Preface ...................................................... xiii
Acknowledgments ................................................ xv
About the Author ............................................. xvii
Chapter 1 Overview ............................................. 1
1.1 Introduction ............................................... 1
1.2 Why Renewable Energy ....................................... 1
1.3 Wind Energy ................................................ 2
1.4 Advantages and Disadvantages of Wind-Generated
Electricity ................................................ 2
1.4.1 A Renewable Nonpolluting Resource ................... 2
1.4.2 Cost Issues ......................................... 3
1.4.3 Environmental Concerns .............................. 3
1.4.4 Supply and Transport Issues ......................... 3
1.5 Worldwide Status of Wind Energy ............................ 3
1.5.1 Europe .............................................. 4
1.5.2 Germany ............................................. 4
1.5.3 Spain ............................................... 4
1.5.4 Italy ............................................... 5
1.5.5 France .............................................. 5
1.5.6 United Kingdom ...................................... 5
1.5.7 European Union ...................................... 5
1.5.8 North America ....................................... 6
1.5.8.1 United States .............................. 6
1.5.8.2 Canada ..................................... 6
1.5.9 Asia ................................................ 7
1.5.9.1 China ...................................... 7
1.5.9.2 India ...................................... 7
1.5.9.3 Japan ...................................... 7
1.5.10 Pacific ............................................. 8
1.5.10.1 Australia .................................. 8
1.5.10.2 New Zealand ................................ 8
1.5.11 Latin America ....................................... 8
1.5.11.1 Brazil ..................................... 8
1.5.11.2 Mexican Power Generation System ............ 9
1.5.12 Africa and Middle East .............................. 9
1.5.12.1 130 MW Installed in Africa and Middle
East ....................................... 9
1.6 Aim and Scope of the Book .................................. 9
References ................................................ 13
Chapter 2 Wind Energy Conversion System ....................... 17
2.1 Introduction .............................................. 17
2.2 Fundamental Concept ....................................... 17
2.3 Wind Energy Technology .................................... 17
2.4 Basic Components of a Wind Turbine System ................. 19
2.5 Types of Wind Turbines .................................... 20
2.5.1 Wind Turbines Based on Axes ........................ 20
2.5.1.1 Vertical Axis Wind Turbines ............... 21
2.5.1.2 Horizontal Axis Wind Turbines ............. 22
2.5.2 Wind Turbine Power Scales .......................... 23
2.5.3 Wind Turbine Installation Location ................. 24
2.6 Modeling of Wind Turbines ................................. 25
2.6.1 Power Output from an Ideal Turbine ................. 25
2.6.2 Power Output from Practical Turbines ............... 28
2.6.2.1 Wind Turbine Design Speed ................. 30
2.6.2.2 Pitch Mechanism ........................... 30
2.6.2.3 Effect of Wind Shear and Tower Shadow ..... 31
2.6.2.4 Wind Shear ................................ 31
2.6.2.5 Tower Shadow .............................. 32
2.7 Chapter Summary ........................................... 32
References ..................................................... 32
Chapter 3 Electric Machines and Power Systems ................. 37
3.1 Introduction .............................................. 37
3.2 DC Machines ............................................... 37
3.3 AC Machines ............................................... 39
3.3.1 Synchronous Machines ............................... 39
3.3.1.1 Principle of Cylindrical-Rotor
Synchronous Generators .................... 41
3.3.1.2 Automatic Voltage Regulator System ........ 43
3.3.1.3 Governor Control System ................... 43
3.3.1.4 Power System Stabilizer ................... 44
3.3.1.5 Operating Principle of Synchronous
Motors .................................... 44
3.3.1.6 Permanent Magnet Synchronous Generator .... 45
3.3.1.7 Multimass Shaft System of Synchronous
Generator ................................. 46
3.3.2 Asynchronous Machines .............................. 46
3.3.2.1 Synchronous Speed ......................... 48
3.3.2.2 Slip ...................................... 48
3.3.2.3 Induction Generator or Asynchronous
Generator ................................. 49
3.3.3 Synchronous Reluctance Machine ..................... 51
3.3.4 Transformer ........................................ 53
3.3.4.1 Basic Principles .......................... 53
3.3.4.2 Induction Law ............................. 54
3.3.4.3 Ideal Power Equation ...................... 55
3.3.4.4 Detailed Operation ........................ 56
3.4 Electrical Power Systems .................................. 59
3.4.1 Conventional Power Generation ...................... 60
3.4.2 Electric Power Transmission ........................ 61
3.4.2.1 Line Parameters for Overhead
Transmission Line ......................... 63
3.4.3 Electric Power Distribution ........................ 63
3.4.4 Power System Analysis .............................. 64
3.4.5 Power Flow Study ................................... 65
3.4.6 Per-Unit System and Base Quantities ................ 66
3.4.6.1 Change of Bases ........................... 67
3.4.6.2 Per-Unit and Percent Admittance ........... 68
3.4.7 Faults in Power Systems ............................ 68
3.4.7.1 Transient Fault ........................... 69
3.4.7.2 Persistent Fault .......................... 69
3.4.7.3 Symmetrical Fault ......................... 69
3.4.7.4 Asymmetrical Fault ........................ 70
3.4.7.5 Analysis .................................. 70
3.4.7.6 Detecting and Locating Faults ............. 71
3.4.8 Power System Stability ............................. 72
3.4.8.1 Classification of Stability ............... 73
3.4.9 Circuit Breakers ................................... 80
3.4.9.1 Operation ................................. 80
3.4.9.2 Arc Interruption .......................... 81
3.4.9.3 Short-Circuit Current ..................... 82
3.4.9.4 Types of Circuit Breakers ................. 83
3.4.10 Power System Control ............................... 87
3.4.10.1 Active Power-Frequency Control ............ 87
3.4.10.2 Reactive Power-Voltage Control ............ 88
3.4.10.3 Methods of Voltage Control ................ 88
3.4.10.4 Infinite Bus Concept ...................... 89
3.5 Power Quality ............................................. 89
3.6 Chapter Summary ........................................... 91
References ..................................................... 91
Chapter 4 Power Electronics ................................... 95
4.1 Introduction .............................................. 95
4.2 Power Devices ............................................. 95
4.3 Rectifier ................................................. 96
4.4 Inverter .................................................. 96
4.5 Chopper .................................................. 100
4.6 Cycloconverter ........................................... 104
4.7 Pulse Width Modulation Scheme ............................ 104
4.8 PWM VSC .................................................. 107
4.9 Current Source Inverter .................................. 107
4.10 Chapter Summary .......................................... 110
References .................................................... 110
Chapter 5 Wind Generators .................................... 113
5.1 Introduction ............................................. 113
5.2 Fixed-Speed Wind Energy Conversion Systems ............... 113
5.3 Variable-Speed Wind Energy Conversion Systems ............ 114
5.4 Wind Generators .......................................... 115
5.4.1 Synchronous Generators ............................ 117
5.4.2 Induction Generators .............................. 117
5.5 Wind Generator Characteristics ........................... 118
5.6 Maximum Power Point Tracking System ...................... 121
5.7 WG Total Efficiency Calculation .......................... 123
5.7.1 Outline of the Calculation Method ................. 123
5.7.2 Equations for Analysis ............................ 125
5.7.2.1 Wind Turbine Power ....................... 125
5.7.2.2 Generator Input .......................... 125
5.7.2.3 Copper Losses and Iron Loss .............. 126
5.7.2.4 Bearing Loss, Windage Loss, and Stray
Load Loss ................................ 126
5.7.2.5 Gearbox Loss ............................. 127
5.7.3 Calculation Method ................................ 127
5.7.4 Simulation Results ................................ 130
5.7.5 Simulation Result with Transient Phenomenon
Considered ........................................ 132
5.7.6 Efficiency Calculation Using a Probability
Density Function .................................. 134
5.8 Chapter Summary .......................................... 135
References .................................................... 137
Chapter 6 Wind Generator Grid Integration Issues ............. 141
6.1 Introduction ............................................. 141
6.2 Transient Stability and Power Quality Problems ........... 141
6.3 Variability of Wind Power ................................ 142
6.4 Power, Frequency, and Voltage Fluctuations Due to
Random Wind Speed Variation .............................. 142
6.5 Grid Connection Requirements ............................. 143
6.5.1 Islanding and Auto Reclosure ...................... 147
6.5.2 Other Issues ...................................... 148
6.5.2.1 Ferroresonance ........................... 148
6.5.2.2 Grounding ................................ 148
6.6 Design and Operation of Power Systems .................... 149
6.7 Storage Options .......................................... 150
6.8 Grid Infrastructure ...................................... 150
6.9 Wind Power's Contribution to System Adequacy ............. 151
6.10 Chapter Summary .......................................... 151
References .................................................... 151
Chapter 7 Solutions for Power Quality Issues of Wind
Generator Systems ............................................. 155
7.1 Introduction ............................................. 155
7.2 Various Energy Storage Systems ........................... 156
7.2.1 Superconducting Magnetic Energy Storage ........... 156
7.2.2 Battery Energy Storage Systems .................... 159
7.2.3 Advanced Capacitors ............................... 161
7.2.4 Flywheel Energy Storage (FES) ..................... 163
7.2.5 Pumped Hydroelectric Energy Storage ............... 165
7.2.6 Flow Batteries .................................... 165
7.2.7 Compressed Air Energy Storage ..................... 167
7.2.8 Thermoelectric Energy Storage ..................... 167
7.2.9 Hybrid Energy Storage Systems ..................... 168
7.3 Energy Storage Systems Compared .......................... 168
7.4 Using SMES to Minimize Fluctuations in Power,
Frequency, and Voltage of Wind Generator Systems ......... 168
7.4.1 Method of Calculating Power System Frequency ...... 173
7.4.2 Simulation Results and Discussions ................ 174
7.4.2.1 Effectiveness of SMES Systems on
Minimizing Wind Generator Power,
Frequency, and Voltage Fluctuations ...... 174
7.4.2.2 Comparison among Energy Capacities of
SMES Systems to Minimize Wind Generator
Power, Frequency, and Voltage
Fluctuations ............................. 175
7.4.3 SMES Power and Energy Ratings ..................... 178
7.5 Power Quality Improvement Using a Flywheel Energy
Storage System ........................................... 189
7.5.1 DC Bus Microgrid System ........................... 193
7.5.2 Volt/Hertz Control ................................ 194
7.5.3 Microgrid System Operation ........................ 195
7.5.4 Control of Flywheel Energy Storage System ......... 196
7.5.5 Stability Consideration ........................... 197
7.6 Constant Power Control of DFIG Wind Turbines with
Supercapacitor Energy Storage ............................ 198
7.6.1 Control of Individual DFIG Wind Turbines .......... 199
7.6.2 Control of the RSC ................................ 199
7.6.3 Control of the GSC ................................ 200
7.6.4 Configuration and Control of the ESS .............. 201
7.6.5 Wind Turbine Blade Pitch Control .................. 202
7.6.6 Wind Farm Supervisory Control ..................... 203
7.7 Output Power Leveling of Wind Generator Systems by
Pitch Angle Control ...................................... 203
7.8 Chapter Summary .......................................... 207
References .................................................... 208
Chapter 8 Solutions for Transient Stability Issues of
Fixed-Speed Wind Generator Systems ............................ 213
8.1 Introduction ............................................. 213
8.2 Model System ............................................. 214
8.3 Pitch Control Method ..................................... 215
8.4 Superconducting Magnetic Energy Storage Method ........... 216
8.4.1 PWM Voltage Source Converter ...................... 217
8.4.2 Two-Quadrant DC-to-DC Chopper ..................... 217
8.5 Static Synchronous Compensator (STATCOM) Method .......... 218
8.6 Braking Resistor Method .................................. 220
8.7 Superconducting Fault Current Limiter Method ............. 221
8.8 Stabilization Methods Compared ........................... 221
8.8.1 Performance Analysis .............................. 222
8.8.2 Control Structure Analysis ........................ 228
8.8.3 Cost Analysis ..................................... 228
8.8.4 Overall Comparison ................................ 228
8.9 Chapter Summary .......................................... 231
References .................................................... 231
Chapter 9 Fault Ride-Through Capability of Variable-Speed
Wind Generator Systems ........................................ 235
9.1 Introduction ............................................. 235
9.2 Doubly Fed Induction Generator Systems ................... 235
9.2.1 Rotor Side Converter .............................. 237
9.2.2 Grid Side Converter ............................... 238
9.3 Wound Field Synchronous Generator Systems ................ 240
9.3.1 Speed Controller .................................. 242
9.3.2 Pitch Controller .................................. 243
9.3.3 Excitation Controller ............................. 244
9.3.4 Grid Side Inverter Controller ..................... 244
9.4 Permanent Magnet Synchronous Generator Systems ........... 245
9.4.1 Control of Back-to-Back Converters ................ 247
9.4.2 Control of the ESS ................................ 248
9.4.3 Rating of the ESS ................................. 249
9.4.4 Design Example for the ESS ........................ 250
9.5 Switched Reluctance Generator System ..................... 251
9.5.1 SRG Operation ..................................... 252
9.6 Chapter Summary .......................................... 254
References .................................................... 254
Index ......................................................... 257
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