PREFACE ........................................................ xi
ACKNOWLEDGMENTS .............................................. xiii
CHAPTER 1 INTRODUCTION ......................................... 1
CHAPTER 2 SOURCES OF ENERGY ..................................... 6
2.1 Wind Power ................................................. 7
2.1.1 Status .............................................. 7
2.1.2 Properties .......................................... 7
2.1.3 Variations in Wind Speed ............................ 8
2.1.4 Variations in Production Capacity .................. 10
2.1.5 The Weibull Distribution of Wind Speed ............. 20
2.1.6 Power Distribution as a Function of the Wind
Speed .............................................. 22
2.1.7 Distribution of the Power Production ............... 26
2.1.8 Expected Energy Production ......................... 29
2.2 Solar Power ............................................... 30
2.2.1 Status ............................................. 30
2.2.2 Properties ......................................... 31
2.2.3 Space Requirements ................................. 32
2.2.4 Photovoltaics ...................................... 33
2.2.5 Location of the Sun in the Sky ..................... 35
2.2.6 Cloud Coverage ..................................... 39
2.2.7 Seasonal Variations in Production Capacity ......... 42
2.2.8 Fast Variations with Time .......................... 46
2.3 Combined Heat-and-Power ................................... 50
2.3.1 Status ............................................. 50
2.3.2 Options for Space Heating .......................... 51
2.3.3 Properties ......................................... 52
2.3.4 Variation in Production with Time .................. 53
2.3.5 Correlation Between CHP and Consumption ............ 56
2.4 Hydropower ................................................ 59
2.4.1 Properties of Large Hydro .......................... 60
2.4.2 Properties of Small Hydro .......................... 61
2.4.3 Variation with Time ................................ 61
2.5 Tidal Power ............................................... 65
2.6 Wave Power ................................................ 66
2.7 Geothermal Power .......................................... 67
2.8 Thermal Power Plants ...................................... 68
2.9 Interface with the Grid ................................... 71
2.9.1 Direct Machine Coupling with the Grid .............. 72
2.9.2 Full Power Electronics Coupling with the Grid ...... 73
2.9.3 Partial Power Electronics Coupling to the Grid ..... 75
2.9.4 Distributed Power Electronics Interface ............ 79
2.9.5 Impact of the Type of Interface on the Power
System ............................................. 80
2.9.6 Local Control of Distributed Generation ............ 81
CHAPTER 3 POWER SYSTEM PERFORMANCE
3.1 Impact of Distributed Generation on the Power System ...... 84
3.1.1 Changes Taking Place ............................... 84
3.1.2 Impact of the Changes .............................. 85
3.1.3 How Severe Is This? ................................ 86
3.2 Aims of the Power System .................................. 87
3.3 Hosting Capacity Approach ................................. 88
3.4 Power Quality ............................................. 91
3.4.1 Voltage Quality .................................... 92
3.4.2 Current Quality .................................... 92
3.4.3 Multiple Generator Tripping ........................ 93
3.5 Voltage Quality and Design of Distributed Generation ...... 95
3.5.1 Normal Operation; Variations ....................... 96
3.5.2 Normal Events ...................................... 96
3.5.3 Abnormal Events .................................... 97
3.6 Hosting Capacity Approach for Events ...................... 98
3.7 Increasing the Hosting Capacity .......................... 100
CHAPTER 4 OVERLOADING AND LOSSES
4.1 Impact of Distributed Generation ......................... 102
4.2 Overloading: Radial Distribution Networks ................ 105
4.2.1 Active Power Flow Only ............................ 105
4.2.2 Active and Reactive Power Flow .................... 108
4.2.3 Case Study 1: Constant Production ................. 109
4.2.4 Case Study 2: Wind Power .......................... 110
4.2.5 Case Study 3: Wind Power with Induction
Generators ........................................ 111
4.2.6 Case Study 4: Solar Power with a Hotel ............ 111
4.2.7 Minimum Consumption ............................... 115
4.3 Overloading: Redundancy and Meshed Operation ............. 116
4.3.1 Redundancy in Distribution Networks ............... 116
4.3.2 Meshed Operation .................................. 117
4.3.3 Redundancy in Meshed Networks ..................... 119
4.4 Losses ................................................... 122
4.4.1 Case Study 1: Constant Production ................. 124
4.4.2 Case Study 2: Wind Power .......................... 125
4.5 Increasing the Hosting Capacity .......................... 126
4.5.1 Increasing the Loadability ........................ 126
4.5.2 Building New Connections .......................... 127
4.5.3 Intertrip Schemes ................................. 127
4.5.4 Advanced Protection Schemes ....................... 128
4.5.5 'Energy Management Systems ........................ 131
4.5.6 Power Electronics Approach ........................ 133
4.5.7 Demand Control .................................... 136
4.5.8 Risk-Based Approaches ............................. 137
4.5.9 Prioritizing Renewable Energy ..................... 139
4.5.10 Dynamic Loadability ............................... 139
CHAPTER 5 VOLTAGE MAGNITUDE VARIATIONS ....................... 141
5.1 Impact of Distributed Generation ........................ 141
5.2 Voltage Margin and Hosting Capacity ...................... 144
5.2.1 Voltage Control in Distribution Systems ........... 144
5.2.2 Voltage Rise Owing to Distributed Generation ...... 146
5.2.3 Hosting Capacity .................................. 147
5.2.4 Induction Generators .............................. 149
5.2.5 Measurements to Determine the Hosting Capacity .... 150
5.2.6 Estimating the Hosting Capacity Without
Measurements ...................................... 151
5.2.7 Choosing the Overvoltage Limit .................... 153
5.2.8 Sharing the Hosting Capacity ...................... 156
5.3 Design of Distribution Feeders ........................... 156
5.3.1 Basic Design Rules ................................ 156
5.3.2 Terminology ....................................... 157
5.3.3 An Individual Generator Along a Medium-Voltage
Feeder ............................................ 158
5.3.4 Low-Voltage Feeders ............................... 163
5.3.5 Series and Shunt Compensation ..................... 166
5.4 A Numerical Approach to Voltage Variations ............... 168
5.4.1 Example for Two-stage Boosting .................... 168
5.4.2 General Expressions for Two-Stage Boosting ........ 170
5.4.3 Single-Stage Boosting ............................. 171
5.4.4 Microgeneration ................................... 171
5.5 Tap Changers with Line-Drop Compensation ................. 174
5.5.1 Transformer with One Single Feeder ................ 174
5.5.2 Adding a Generator ................................ 175
5.5.3 Calculating the Hosting Capacity .................. 177
5.5.4 Multiple Feeders from the Same Transformer ........ 178
5.6 Probabilistic Methods for Design of Distribution
Feeders .................................................. 181
5.6.1 Need for Probabilistic Methods .................... 181
5.6.2 The System Studied ................................ 181
5.6.3 Probability Density and Distribution Functions .... 182
5.6.4 Distributions of Functions of Random Variables .... 182
5.6.5 Mean and Standard Deviation ....................... 183
5.6.6 Normal Distributions .............................. 184
5.6.7 Stochastic Calculations Using Measurements ........ 185
5.6.8 Generation with Constant Production ............... 190
5.6.9 Adding Wind Power ................................. 191
5.7 Statistical Approach to Hosting Capacity ................. 192
5.8 Increasing the Hosting Capacity .......................... 197
5.8.1 New or Stronger Feeders ........................... 198
5.8.2 Alternative Methods for Voltage Control ........... 199
5.8.3 Accurate Measurement of the Voltage Magnitude
Variations ........................................ 200
5.8.4 Allowing Higher Overvoltages ...................... 201
5.8.5 Risk-Based Approach to Overvoltages ............... 202
5.8.6 Overvoltage Protection ............................ 203
5.8.7 Overvoltage Curtailment ........................... 204
5.8.8 Dynamic Voltage Control ........................... 209
5.8.9 Compensating the Generator's Voltage Variations ... 210
5.8.10 Distributed Generation with Voltage Control ....... 211
5.8.11 Coordinated Voltage Control ....................... 218
5.8.12 Increasing the Minimum Load ....................... 221
CHAPTER 6 POWER QUALITY DISTURBANCES
6.1 Impact of Distributed Generation ......................... 223
6.2 Fast Voltage Fluctuations ................................ 225
6.2.1 Fast Fluctuations in Wind Power ................... 226
6.2.2 Fast Fluctuations in Solar Power .................. 228
6.2.3 Rapid Voltage Changes ............................. 228
6.2.4 Very Short Variations ............................. 230
6.2.5 Spread of Voltage Fluctuations .................... 233
6.3 Voltage Unbalance ........................................ 237
6.3.1 Weaker Transmission System ........................ 237
6.3.2 Stronger Distribution System ...................... 238
6.3.3 Large Single-Phase Generators ..................... 240
6.3.4 Many Single-Phase Generators ...................... 242
6.4 Low-Frequency Harmonics .................................. 247
6.4.1 Wind Power: Induction Generators .................. 248
6.4.2 Generators with Power Electronics Interfaces ...... 250
6.4.3 Synchronous Generators ............................ 251
6.4.4 Measurement Example ............................... 252
6.4.5 Harmonic Resonances ............................... 254
6.4.6 Weaker Transmission Grid .......................... 266
6.4.7 Stronger Distribution Grid ........................ 267
6.5 High-Frequency Distortion ................................ 270
6.5.1 Emission by Individual Generators ................. 271
6.5.2 Grouping Below and Above 2 kHz .................... 274
6.5.3 Limits Below and Above 2 kHz ...................... 275
6.6 Voltage Dips ............................................. 278
6.6.1 Synchronous Machines: Balanced Dips ............... 279
6.6.2 Synchronous Machines: Unbalanced Dips ............. 282
6.6.3 Induction Generators and Unbalanced Dips .......... 287
6.7 Increasing the Hosting Capacity .......................... 291
6.7.1 Strengthening the Grid ............................ 292
6.7.2 Emission Limits for Generator Units ............... 292
6.7.3 Emission Limits for Other Customers ............... 293
6.7.4 Higher Disturbance Levels ......................... 294
6.7.5 Passive Harmonic Filters .......................... 296
6.7.6 Power Electronics Converters ...................... 296
6.7.7 Reducing the Number of Dips ....................... 297
6.7.8 Broadband and High-Frequency Distortion ........... 298
CHAPTER 7 PROTECTION ......................................... 299
7.1 Impact of Distributed Generation ......................... 299
7.2 Overcurrent Protection ................................... 303
7.2.1 Upstream and Downstream Faults .................... 303
7.2.2 Hosting Capacity .................................. 304
7.2.3 Fuse-Recloser Coordination ........................ 305
7.2.4 Inverse-Time Overcurrent Protection ............... 308
7.3 Calculating the Fault Currents ........................... 310
7.3.1 Upstream Faults ................................... 310
7.3.2 Downstream Faults ................................. 320
7.3.3 Induction Generators, Power Electronics, and
Motor Load ........................................ 325
7.4 Calculating the Hosting Capacity ......................... 326
7.5 Busbar Protection ........................................ 333
7.6 Excessive Fault Current .................................. 334
7.7 Generator Protection ..................................... 336
7.7.1 General Requirements .............................. 336
7.7.2 Insufficient Fault Current ........................ 337
7.7.3 Noncontrolled Island Operation .................... 340
7.7.4 Islanding Detection ............................... 342
7.7.5 Harmonic Resonance During Island Operation ........ 354
7.7.6 Protection Coordination ........................... 357
7.8 Increasing the Hosting Capacity .......................... 358
7.8.1 Dedicated Feeder .................................. 359
7.8.2 Increased Generator Impedance ..................... 360
7.8.3 Generator Tripping ................................ 360
7.8.4 Time-Current Setting .............................. 361
7.8.5 Adding an Additional Circuit Breaker .............. 362
7.8.6 Directional Protection ............................ 362
7.8.7 Differential or Distance Protection ............... 363
7.8.8 Advanced Protection Schemes ....................... 363
7.8.9 Islanding Protection .............................. 365
CHAPTER 8 TRANSMISSION SYSTEM OPERATION ...................... 367
8.1 Impact of Distributed Generation ......................... 367
8.2 Fundamentals of Transmission System Operation ............ 371
8.2.1 Operational Reserve and (N - 1) Criterion ......... 372
8.2.2 Different Types of Reserve ........................ 373
8.2.3 Automatic or Manual Secondary Control ............. 375
8.3 Frequency Control, Balancing, and Reserves ............... 376
8.3.1 The Need for Reserves ............................. 376
8.3.2 Primary Control and Reserves ...................... 377
8.3.3 Secondary Control and Reserves .................... 382
8.3.4 Tertiary Control and Reserves ..................... 389
8.3.5 Impact of Decay in Production on Reserves ......... 393
8.4 Prediction of Production and Consumption ................. 398
8.5 Restoration after a Blackout ............................. 403
8.6 Voltage Stability ........................................ 405
8.6.1 Short-Term Voltage Stability ...................... 406
8.6.2 Long-Term Voltage Stability ....................... 410
8.7 Kinetic Energy and Inertia Constant ...................... 417
8.8 Frequency Stability ...................................... 422
8.9 Angular Stability ........................................ 425
8.9.1 One Area Against the Infinite Grid ................ 425
8.9.2 Impact of Distributed Generation: Before the
Fault ............................................. 429
8.9.3 Impact of Distributed Generation: During the
Fault ............................................. 430
8.9.4 Impact of Distributed Generation: Critical
Fault-Clearing Time ............................... 431
8.9.5 Impact of Distributed Generation: After the
Fault ............................................. 435
8.9.6 Impact of Distributed Generation: Importing Area .. 436
8.10 Fault Ride-Through ....................................... 437
8.10.1 Background ........................................ 437
8.10.2 Historical Cases .................................. 439
8.10.3 Immunity Requirements ............................. 440
8.10.4 Achieving Fault Ride-Through ...................... 445
8.11 Storage .................................................. 447
8.12 HVDC and Facts ...................................... 451
8.13 Increasing the Hosting Capacity ..................... 457
8.13.1 Alternative Scheduling of Reserves ........... 457
8.13.2 Increasing the Transfer Capacity ............. 458
8.13.3 Large-Scale Energy Storage ................... 458
8.13.4 Distributed Generation as Reserve ............ 459
8.13.5 Consumption as Reserve ....................... 460
8.13.6 Requirements on Distributed Generation ....... 461
8.13.7 Reactive Power Control ....................... 461
8.13.8 Probabilistic Methods ........................ 462
8.13.9 Development of Standard Models for
Distributed Generation ....................... 464
CHAPTER 9 CONCLUSIONS ........................................ 465
|
