- 2nd ed.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4613-7747-4 ISBN 978-1-4615-5997-9 (eBook)
DOI 10.1007/978-1-4615-5997-9
1. Electric engineering. 1. Van der Puije, Palrick D., 1937-
TK146.E44 1997
621.31-dc21 97-69
CIP
British Library Cataloguing in Publication Data available
"Electric Power Engineering" is intended to present technica11y accurate and authoritative information
from highly regarded sources. The publisher, editors, authors, and contributors have made every reason
able effort to ensure the accuracy of the information, but cannot assume responsibility for the accuracy
of a11 information, or for the consequences of its use.
Contents
Preface xv
CHAPTER 1
Energy: The Basis of Civilization 1
1.1 Historical Perspective I
1.2 Energy Flow in Industrialized Societies 3
1.3 The Growth of Energy Consumption 5
1.4 Electric Energy 8
1.4.1 Hydroelectric Power 10
1.4.2 Electricity from Fossil Fuel 11
1.4.3 Electric Power Generation from Nuclear
Reaction 13
1.4.4 Electric Energy Storage 13
1.5 Summary 14
Exercises IS
References 15
CHAPTER 2
Fundamentals of Energy 16
2.1 Energy and Gravitation 16
2.2 Gravitational Force Field . 17
2.3 Gravitational Energy Exchange: Definition of Energy 20
2.4 Gravitational Potential: Potential Energy 22
2.5 General Expressions for Energy 24
2.6 Rate of Energy or Power 25
2.7 The Law of Conservation of Energy: First Law
of Thermodynamics 29
2.8 Other Forms of Potential Energy 32
2.9 Forms of Kinetic Energy 36
v
vi Contents
2.10 Caloric (Heat or Thermal) Energy 38
2.10.1 Ordered and Disordered Forms of Energy 38
2.10.2 Reversible and Nonreversible Energy
Transformations: Second Law
Of Thermodynamics 38
2.10.3 The Caloric Energy Equivalent 39
2.11 Energy Dissipation 42
2.12 Nuclear Energy 44
2.13 Solar Energy 46
2.14 Summary 48
Exercises 48
References 51
CHAPTER 3
Fundamentals of Electric Energy 52
3.1 Electric Energy Engineering 52
3.2 Physical Nature of Electricity: Electric Charge 53
3.3 Coulomb's Law: The Gravity Analog 54
3.4 The Electric Field 56
3.5 Electrostatic Energy 56
3.6 Electric Potential 58
3.7 General Field Configurations 60
3.8 Electrostatic Energy Storage: Capacitance 63
3.9 Practical Electric Capacitors 66
3.10 Electrodynamics: Electric Current 70
3.11 Currents in Electric Conductors 72
3.12 Ohm's Law 73
3.13 Basics of Electric Power 74
3.14 Resistive or Ohmic Power Dissipation 75
3.15 Electric Power Transmission 75
3.16 Electric Sources 76
3.17 The Magnetic Field 81
3.18 Magnetic Flux 84
3.19 Electromagnetic Induction: Faraday's and Lenz's
Laws 86
3.19.1 Voltage Induced in a Coil Rotating in a Uniform
Magnetic Field 90
3.20 The Electromagnetic Force Law 93
3.20.1 Torque on a Coil in a Magnetic Field 94
3.20.2 Force Between Two Long Parallel
Conductors 95
Contents vii
3.21 The Concept of Mutual Inductance 97
3.22 The Concept of Self-Inductance 98
3.23 Electromagnetic Energy Storage 99
3.24 Magnetic Energy Storage in Mutually Coupled
Circuits 101
3.25 The Magnetic Moment 102
3.26 Ferromagnetism 104
3.26.1 Magnetic "Conduction" 104
3.26.2 Ohm's Law for a Magnetic Circuit 105
3.26.3 The Magnetic Field Intensity 109
3.26.4 Magnetization Curves for Ferrous Materials 110
3.26.5 A Physical Explanation of Ferromagnetism 113
3.26.5.1 Magnetization: A Result of Line-up
of Atomic Magnetic Moments 113
3.26.5.2 "Bound" Currents 114
3.26.5.3 The Effects of Magnetized Material
on Force and Torque 116
3.27 Summary 118
Exercises 119
References 125
CHAPTER 4
Synchronous Machine 126
4.1 Direct Current Versus Alternating Current 126
4.2 Power in Single-Phase Alternating Current 129
4.2.1 Real and Reactive Powers 129
4.2.2 Effects of Various Types of Load 131
4.2.3 The Concept of Complex Power 134
4.3 The Single-Phase Alternating-Current Generator 135
4.3.1 Alternating-Current Generator Design 135
4.3.2 Frequency, Poles, and Speed 138
4.3.3 Saliency and Nonsaliency 139
4.3.4 The Air-Gap Flux in Terms of Rotor
Coordinates 140
4.3.5 The Traveling Flux Wave 142
4.3.6 The Induced Electromotive Force in the
Stator 143
4.3.7 Distribution Effects 145
4.4 The Three-Phase Generator 148
4.4.1 Three-Phase Winding Design 151
4.4.2 Phase and Line Voltages 154
viii Contents
4.5 Balanced Three-Phase Loading 156
4.5.1 Balanced Loading Between Phase Terminals And
Ground (Y -Connected Load) 157
4.5.2 Balanced Loading Between Phase Terminals
(a-Connected Load) 159
4.5.3 The Generator Operating as Part of a Power Grid 162
4.6 Torque Mechanism in a Three-Phase Generator 163
4.6.1 The Stator "Current Wave" 164
4.6.2 Torque and Power 165
4.6.3 Some Practical Observations 167
4.6.4 Power and the Angle y 168
4.7 The Synchronous Machine as Part of a Power Grid 169
4.7.1 Synchronization of the Machine to the Grid 171
4.7.2 Synchronous Machine Control 174
4.7.2.1 Effects of Prime Mover Torque 174
4.7.2.2 Effects of Field-Current Control 176
4.7.2.3 Summary 176
4.7.3 PhasorDiagram 176
4.7.4 Practical Expressions for Power 180
4.7.5 Pullout Power 181
4.8 Summary and Some Final Observations 184
Exercises 187
References 189
CHAPTERS
The Power Transformer 190
5.1 Why Transformers? 190
5.2 The Single-Phase Transformer: Basic Design 193
5.3 The Concept of an "Ideal" Transformer 193
5.3.1 The Ideal Transformer on No-Load 194
5.3.1.1 Voltage Relationships 194
5.3.1.2 Magnetic Flux in a Sinusoidally Excited
Transformer 195
5.3.1.3 Voltage per Tum 195
5.3.1.4 Transformer Size and Frequency 196
5.3.2 The Ideal Transformer Under Loaded
Conditions 197
5.3.2.1 Voltage, Current, and Flux 197
5.3.2.2 Power 198
5.3.2.3 The Ideal Transformer as an Impedence
Transformer 199
Contents ix
5.3.2.4 Equivalent Circuit of the Ideal
Transformer 200
5.3.2.5 A Mechanical Analog of the Ideal
Transformer 201
5.4 The Physical Transformer: The Ideal Transformer 202
5.4.1 Finite Permeability 202
5.4.1.1 The Magnetization Current 202
5.4.1.2 The Magnetization Reactance 203
5.4.1.3 Adjustment of the Ideal Transformer
Equivalent Ciruit to Include the
Magnetization Reactance 204
5.4.2 Core Losses 205
5.4.3 Effects of Core Nonlinearity 205
5.4.4 Modeling of the Winding Losses 207
5.4.5 Measurement of Transformer Losses 209
5.4.5.1 The Open-Circuit Test 209
5.4.5.2 The Short-Circuit Test 209
5.5 Some Practical Design Considerations 213
5.5.1 Core and Coil Design 213
5.5.2 Cooling Methods 214
5.5.3 Transformer Ratings 215
5.6 Multiwinding Transformers 216
5.7 Autotransformers 218
5.8 Three-Phase Power Transformers 219
5.8.1 Single-Phase Units Connected Y-Y
(Bank Arrangement) 221
5.8.2 Three-Phase Core Arrangement 223
5.8.3 The .:l-Y Connection 223
5.8.4 Equivalent Circuits for Three-Phase
Transformers 231
5.9 Summary 233
Exercises 234
References 238
CHAPTER 6
The Electric Power Network 239
6.1 The Structure of the Power Network 240
6.2 Objectives of Power System Operation 244
6.3 Real Power Balance: The Load-Frequency Control
Problem 244
6.3.1 Load Characteristics 245
x Contents
6.3.2 Load-Frequency Dynamics 246
6.3.3 A Mechanical Analog 247
6.3.4 Automatic Load Frequency Control 248
6.4 Optimum Generation 250
6.5 Line Power and Its Control 251
6.5.1 Line Parameters 252
6.5.2 Control of the Line Voltage Profile 256
6.5.3 Control of Real Line Power 257
6.5.4 Synchronization Coefficient 260
6.5.5 Control of Reactive Line Power 261
6.5.6 Real Power Losses 263
6.5.7 Summary of Interesting and Important
Observations 266
6.6 Load Flow Analysis 266
6.6.1 Load Flow Analysis Is Not a "Standard" Circuits
Problem 267
6.7 Summary 269
Exercises 270
References 273
CHAPTER 7
The Direct Current Machine 274
7.1 Torque-Speed Requirements of Motors 274
7.2 A Direct Current Motor Prototype 276
7.2.1 Steady-State Speed Under No-Load
Conditions 277
7.2.2 Energy Transformation in Direct Current Motors 278
7.2.3 The Linear Direct Current Motor Under Load 278
7.2.4 Motor Rating 279
7.2.5 Turning the Motor into a Generator 280
7.2.6 Equivalent Circuits 280
7.3 Physical Motor Design 280
7.3.1 The Homopolar Machine 281
7.3.2 Cylindrical Conductor Direct Current Motor 285
7.3.3 The Commutator Action 288
7.3.4 The Motor Torque (Tm) 290
7.3.5 The Induced Electromotive Force 292
7.3.6 The Motor Power (Pm) 294
7.3.7 The Equivalent Circuit of the Motor 295
7.3.8 Additional Losses 297
7.3.8.1 Rotational Losses 297
Contents xi
7.3.8.2 Field Losses 297
7.3.8.3 Stray Losses 297
7.4 Operating Characteristics of the Direct Current Machine 299
7.4.1 Starting the Direct Current Motor 300
7.4.2 The Separately Excited Direct Current Machine
Operated as a Generator 300
7.4.3 The Torque-Speed Characteristics of the Separately
Excited Direct Current Machine 302
7.4.4 The Torque-Speed Characteristics of the Shunt
Direct Current Motor 305
7.4.5 Speed Control of a Direct Current Motor 306
7.4.5.1 Speed Control by Variation of Applied
Voltage (Va) 307
7.4.5.2 Speed Control by Variation of Field
Resistance 307
7.4.6 The Shunt Generator Feeding a Resistive
Load 309
7.4.7 The Series-Excited Direct Current Machine 313
7.4.8 The "Universal" Motor 315
7.5 Direct Current Power Supply Systems 315
7.5.1 Basic Rectifier Elements 316
7.5.1.1 The Diode 316
7.5.1.2 The Thyristor 317
7.5.2 Single-Phase, Half-Wave Rectifier Circuits 318
7.5.2.1 Diode Circuit 318
7.5.2.2 Thyristor Circuit 319
7.5.3 Single-Phase, Full-Wave Rectifier Circuits 319
7.5.4 Three-Phase Rectifier Circuits 321
7.6 Summary 321
Exercises 322
References 325
CHAPTER 8
Induction Machines 326
8.1 Why Induction Motors? 326
8.2 Basic Design Features 326
8.3 The Rotating Stator Flux Wave 328
8.3.1 Harmonics of the Flux 328
8.4 The Torque-Creating Mechanism 329
8.4.1 The Rotor Currents at Standstill 330
8.4.2 The Motor Torque 331
xii Contents
8.4.3 Current Wave In the Running Rotor: Concept of
Slip 333
8.4.4 Torque as a Function of Slip: A Qualitative
Analysis 333
8.4.5 Determination of Motor Operating Speed 335
8.4.6 The Induction Generator 336
8.4.7 "Wound-Rotor" Induction Motors 337
8.5 Three-Phase Induction Motor Performance Analysis 339
8.5.1 The Transformer as an Analog of the Induction
Motor 339
8.5.2 The Concept of an "Ideal Motor" 340
8.5.3 Circuit Equations for the Ideal Motor 342
8.5.4 Equivalent Circuit of the Ideal Motor 344
8.5.5 The Circle Diagram for the Ideal Motor 345
8.5.6 Motor Power and Torque in the Ideal Motor 349
8.5.7 Maximum Torque of the Ideal Motor 350
8.5.8 Torque Control by Variation of Rotor
Resistance 353
8.6 Modification of the Model for Nonideal Motor
Characteristics 354
8.6.1 Inaccuracy of the Ideal Motor Model at Light
Load 354
8.6.2 Existence of Excitation or Magnetization
Current 354
8.6.3 Modification of the Ideal Motor Equivalent
Circuit 355
8.6.4 The Effect of the Circuit Modification on the Circle
Diagram 355
8.7 Operational Considerations 360
8.7.1 High Starting Current During Direct Start 360
8.7.1.1 Insertion of External Rotor
Resistance 361
8.7.1.2 Using a Starting Compensator 361
8.7.1.3 The Y-A Starting Method 362
8.7.2 Efficiency at Low Speed 362
8.7.3 Torque-Speed Control 364
8.7.3.1 Speed Control by Voltage Variation 365
8.7.3.2 Speed Control by Rotor Rheostat
Adjustment 365
8.8 Single-Phase Induction Motors 365
8.8.1 Stator Flux as a Function of Time and
Distance 365