El-Hawary, M.E.

“Frontmatter”
Electrical Energy Systems.
Series Ed. Leo Grigsby
Boca Raton: CRC Press LLC, 2000
Electrical
Energy
Systems
TheThe
ELECTRIC
POWERPOWER ENGINEERING
ENGINEERING Series
Series
serieseditor
series editorLeo
LeoGrigsby
Grigsy

Published Titles

Electromechanical Systems, Electric Machines,

and Applied Mechatronics
Sergey E. Lyshevski

Electrical Energy Systems

Mohamed E. El-Hawary

Forthcoming Titles
Handbook of Induction Machines
Ion Boldea and Syed Nasar

Distribution System Modeling and Analysis

William H. Kersting

Power System Operations and Planning

in a Restructured Business Environment
Fred I. Denny and David E. Dismukes

Linear Synchronous Motors:

Transportation and Automation Systems
Jacek Gieras and Jerry Piech
 Electrical
Energy
Systems

Mohamed E. El-Hawary
Dalhousie University

CRC Press
Boca Raton London New York Washington, D.C.
 Table of Contents

Preface

Chapter 1 – INTRODUCTION……….1
1.1 A Brief History of Electric Power Systems……….1
1.2 The Structure of the Power System……….3
1.3 Outline of the Text……….7

Chapter 2 – BASICS OF ELECTRIC ENERGY SYSTEM THEORY……9

2.1 Introduction……….9
2.2 Concepts of Power in Alternating Current Systems……….9
2.3 Three-Phase Systems……….14
2.4 The Per Unit System……….24
2.5 Electromagnetism and Electromechanical Energy
Conversion……….27
2.6 Permeability and Magnetic Field Intensity……….30
2.7 Flux Linkages, Induced Voltages, Inductance, and
Energy……….34
2.8 Hysteresis Loop……….36
2.9 Eddy Current and Core Losses……….37
2.10 Energy Flow Approach……….40
2.11 Multiply Excited Systems……….44
2.12 Doubly Excited Systems……….45
2.13 Salient-Pole Machines……….47
2.14 Round or Smooth Air-Gap Machines……….49
2.15 Machine-Type Classification……….52
2.16 P-Pole Machines……….54
2.17 Power System Representation……….58

Problems……….59

Chapter 3 – POWER GENERATION AND THE SYNCHRONOUS

MACHINE……….69
3.1 Introduction……….69
3.2 The Synchronous Machine: Preliminaries……….67
3.3 Synchronous Machine Fields……….72
3.4 A Simple Equivalent Circuit……….74
3.5 Principal Steady-State Characteristics……….77
3.6 Power-Angle Characteristics and the Infinite Bus
Concept……….79
3.7 Accounting for Saliency……….86
3.8 Salient-Pole Machine Power Angle Characteristics……….90

Problems……….93

Chapter 4 – THE TRANSFORMER……….97

4.1 Introduction……….97
4.2 General Theory of Transformer Operation……….97
 4.3 Transformer Connections……….111

Problems……….121

Chapter 5 – ELECTRIC POWER TRANSMISSION……….125

5.1 Introduction……….125
5.2 Electric Transmission Line Parameters……….125
5.3 Line Inductance……….127
5.4 Line Capacitance……….145
5.5 Two-Port Networks……….161
5.6 Transmission Line Models……….163

Problems……….179

Chapter 6 – INDUCTION AND FRACTIONAL HORSEPOWER

MOTORS……….185
6.1 Introduction……….185
6.2 Three-Phase Induction Motors……….185
6.3 Torque Relations……….193
6.4 Classification of Induction Motors……….198
6.5 Rotating Magnetic Fields in Single-Phase Induction
Motors……….199
6.6 Equivalent Circuits for Single-Phase Induction Motors…204
6.7 Power and Torque Relations……….210
6.8 Starting Single-Phase Induction Motors……….216
6.9 Single-Phase Induction Motor Types……….218

Problems……….225

Chapter 7 – FAULTS AND PROTECTION OF ELECTRIC ENERGY

SYSTEMS……….231
7.1 Introduction……….231
7.2 Transients During a Balanced Fault……….232
7.3 The Method of Symmetrical Components……….235
7.4 Sequence Networks……….239
7.5 Line-to-Ground Fault……….255
7.6 Double Line-to-Ground Fault……….258
7.7 Line-to-Line Fault……….262
7.8 The Balanced Three-Phase Fault……….264
7.9 System Protection, An Introduction……….265
7.10 Protective Relays……….267
7.11 Transformer Relay……….270
7.12 Transmission Line Protection……….276
7.13 Impedance-Based Protection Principles……….283
7.14 Computer Relaying……….291

Problems……….293

Chapter 8 – THE ENERGY CONTROL CENTER……….299

 8.1 Introduction……….299
8.2 Overview of EMS Functions……….301
8.3 Power Flow Control……….309
8.4 Power Flow……….313
8.5 Stability Considerations……….326
8.6 Power System State Estimation……….334
8.7 Power System Security……….338
8.8 Contingency Analysis……….343
8.9 Optimal Preventive and Corrective Actions……….346
8.10 Dynamic Security Analysis……….355

References……….361
 Preface

This book is written primarily as an introduction to electrical energy

systems. It is intended for students in electrical and other engineering
disciplines, as well as being useful as a reference and self-study guide for the
professional dealing with this important area. The coverage of the book is
designed to allow its use in a number of ways including service courses taught to
non-electrical majors. The organization and details of the material in this book
enables maximum flexibility for the instructor to select topics to include in
courses within the modern engineering curriculum.

The book does not assume a level of mathematical awareness beyond

that given in undergraduate courses in basic physics and introductory electric
circuits. Emphasis is given to an improved appreciation of the operational
characteristics of the electrical apparatus discussed, on the basis of linear
mathematical models. Almost every key concept is illustrated through the use
of in-text examples that are worked out in detail to enforce the reader’s
understanding. The text coverage includes some usage of MATLAB to solve
fundamental problems of basic performance characteristics to obtain analysis of
power system devices.

The first chapter in this book provides a historical perspective on the

development of electric power systems. While this topic is not an integral part
of the conventional coverage in texts and courses in this area, this chapter should
provide interesting insights into the influence of these developments on present
day civilization. It is through an appreciation of the past developments and
achievements that we can understand our present and forge ahead with future
advances.

Chapters 2 to 8 deal with fundamental topics to be covered in courses

in electric energy systems. Emphasis is given to practical aspects such as the
main performance characteristics of the devices discussed and system
applications. The importance of computer control in power system operations is
highlighted in Chapter 8 where we discuss the structure and functions involved
in a modern energy control center.

I have attempted to make this book as self-containing as possible. As a

result, the reader will find that many background topics such as the per unit
system and three-phase circuits are included in the text’s main body as opposed
to the recent trend toward including many appendices dealing with these topics.
In studying and teaching electrical energy systems it has been my experience
that a problem solving approach is most effective in exploring this rich area.

A textbook such as this could not have been written without the
continuing input of the many students who have gone through many versions of
its material as it was developed. My sincere thanks to the members of the many
classes to whom I was privileged to teach this fascinating subject. I wish to
acknowledge the able work of Elizabeth Sanford of DalTech in putting this
manuscript in a better form than I was able to produce. My association with the
CRC Press LLC staff has been valuable throughout the many stages of preparing
this text. I wish to express my appreciation to Nora Konopka and her
continuous encouragement and support.

I owe a debt of gratitude to Dr. Leo Grigsby of Auburn University for

suggesting that I write this book.

It is always a great pleasure to acknowledge with thanks the continuing

support of Dean Adam Bell of DalTech during the course of preparing this text.
As has always been the case, the patience and understanding of my wife Dr.
Ferial El-Hawary made this project another joy to look forward to completing.
It goes without saying that our sons and daughter deserve a greater share of my
appreciation for their continuous understanding.

M.E. El-Hawary