Embedded Generation

Contents......Page 6
Preface......Page 12
Contributors......Page 14
Glossary......Page 16
1.1 Embedded or dispersed generation......Page 20
1.2 Reasons for embedded generation......Page 21
1.3 Extent of embedded generation......Page 23
1.4 Issues of embedded generation......Page 28
1.5.1 Network voltage changes......Page 30
1.5.3 Power quality......Page 33
1.5.4 Protection......Page 34
1.5.5 Stability......Page 36
1.6 Economic impact of embedded generation on the distribution system......Page 37
1.8 Impact of embedded generation on central generation......Page 38
1.9 References......Page 39
2.1 Combined Heat and Power plants......Page 40
2.2 Renewable energy generation......Page 46
2.2.1 Small-scale hydro-generation......Page 48
2.2.2 Wind power plants......Page 50
2.2.3 Offshore wind energy......Page 58
2.2.4 Solar photovoltaic generation......Page 59
2.3 Summary......Page 65
2.4 References......Page 66
3.1 Introduction......Page 68
3.2 Types of system studies......Page 69
3.3.1 Power flow in a two-bus system......Page 70
3.3.2 Relation between flows and voltages......Page 73
3.3.3 Power flow in larger systems......Page 74
3.3.4 Solving the power flow equations......Page 77
3.3.5 Application to an embedded generation scheme......Page 78
3.4 Fault studies......Page 83
3.4.1 Balanced fault calculations......Page 84
3.4.2 Concept of fault level......Page 86
3.4.3 Application to an embedded generation scheme......Page 88
3.4.4 Unbalanced faults......Page 89
3.4.5 Application to an embedded generation scheme......Page 94
3.5 Stability studies......Page 96
3.5.1 A simple dynamic model of the mechanicalsubsystem......Page 97
3.5.2 Power transfer in a two-bus system......Page 99
3.5.4 The equal area criterion......Page 102
3.5.5 Stability studies in larger systems......Page 104
3.5.6 Stability of induction generators......Page 105
3.5.7 Application to an embedded generation scheme......Page 106
3.6 Electromagnetic transient studies......Page 110
3.8 Appendix: Equal area criterion......Page 112
4 Generators......Page 116
4.1 Synchronous generators......Page 117
4.1.1 Steady-state operation......Page 119
4.1.2 Excitation systems......Page 126
4.1.3 Operation during network disturbances......Page 128
4.2 Induction generators......Page 130
4.2.1 Steady-state operation......Page 133
4.2.2 Connection of an induction generator......Page 140
4.2.3 Self-excitation......Page 141
4.2.4 Operation during network disturbances......Page 142
4.2.5 Advanced shunt compensation for induction generators......Page 145
4.3 Power electronic converters......Page 146
4.3.1 Voltage source converters......Page 148
4.4 References......Page 150
5 Power quality......Page 152
5.1 Voltage flicker......Page 158
5.2 Harmonics......Page 161
5.3 Voltage unbalance......Page 165
5.4 Summary......Page 166
5.5 References......Page 167
6.1 Introduction......Page 168
6.2.1 Single generator on an isolated network......Page 170
6.2.2 Generator operating in parallel with other generators on an isolated network......Page 173
6.2.3 Generator embedded into utility network......Page 174
6.2.4 Protection requirements......Page 175
6.3.1 Overcurrent protection of the generator intertie......Page 179
6.3.2 Example of how overcurrent protection can be applied to an LV connected generator......Page 180
6.3.3 Negative sequence overcurrent......Page 182
6.4.1 Methods of earthing the generator......Page 183
6.4.3 Earthing of transformer connected generators......Page 186
6.5.1 Operating principle......Page 188
6.5.2 High-impedance differential......Page 190
6.5.3 Low-impedance biased differential protection......Page 192
6.6 Phase and interturn faults on the stator windings......Page 193
6.8 Under/overfrequency protection......Page 194
6.9 Reverse power relay......Page 195
6.10 Loss of excitation......Page 196
6.11 Unbalanced loading......Page 197
6.12 Generator stator thermal protection......Page 198
6.13 Overexcitation......Page 199
6.14.1 Rate of change of frequency......Page 200
6.14.2 Vector shift......Page 202
6.15 Rotor protection......Page 203
6.16 References......Page 206
7.1 Introduction......Page 208
7.2 HLI – generation capacity......Page 210
7.3 HLII – composite generation and transmission systems......Page 212
7.4.1 Conceptual requirements......Page 215
7.4.2 Probabilistic criteria and indices......Page 218
7.4.3 Historical evaluation techniques......Page 219
7.4.4 Basic reliability assessments......Page 221
7.5.1 Concepts of embedded generation......Page 223
7.5.2 Types and impact of energy sources......Page 224
7.6 Historical reliability assessment approaches......Page 225
7.7.1 Basic radial systems......Page 226
7.7.2 Embedded generation vs. network expansion......Page 230
7.8.2 Concepts of modelling......Page 232
7.8.3 Energy source model......Page 233
7.8.4 Generation model......Page 235
7.8.5 Generation plant model......Page 236
7.9 Network reliability model......Page 238
7.10.1 Capacity credit......Page 240
7.10.3 Production indices......Page 241
7.11 Study cases......Page 242
7.12 Conclusions......Page 244
7.13 References......Page 245
8.1 Introduction......Page 250
8.2.2 Voltage level related connection cost......Page 251
8.2.3 Deep v. shallow connection charges......Page 254
8.3.1 Current practice......Page 256
8.3.2 Contribution of embedded generation tonetwork security......Page 257
8.4 Allocation of losses in distribution networks with EG......Page 259
8.5 An alternative framework for distribution tariff development
......Page 265
8.5.1 Stage 1: Optimal network capacity for transport......Page 267
8.5.2 Stage 2: Security driven network expenditure......Page 268
8.5.3 Stage 3: Pricing – allocation of costs......Page 270
8.6 Conclusions......Page 272
8.7 References......Page 273
9 Concluding remarks......Page 276
Index
......Page 280