Power System Analysis and Design Fifth Edition By J Duncan Glover and Mulukutla S Sarma and Thomas Overbye

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Power System Analysis and Design Fifth Edition By J Duncan Glover and Mulukutla S Sarma and Thomas Overbye


Preface xiii
List of Symbols, Units, and Notation xix
CHAPTER 1 Introduction 1
Case Study: The Future Beckons: Will the Electric Power
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
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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 Conductors, 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
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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
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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: VariSTAR8 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
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
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


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 mathematical
techniques. Both theory and modeling are developed from simple beginnings
so that they can be readily extended to new and complex situations.
This edition of the text features new Chapter 14 entitled, Power Distribution.
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 primary
and secondary distribution systems as well as basic distribution components
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 modeling
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 systems
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 introduced
in June 1994. The program’s interactive and graphical design made
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 package,
able to handle power systems of any size. PowerWorld Simulator is now
used throughout the power industry, with a range of users encompassing universities,
utilities of all sizes, government regulators, power marketers, and
consulting firms.
In integrating PowerWorld Simulator with the text, our design philosophy
has been to use the software 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 includes
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 immediate
feedback on whether they understand the solution process. The interactive
and visual design of PowerWorld Simulator also makes it an excellent
tool for instructors to use for in-class demonstrations. With numerous examples
utilizing PowerWorld Simulator instructors can easily demonstrate many
of the text topics. Additional PowerWorld Simulator functionality is introduced
in the text problems and design projects.
The text is intended to be fully covered in a two-semester or threequarter
course o¤ered to seniors and first-year graduate students. The organization
of chapters and individual sections is flexible enough to give the
instructor su‰cient latitude in choosing topics to cover, especially in a onesemester
course. The text is supported by an ample number of worked examples
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 been exposed to linear systems, matrix algebra,
and computer programming. In addition, it would be helpful, but not necessary,
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 operation of transmission lines, and power flows
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 (previously
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, loadfrequency
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.