POWER SYSTEM ANALYSIS AND DESIGN pdf

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POWER SYSTEM ANALYSIS
AND DESIGN
FIFTH EDITION, SI
J. DUNCAN GLOVER
FAILURE ELECTRICAL, LLC
MULUKUTLA S. SARMA
NORTHEASTERN UNIVERSITY
THOMAS J. OVERBYE
UNIVERSITY OF ILLINOIS
Australia • Brazil • Japan • Korea • Mexico • Singapore • Spain • United Kingdom • United States
Power System Analysis and Design,
Fifth Edition, SI
J. Duncan Glover, Mulukutla S. Sarma,
and Thomas J. Overbye
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Christopher M. Shortt
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TO LOUISE, TATIANA & BRENDAN, ALISON & JOHN, LEAH, OWEN,
ANNA, EMILY & BRIGID
Dear Lord! Kind Lord!
Gracious Lord! I pray
Thou wilt look on all I love,
Tenderly to-day!

Weed their hearts of weariness;
Scatter every care
Down a wake of angel-wings
Winnowing the air.
Bring unto the sorrowing
All release from pain;
Let the lips of laughter
Overflow again;
And with all the needy
O divide, I pray,
This vast treasure of content
That is mine to-day!
James Whitcomb Riley
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CONTENTS
Preface to the SI Edition xii
Preface xiii
List of Symbols, Units, and Notation xix
CHAPTER 1
Introduction 1
Case Study: The Future Beckons: Will the Electric Pow er
Industry Heed the Call? 2
1.1 History of Electric Power Systems 10
1.2 Present and Future Trends 17
1.3 Electric Utility Industry Structure 21
1.4 Computers in Power System Engineering 22
1.5 PowerWorld Simulator 24
CHAPTER 2
Fundamentals 31
Case Study: Making Microgrids Work 32

2.1 Phasors 46
2.2 Instantaneous Power in Single-Phase AC Circuits 47
2.3 Complex Power 53
2.4 Network Equations 58
2.5 Balanced Three-Phase Circuits 60
2.6 Power in Balanced Three-Phase Circuits 68
2.7 Advantages of Balanced Three-Phase Versus
Single-Phase Systems 74
CHAPTER 3
Power Transformers 90
Case Study: PJM Manages Aging Transformer Fleet 91
3.1 The Ideal Transformer 96
3.2 Equivalent Circuits for Practical Transformers 102
3.3 The Per-Unit System 108
3.4 Three-Phase Transformer Connections and Phase Shift 116
3.5 Per-Unit Equivalent Circuits of Balanced Three-Phase
Two-Winding Transformers 121
3.6 Three-Winding Transformers 126
3.7 Autotransformers 130
3.8 Transformers with O¤-Nominal Turns Ratios 131
vii
CHAPTER 4 Transmission Line Parameters 159
Case Study: Transmission Line Conductor Design Comes of Age 160
Case Study: Six Utilities Share Their Perspectives on Insulators 164
4.1 Transmission Line Design Considerations 169
4.2 Resistance 174
4.3 Conductance 177
4.4 Inductance: Solid Cylindrical Conductor 178
4.5 Inductance: Single-Phase Two-Wire Line and Three-Phase
Three-Wire Line with Equal Phase Spacing 183

4.6 Inductance: Composite Conductors, Unequal Phase Spacing,
Bundled Conductors 185
4.7 Series Impedances: Three-Phase Line with Neutral Conductors
and Earth Return 193
4.8 Electric Field and Voltage: Solid Cylindrical Conductor 199
4.9 Capacitance: Single-Phase Two-Wire Line and Three-Phase
Three-Wire Line with Equal Phase Spacing 201
4.10 Capacitance: Stranded Conduc tors, Unequal Phase Spacing,
Bundled Conductors 204
4.11 Shunt Admittances: Lines with Neutral Conductors
and Earth Return 207
4.12 Electric Field Strength at Conductor Surfaces
and at Ground Level 212
4.13 Parallel Circuit Three-Phase Lines 215
CHAPTER 5
Transmission Lines: Steady-State Operation 233
Case Study: The ABCs of HVDC Transmission Technologies 234
5.1 Medium and Short Line Approximations 248
5.2 Transmission-Line Di¤erential Equations 254
5.3 Equivalent p Circuit 260
5.4 Lossless Lines 262
5.5 Maximum Power Flow 271
5.6 Line Loadability 273
5.7 Reactive Compensation Techniques 277
CHAPTER 6
Power Flows 294
Case Study: Future Vision 295
Case Study: Characteristics of Wind Turbine Generators
for Wind Power Plants 305
6.1 Direct Solutions to Linear Algebraic Equations:

Gauss Elimination 311
6.2 Iterative Solutions to Linear Algebraic Equations:
Jacobi and Gauss–Seidel 315
6.3 Iterative Solutions to Nonlinear Algebraic Equations:
Newton–Raphson 321
viii
CONTENTS
6.4 The Power-Flow Problem 325
6.5 Power-Flow Solution by Gauss–Seidel 331
6.6 Power-Flow Solution by Newton–Raphson 334
6.7 Control of Power Flow 343
6.8 Sparsity Techniques 349
6.9 Fast Decoupled Power Flow 352
6.10 The ‘‘DC’’ Power Flow 353
6.11 Power-Flow Modeling of Wind Generation 354
Design Projects 1–5 366
CHAPTER 7
Symmetrical Faults 379
Case Study: The Problem of Arcing Faults in Low-Voltage
Power Distribution Systems 380
7.1 Series R–L Circuit Transients 382
7.2 Three-Phase Short Circuit—Unloaded
Synchronous Machine 385
7.3 Power System Three-Phase Short Circuits 389
7.4 Bus Impedance Matrix 392
7.5 Circuit Breaker and Fuse Selection 400
Design Project 4 (continued ) 417
CHAPTER 8
Symmetrical Components 419
Case Study: Circuit Breakers Go High Voltage 421

8.1 Definition of Symmetrical Components 428
8.2 Sequence Networks of Impedance Loads 433
8.3 Sequence Networks of Series Impedances 441
8.4 Sequence Networks of Three-Phase Lines 443
8.5 Sequence Networks of Rotating Machines 445
8.6 Per-Unit Sequence Models of Three-Phase
Two-Winding Transformers 451
8.7 Per-Unit Sequence Models of Three-Phase
Three-Winding Transformers 456
8.8 Power in Sequence Networks 459
CHAPTER 9
Unsymmetrical Faults 471
Case Study: Fires at U.S. Utilities 472
9.1 System Representation 473
9.2 Single Line-to-Ground Fault 478
9.3 Line-to-Line Fault 483
9.4 Double Line-to-Ground Fault 485
9.5 Sequence Bus Impedance Matrices 492
Design Project 4 (continued ) 512
Design Project 6 513
CONTENTS ix
CHAPTER 10 System Protection 516
Case Study: The Future of Power Transmission 518
10.1 System Protection Components 525
10.2 Instrument Transformers 526
10.3 Overcurrent Relays 533
10.4 Radial System Protection 537
10.5 Reclosers and Fuses 541
10.6 Directional Relays 545
10.7 Protection of Two-Source System with Directional Relays 546

10.8 Zones of Protection 547
10.9 Line Protection with Impedance (Distance) Relays 551
10.10 Di¤erential Relays 557
10.11 Bus Protection with Di¤erential Relays 559
10.12 Transformer Protection with Di¤erential Relays 560
10.13 Pilot Relaying 565
10.14 Digital Relaying 566
CHAPTER 11
Transient Stability 579
Case Study: Real-Time Dynamic Security Assessment 581
11.1 The Swing Equation 590
11.2 Simplified Synchronous Machine Model and System
Equivalents 596
11.3 The Equal-Area Criterion 598
11.4 Numerical Integration of the Swing Equation 608
11.5 Multimachine Stability 613
11.6 A Two-Axis Synchronous Machine Model 621
11.7 Wind Turbine Machine Models 625
11.8 Design Methods for Improving Transient Stability 632
CHAPTER 12
Power System Controls 639
Case Study: Overcoming Restoration Challenges Associated
with Major Power System Disturbances 642
12.1 Generator-Voltage Control 652
12.2 Turbine-Governor Control 657
12.3 Load-Frequency Control 663
12.4 Economic Dispatch 667
12.5 Optimal Power Flow 680
CHAPTER 13
Transmission Lines: Transient Operation 690

Case Study: VariSTAR
8
Type AZE Surge Arresters 691
Case Study: Change in the Air 695
13.1 Traveling Waves on Single-Phase Lossless Lines 707
13.2 Boundary Conditions for Single-Phase Lossless Lines 710
x
CONTENTS
13.3 Bewley Lattice Diagram 719
13.4 Discrete-Time Models of Single-Phase Lossless Lines
and Lumped RLC Elements 724
13.5 Lossy Lines 731
13.6 Multiconductor Lines 735
13.7 Power System Overvoltages 738
13.8 Insulation Coordination 745
CHAPTER 14
POWER DISTRIBUTION 757
Case Study: The Path of the Smart Grid 759
14.1 Introduction to Distribution 770
14.2 Primary Distribution 772
14.3 Secondary Distribution 780
14.4 Transformers in Distribution Systems 785
14.5 Shunt Capacitors in Distribution Systems 795
14.6 Distribution Software 800
14.7 Distribution Reliability 801
14.8 Distribution Automation 804
14.9 Smart Grids 807
Appendix 814
Index 818
CONTENTS xi

PREFACE TO THE SI EDITION
This edition of Power System Analysis and Design has been adapted to incor-
porate the International System of Units (Le Syste
`
me International d’Unite
´
s
or SI) throughout the book.
LE SYSTE
`
ME INTERNATIONAL D’UNITE
´
S
The United States Customary System (USCS) of units uses FPS (foot–
pound–second) units (also called English or Imperial units). SI units are pri-
marily the units of the MKS (meter–kilogram–second) system. However,
CGS (centimeter–gram–second) units are often accepted as SI units, espe-
cially in textbooks.
USING SI UNITS IN THIS BOOK
In this book, we have used both MKS and CGS units. USCS units or FPS
units used in the US Edition of the book have been converted to SI units
throughout the text and proble ms. However, in case of data source d from
handbooks, government standards, and product manuals, it is not only ex-
tremely di‰cult to convert all values to SI, it also encroaches upon the intel-
lectual property of the source. Also, some quantities such as the ASTM grain
size number and Jominy distances are generally computed in FPS units and
would lose their relevance if converted to SI. Some data in figures, tables, ex-
amples, and references, therefore, remains in FPS units. For readers unfamil-
iar with the relationship between the FPS and the SI systems, conversion ta-
bles have been provided inside the front and back covers of the book.

To solve problems that require the use of sourced data, the sourced
values can be converted from FPS units to SI units just before they are to be
used in a calculation. To obtain standardized quantities and manufacturers’
data in SI units, the readers may contact the ap propriate government agencies
or authorit ies in t heir countries/regions.
INSTRUCTOR RESOURCES
A Printed Instructor’s Solution Manual in SI units is available on request. An
electronic version of the Instructor’s Solutions Manual, and PowerP oint
slides of the figures from the SI text are available through http://login.
cengage.com.
The readers’ feedback on this SI Edition will be highly appreciated and
will help us improve subsequent editions.
The Publishers
xii
PREFACE
The objective of this book is to present methods of power system analysis and
design, particularly with the aid of a personal computer, in su‰cient depth
to give the student the basic theory at the undergraduate level. The approach
is designed to develop students’ thinking processes, enabling them to reach a
sound understanding of a broad range of topics related to power system
engineering, while motivating their interest in the electrical power industry.
Because we believe that fundamental physical concepts underlie creative
engineering and form the most valuable and permanent part of an engineering
education, we highlight physical concepts while giving due attention to math-
ematical techniques. Both theory and modeling are developed from simple be-
ginnings so that they can be readily extended to new and complex situations.
This edition of the text features new Chapter 14 entitled, Power Distribu-
tion. During the last decade, major improvements in distribution reliability
have come through automated distribution and more recently through the
introduction of ‘‘smart grids.’’ Chapter 14 introduces the basic features of pri-

mary and secondary distribution systems as well as basic distribution compo-
nents including distribution substation transformers, distribution transformers,
and shunt capacitors. We list some of the major distribution software vendors
followed by an introduction to distribution reliability, distribution automation,
and smart grids.
This edition also features the following: (1) wind-energy systems model-
ing in the chapter on transient stability; (2) discussion of reactive/pitch control
of wind generation in the chapter on powers system controls; (3) updated case
studies for nine chapters along with four case studies from the previous edition
describing present-day, practical applications and new technologies; (4) an
updated PowerWorld Simulator package; and (5) updated problems at the end
of chapters.
One of the most challenging aspects of engineering education is giving
students an intuitive feel for the systems they are studying. Engineering sys-
tems are, for the most part, complex. While paper-and-pencil exercises can
be quite useful for highlighting the fundamentals, they often fall short in
imparting the desired intuitive insight. To help provide this insight, the book
uses PowerWorld Simulator to integrate computer-based examples, problems,
and design projects throughout the text.
PowerWorld Simulator was originally developed at the University of
Illinois at Urbana–Champaign to teach the basics of power systems to
nontechnical people involved in the electricity industry, with version 1.0 in-
troduced in June 1994. The program’s interactive and graphical design made
xiii
it an immediate hit as an educational tool, but a funny thing happened—its
interactive and graphical design also appealed to engineers doing analysis of
real power systems. To meet the needs of a growing group of users,
PowerWorld Simulator was commercialized in 1996 by the formation of
PowerWorld Corporation. Thus while retaining its appeal for education, over
the years PowerWorld Simulator has evolved into a top-notch analysis pack-

age, able to handle power systems of any size. PowerWorld Simulator is now
used throughout the power industry, with a range of users encompassing uni-
versities, utilities of all sizes, government regulators, power marketers, and
consulting firms.
In integrating PowerWorld Simulator with the text, our design philoso-
phy has been to use the sof tware to extend, rather than replace, the fully
worked examples provided in previous editions. Therefore, except when the
problem size makes it impractical, each PowerWorld Simulator example in-
cludes a fully worked hand solution of the problem along with a PowerWorld
Simulator case. This format allows students to simultaneously see the details
of how a problem is solved and a computer implementation of the solution.
The added benefit from PowerWorld Simulator is its ability to easily extend
the example. Through its interactive design, students can quickly vary example
parameters and immediately see the impact such changes have on the
solution. By reworking the examples with the new parameters, students get im-
mediate feedback on whether they understand the solution process. The inter-
active and visual design of PowerWorld Simulator also makes it an excellent
tool for instructors to use for in-class demonstrations. With numerous exam-
ples utilizing PowerWorld Simulator instructors can easily demonstrate many
of the text topics. Additional PowerWorld Simulator functionality is in-
troduced in the text problems and design projects.
The text is intended to be fully covered in a two- semester or three-
quarter course o¤ered to seniors and first-year graduate students. The orga-
nization of chapters and ind ividual sections is flexible enough to give the
instructor su‰cient latitude in choosing topics to cover, especially in a one-
semester course. The text is supported by an ample number of worked exam-
ples covering most of the theoretical points raised. The many problems to be
worked with a calculator as well as problems to be worked using a personal
computer have been expanded in this edition .
As background for this course, it is assumed that students have had

courses in electric network theory (including transient analysis) and ordinary
di¤erential equations and have bee n exposed to linear systems, matrix algebra,
and computer programming. In addition, it would be helpful, but not neces-
sary, to have had an electric machines course.
After an introduction to the history of electric power systems along
with present and future trends, Chapter 2 on fundamentals orients the students
to the terminology and serves as a brief review. The chapter reviews phasor
concepts, power, and single-phase as well as three-phase circuits.
Chapters 3 through 6 examine power transformers, transmission-line
parameters, steady-state operat ion of transmission lines, and power flows
xiv
PREFACE
including the Newton–Raphson method. These chapters provide a basic
understanding of power systems under balanced three-phase, steady-state,
normal operating conditions.
Chapters 7 through 10, which cover symmetrical faults, symmetrical
components, unsymmetrical faults, and system protection, come under the
general heading of power system short-circuit protection. Chapter 11 (pre-
viously Chapter 13) examines transient stability, which includes the swing
equation, the equal-area criterion, and multi-machine stability with modeling
of wind-energy systems as a new feature. Chapter 12 (previously Chapter 11)
covers power system controls, including turbine-generator controls, load-
frequency control, economic dispatch, and optimal power flow, with reactive/
pitch control of wind generation as a new feature. Chapter 13 (previously
Chapter 12) examines transient operation of transmission lines including
power system overvoltages and surge protection. The final and new Chapter 14
introduces power distribution.
ADDITIONAL RESOURCES
Companion websites for this book are available for both students and in-
structors. These websites provide useful links, figures, and other support ma-

terial. The Student Companion Site includes a link to download the free stu-
dent version of PowerWorld. The Instructor Companion Site includes access
to the solutions manual and PowerPoint slides. Through the Instructor Com-
panion Site, instructors can also request access to additional support mate-
rial, including a printed solutions manual.
To access the support material described here along with all additional
course materials, please visit www.cengagebrain.com. At the cengage-
brain.com home page, search for the ISBN of your title (from the back cover
of your book) using the search box at the top of the page. This will take you
to the product page where these resources can be found.
ACKNOWLEDGMENTS
The material in this text was gradually developed to meet the needs of classes
taught at universities in the United States and abroad over the past 30 years.
The original 13 chapters were written by the first author, J. Duncan Glover,
Failure Electrical LLC, who is indebted to many people who helped during
the planning and writing of this book. The profound influence of earlier texts
written on power systems, particularly by W. D. Stevenson, Jr., and the de-
velopments made by various outstanding engineers are gratefully acknowl-
edged. Details of sources can onl y be made through references at the end of
each cha pter, as they are otherwise too numerous to mention.
Chapter 14 (Power Distribution) was a collaborative e¤ort between
Dr. Glover (Sections 14.1–14.7) and Co-author Thomas J. Overbye (Sections
14.8 & 14.9). Professor Overbye, University of Illinois at Urbana-Champaign ,
PREFACE xv
updated Chapter 6 (Power Flows), Chapter 11 (Transient Stability), and
Chapter 12 (Power System Controls) for this edition of the text. He also pro-
vided the examples and problems using PowerWorld Simulator as well as
three design projects. Co-author Mulukutla Sarma, Northeastern University,
contributed to end-of-chapter multiple-choice questions and problems.
We commend the following Cengage Learning professionals: Chris

Shortt, Publisher, Global Engineering; Hilda Gowans, Senior Developmental
Editor; Swati Meherishi, Acquisitions Editor; and Kristiina Paul, Permissions
Researcher; as well as Rose Kernan of RPK Editorial Services, lnc., for their
broad k nowledge, skills, an d ingenuity in publishing this edition.
The reviewers for the fifth edition are as follows: Thomas L. Baldwin,
Florida State University ; Ali Emadi, Illinois I nstitute of Technology; R eza Iravani,
University of Toronto ; S urya Santoso, University of Texas at A ustin; A li Shaban,
California Polytechnic State University, San Luis Obispo; a nd Dennis O. Wiitanen,
Michigan Technological University, and Hamid Ja¤ari, Danvers Electric.
Substantial contributions to prior editions of this text were made by a
number of invaluable reviewers, as follows:
Fourth Edition: Robert C. Degene¤, Rensselaer Polytechnic Institute; Venkata Dina-
vahi, University of Alberta; Richard G. Far mer, Arizona State University;
Steven M. Hietpas, South Dakota State University; M. Hash em Nehrir,
Montana State University; Anil Pahwa, Kansas State University; and Ghadir
Radman, Tennessee Technical University.
Third Edition: Sohrab Asgarpoor, University of Nebraska–Lincoln; Mariesa L. Crow,
University of Missouri–Rolla; Ilya Y. Grinberg, State University of New
York, College at Bu¤alo; Iqbal Husain, The University of Akron;W.H.
Kersting, New Mexico State University; John A. Palmer, Colorado School
of Mines; Satish J. Ranada, New M exico State University; and Shyama C.
Tandon, California Polytechnic State University.
Second Edition: Max D. Anderson, University of Missouri–Rolla; Sohrab Asgarpoor,
University of Nebraska–Lincoln; Kaveh Ashenayi, University of Tulsa;
Richard D. Christie, Jr., University of Washington; Mariesa L. Crow, Univer-
sity of Missouri–Rolla; Richard G. Farmer, Arizona State University; Saul
Goldberg, California Polytechnic University; Cli¤ord H. Grigg, Rose-Hulman
Institute of Technology; Howard B. Hamilton, University of Pittsburgh;
Leo Holzenthal, Jr., University of New Orleans; Walid Hubbi, New Jersey
Institute of Technology; Charles W. Isherwood, University of Massachusetts–

Dartmouth;
W. H. Kersting, New Mexico State University; Wayne E.
Knabach, South Dakota State University; Pierre-Jean Lagace, IREQ Institut
de Reserche d’Hydro–Quebec; James T. Lancaster, Alfred University; Kwang
Y. Lee, Pennsylvania State University; Mohsen Lotfalian, University of Ev-
ansville; Rene B. Marxheimer, San Francisco State University, Lamine Mili,
Virginia Polytechnic Institute and State University; Osama A. Mohammed,
Florida International University; Cli¤ord C. Mosher, Washington State Uni-
versity, Anil Pahwa, Kansas State University; M. A. Pai, University of Illinois
xvi
PREFACE
at Urbana–Champaign; R. Ramakumar, Oklahoma State University; Teodoro
C. Robles, Milwaukee School of Engineering, Ronald G. Schultz, Cleveland
State University; Stephen A. Sebo, Ohio State University; Raymond Shoults,
University of Texas at Arlington, Richard D. Shultz, University of Wisconsin
at Platteville; Charles Slivinsky, University of Missouri–Columbia; John P.
Stahl, Ohio Northern University; E. K. Stanek, University of Missouri–Rolla;
Robert D. Strattan, University of Tulsa; Tian-Shen Tang, Texas A&M
University–Kingsville; S. S. Venkata, University of Washington; Francis M.
Wells, Vanderbilt University; Bill Wieserman, University of Pennsylvania–
Johnstown; Stephen Williams, U.S. Naval Postgraduate School; and Salah M.
Yousif, California State University–Sacr amento.
First Edition: Frederick C. Brockhurst, Rose-Hulman Institute of Technology; Bell A.
Cogbill. Northeastern University; Saul Goldberg, California Polytechnic State
University; Mack Grady, University of Texas at Austin; Leonard F. Grigsby,
Auburn University; Howard Hamilton, University of Pittsburgh; William
F. Horton, California Polytechnic Sta te University; W. H. Kersting, New
Mexico State University; John Pavlat, Iowa State University; R. Ramakumar,
Oklahoma State University; B. Don Russell, Texas A&M; Sheppard Salon,
Rensselaer Polytechnic Institute; Stephen A. Sebo, Ohio State University; and

Dennis O. Wiitanen, Michigan Technological University.
In conclusion, the objective in writing this text and the accompanying
software package will have been fulfilled if the book is considered to be
student-oriented, comprehensive, and up to date, with consistent notation
and necessary detailed explanation at the level for which it is intend ed.
J. Duncan Glover
Mulukutla S. Sarma
Thomas J. Overbye
PREFACE
xvii
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xix
LIST OF SYMBOLS, UNITS, AND NOTATION
Symbol Description
a operator 1
120

a
t
transformer turns ratio
A area
A transmission line parameter
A symmetrical components
transformation matrix
B loss coe‰cient
B frequency bias constant
B phasor magnetic flux density
B transmission line parameter
C capacitance
C transmission line parameter

D distance
D transmission line parameter
E phasor source voltage
E phasor electric field strength
f frequency
G conductance
G conductance matrix
H normalized inertia constant
H phasor magnetic field intensity
i ðtÞ instantaneous current
I current magnitude (rms unless
otherwise indicated)
I phasor current
I vector of phasor currents
j operator 1
90

J moment of inertia
l length
l length
L inductance
L inductance matrix
N number (of buses, lines, turns, etc.)
p.f. power factor
pðtÞ instantaneous power
Symbol Description
P real power
q charge
Q reactive power
r radius

R resistance
R turbine-governor regulation
constant
R resistance matrix
s Laplace operator
S apparent power
S complex power
t time
T period
T temperature
T torque
vðtÞ instantaneous voltage
V voltage magnitude (rms unless
otherwise indicated)
V phasor voltage
V vector of phasor voltages
X reactance
X reactance matrix
Y phasor admittance
Y admittance matrix
Z phasor impedance
Z impedance matrix
a angular acceleration
a transformer phase shift angle
b current angle
b area frequency response
characteristic
d voltage angle
d torque angle
e permittivity

G reflection or refraction coe‰cient
Symbol Description
l magnetic flux linkage
l penalty factor
F magnetic flux
r resistivity
t time in cycles
t transmission line transit time
Symbol Description
y impedance angle
y angular position
m permeability
n velocity of propagation
o radian frequency
SI Units
A ampere
C coulomb
F farad
H henry
Hz hertz
J joule
kg kilogram
m meter
N newton
rad radian
s second
S siemen
VA voltampere
var voltampere reactive
W watt

Wb weber
W ohm
English Units
BTU British thermal unit
cmil circular mil
ft foot
hp horsepower
in inch
mi mile
Notation
Lowercase letters such as v(t) and i(t) indicate instantaneous values.
Uppercase letters such as V and I indicate rms values.
Uppercase letters in italic such as V and I indicate rms phasors.
Matrices and vectors with real components such as R and I are indicated by
boldface type.
Matrices and vectors with complex components such as Z and I are indicated
by boldface italic type.
Superscript T denotes vector or matrix transpose.
Asterisk (*) denotes complex conjugate.
9 indicates the end of an example and continuation of text.
PW
highlights problems that utilize PowerWorld Simulator.
xx
LIST OF SYMBOLS, UNITS, AND NOTATION
1
INTRODUCTION
E
lectrical engineers are concerned with every step in the process of genera-
tion, transmission, distributio n, and utilization of electrical energy. The elec-
tric utility industry is probably the largest and most complex industry in the

world. The electrical engineer who works in that industry will encounter
challenging problems in designing future power systems to deliver increasing
amounts of electrical energy in a safe, clean, and economical manner.
The objectives of this chapter are to review briefly the history of the
electric utility industry, to discuss present and future trends in electric power
systems, to describe the restructuring of the electric utility industry, and to
introduce PowerWorld Simulator—a power system analysis and simulation
software package.
1
1300 MW coal-fired power
plant (Courtesy of
American Electric Power
Company)
CASE STUDY The following article describes the restructuring of the electric utility industry that has
been taking place in the United States and the impacts on an aging transmission
infrastructure. Independent power producers, increased competition in the generation
sector, and open access for generators to the U.S. transmission system have changed the
way the transmission system is utilized. The need for investment in new transmission and
transmission technologies, for further refinements in restructuring, and for training and
education systems to replenish the workforce are discussed [8].
The Future Beckons: Will the Electric
Power Industry Heed the Call?
CHRISTOPHER E. ROOT
Over the last four decades, the U.S. electric power
industry has undergone unprecedented change. In
the 1960s, regulated utilities gener ated and deliv-
ered power within a localized service area. The
decade was marked by high load growth and mod-
est price stability. This stood in sharp contrast to
the wild increases in the price of fuel oil, focus on

energy conservation, and slow growth of the 1970s.
Utilities quickly put the brakes on generation ex-
pansion projects, switched to coal or other nonoil
fuel sources, and significa ntly cut back on the ex-
pansion of their networks as load growth slowed to
a crawl. During the 1980s, the economy in many
regions of the country began to rebound. The
1980s also brought the emergence of independent
power producers and the deregulation of the natu-
ral gas wholesale markets and pipelines. These de-
velopments resulted in a significant increase in nat-
ural gas transmission into the northeastern United
States and in the use of natural gas as the preferred
fuel for new generating plants.
During the last ten years, the industry in many
areas of the United States has seen increased com-
petition in the generation sector and a fundamental
shift in the role of the nation’s electric transmission
system, with the 1996 enactment of the Federal
Energy Regulatory Commission (FERC) Order No.
888, which mandated open access for generators to
the nation’s transmission system. And while prices
for distribution and transmission of electricity re-
mained regulated, unregulated energy commodity
markets have developed in several regions. FERC
has supported these changes with rulings leading
to the formation of independent system oper-
ators (ISOs) and regional transmission organ-
izations (RTOs) to administer the electricity mar-
kets in several regions of the United States,

including New England, New York, the Mid-Atlantic,
the Midwest, and California.
The transmission system originally was built to
deliver power from a utility’s generator across town
to its distribution company. Today, the transmission
system is being used to deliver power across states
or entire regions. As market forces increasingly
determine the location of generation sources, the
transmission grid is being asked to play an even
more important role in markets and the reliability
of the system. In areas where markets have been
restructured, customers have begun to see signifi-
cant benefits. But full delivery of restructuring’s
benefits is being impeded by an inadequate, under-
invested transmission system.
If the last 30 years are any indication, the struc-
ture of the industry and the increasing demands
placed on the nation’s transmission infrastructure
and the people who operate and manage it are
likely to continue unabated. In order to meet
the challenges of the future, to continue to maintain
the stable, reliable, and efficient system we have
known for more than a centur y and to support the
(‘‘The Future Beckons,’’ Christopher E. Root. > 2006 IEEE.
Reprinted, with permission, from Supplement to IEEE Power
& Energy (May/June 2006) pg. 58–65)
2 CHAPTER 1 INTRODUCTION
continued development of efficient competitive
markets, U.S. industry leaders must address three
significant issues:

.
an aging transmission system suffering from
substantial underinvestment, which is exacer-
bated by an out-of-date industry structure
.
the need for a regulatory framework that will
spur independent investment, ownership, and
management of the nation’s grid
.
an aging workforce and the need for a suc-
cession plan to ensure the existence of the
next generation of technical expertise in the
industry.
ARE WE SPENDING ENOUGH?
In areas that have restructured power markets,
substantial benefits ha v e been delivered to customers
in the form of lower prices, greater supplier choice,
and environmental benefits, largely due to the de-
velopment and operation of new, cleaner genera-
tion. There is, however, a growing recognition that
the delivery of the full value of restructuring to cus-
tomers has been stalled by an inadequate transmis-
sion system that was not designed for the new de-
mands being placed on it. In fact, investment in the
nation’s electricity infrastructure has been declining
for decades. Transmission investment has been falling
for a quarter century at an average rate of almost
US$50 million a year (in constant 2003 U.S. dollars),
though there has been a small upturn in the last few
years. Transmission investment has not kept up with

load growth or generation investment in recent
years, nor has it been sufficiently expanded to ac-
commodate the advent of regional power markets
(see Figure 1).
CASE STUDY 3
Figure 1
Annual transmission investments by investor-owned utilities, 1975–2003 (Source: Eric Hirst, ‘‘U.S. Transmission
Capacity: Present Status and Future Prospects,’’ 2004. Graph used with permission from the Edison Electric Institute,
2004. All rights reserved)