David Infield (UK University Of Strathclyde), Leon Freris (Loughborough University)
Renewable Energy in Power Systems
David Infield (UK University Of Strathclyde), Leon Freris (Loughborough University)
Renewable Energy in Power Systems
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With the growth in renewable energy (RE) generation installed capacity, many countries such as the UK are relying on higher levels of RE generation to meet targets for reduced greenhouse gas emissions. In the face of this, the integration issue is now of increasing concern, in particular to system operators.
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With the growth in renewable energy (RE) generation installed capacity, many countries such as the UK are relying on higher levels of RE generation to meet targets for reduced greenhouse gas emissions. In the face of this, the integration issue is now of increasing concern, in particular to system operators.
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Hinweis: Dieser Artikel kann nur an eine deutsche Lieferadresse ausgeliefert werden.
Produktdetails
- Produktdetails
- Verlag: John Wiley & Sons Inc
- 2 ed
- Seitenzahl: 347
- Erscheinungstermin: 30. Januar 2020
- Englisch
- Abmessung: 250mm x 175mm x 23mm
- Gewicht: 736g
- ISBN-13: 9781118649930
- ISBN-10: 1118649931
- Artikelnr.: 43782484
- Verlag: John Wiley & Sons Inc
- 2 ed
- Seitenzahl: 347
- Erscheinungstermin: 30. Januar 2020
- Englisch
- Abmessung: 250mm x 175mm x 23mm
- Gewicht: 736g
- ISBN-13: 9781118649930
- ISBN-10: 1118649931
- Artikelnr.: 43782484
DAVID INFIELD, Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow, UK LEON FRERIS, Centre for Renewable Energy Systems Technology (CREST), Loughborough University, Leicestershire, UK
Foreword xv Preface to the First Edition xix Preface to the Second Edition
xxi Acknowledgements xxiii About the Companion Website xxv 1 Energy and
Electricity 1 1.1 The World Energy Scene 1 1.1.1 History 1 1.1.2 World
Energy Consumption 1 1.1.3 Finite Resources 2 1.1.4 Energy Security and
Disparity of Use 3 1.2 The Environmental Impact of Energy Use 4 1.2.1 The
Problem 4 1.2.2 The Science 5 1.2.3 The Kyoto Protocol 7 1.2.4 Economics of
Mitigation 10 1.2.5 Efficient Energy Use 11 1.2.6 The Electricity Sector 14
1.2.7 Possible Solutions and Sustainability 15 1.3 Generating Electricity
16 1.3.1 Conversion from Other Energy Forms - The Importance of Efficiency
16 1.3.2 The Nuclear Path 17 1.3.3 Carbon Capture and Storage (CCS) 17
1.3.4 Renewables 18 1.4 The Electrical Power System 20 1.4.1 Structure of
the Electrical Power System 20 1.4.2 Integrating Renewables into Power
Systems 23 1.4.3 Distributed Generation 23 1.4.4 Renewable Energy
Penetration 24 1.4.5 Network Stability 25 References 25 2 Features of
Conventional and Renewable Generation 27 2.1 Introduction 27 2.2
Conventional Sources: Coal, Gas and Nuclear 28 2.3 Hydroelectric Power 29
2.3.1 Large-Scale Hydro 30 2.3.2 Small Hydro 31 2.3.2.1 Turbine Designs 32
2.4 Wind Power 33 2.4.1 The Resource 33 2.4.2 Wind Variability 34 2.4.3
Wind Turbines 37 2.4.4 Power Variability 40 2.4.4.1 Variability from Second
to Second 40 2.4.4.2 Variability from Minute to Minute 41 2.4.4.3
Variability from Hour to Hour and from Day-to-Day 41 2.4.4.4 Seasonal
Variability 42 2.4.5 Offshore Wind 42 2.5 PV and Solar Thermal Electricity
47 2.5.1 The Resource 47 2.5.2 The Technology 49 2.5.3 Photovoltaic Systems
49 2.5.4 Solar Thermal Electric Systems 52 2.6 Tidal Power 54 2.6.1 The
Resource 54 2.6.2 Tidal Enhancement 54 2.6.2.1 Funnelling 54 2.6.2.2
Resonance 55 2.6.2.3 Coriolis Effect 55 2.6.3 Tidal Barrages 55 2.6.4
Operational Strategies 55 2.6.4.1 Power Variability 56 2.6.5 Tidal Current
Schemes 57 2.7 Wave Power 59 2.7.1 The Resource 59 2.7.2 The Technology 59
2.7.3 Variability 60 2.8 Biomass 62 2.8.1 The Resource 62 2.8.2 Resource
Sustainability 62 2.9 Summary of Power Generation Characteristics 63 2.10
Combining Sources 64 References 65 3 Power Balance/Frequency Control 67 3.1
Introduction 67 3.1.1 The Power Balance Issue 67 3.2 Electricity Demand 68
3.2.1 Demand Curves 68 3.2.2 Load Aggregation 69 3.2.3 Demand-Side
Management - Deferrable Loads 70 3.3 Power Governing 71 3.3.1 Power
Conversion Chain 71 3.3.2 Governor Steady State Characteristics 72 3.3.3
Parallel Operation of Two Generators 73 3.3.4 A Multi-Generator System 74
3.3.5 The Steady State Power-Frequency Relationship 75 3.4 Dynamic
Frequency Control of Large Systems 76 3.4.1 Demand Matching 76 3.4.2 Demand
Forecasting 77 3.4.3 Frequency Limits 79 3.4.4 Generation Scheduling and
Reserve 79 3.4.5 Frequency Control at Different Timescales 80 3.4.6 Meeting
Demand and Ensuring Reliability 82 3.4.7 Capacity Factor and Capacity
Credit 83 3.5 Impact of Renewable Generation on Frequency Control and
Reliability 84 3.5.1 Introduction 84 3.5.2 Aggregation of Sources 85
3.5.2.1 The Monthly Distribution of Power Availability 85 3.5.2.2 The Daily
Distribution of Power Availability 85 3.5.2.3 Short Term Variability 86
3.5.2.4 The Capacity Factor 86 3.5.3 Value of Energy from the Wind 88 3.5.4
Impact on Balancing 88 3.5.5 Impact on Reliability 90 3.5.6
Discarded/Curtailed Energy 91 3.5.7 Overall Penalties Due to Increasing
Penetration 92 3.5.8 Combining Different Renewable Sources 92 3.5.9
Differences Between Electricity Systems 93 3.5.10 Limits of Penetration
from Non-Dispatchable Sources 94 3.6 Frequency Response Services from
Renewables 96 3.6.1.1 Wind Power 96 3.6.1.2 Biofuels 100 3.6.1.3 Waterpower
100 3.6.1.4 Photovoltaics 100 3.7 Frequency Control Modelling 101 3.7.1
Background 101 3.7.1.1 Modelling a Generator 101 3.7.1.2 Modelling Released
Demand 102 3.7.1.3 Modelling the Grid's Inertial Energy Store 102 3.7.2 A
Modelling Example 103 3.8 Energy Storage 105 3.8.1 Introduction 105 3.8.2
Storage Devices 106 3.8.3 Dynamic Demand Control 108 References 111 Further
Reading 113 4 Electrical Power Generation and Conditioning 115 4.1 The
Conversion of Renewable Energy into Electrical Form 115 4.2 The Synchronous
Generator 116 4.2.1 Construction and Mode of Operation 116 4.2.2 The
Rotating Magnetic Field 119 4.2.3 Synchronous Generator Operation When Grid
Connected 120 4.2.4 The Synchronous Generator Equivalent Circuit 122 4.2.5
Power Transfer Equations 123 4.2.6 Three-Phase Equations 124 4.2.7
Four-Quadrant Operation 125 4.2.8 Power-Load Angle Characteristic 125 4.3
The Transformer 126 4.3.1 Transformer Basics 126 4.3.2 The Transformer
Equivalent Circuit 128 4.3.3 Further Details on Transformers 129 4.4 The
Asynchronous Generator 130 4.4.1 Construction and Properties 130 4.4.2 The
Induction Machine Equivalent Circuit 132 4.4.3 The Induction Machine
Efficiency 134 4.4.4 The Induction Machine Speed-Torque Characteristic 134
4.4.5 Induction Generator Reactive Power 137 4.4.6 Comparison Between
Synchronous and Asynchronous Generators 137 4.5 Power Electronics 139 4.5.1
Introduction 139 4.5.2 Power-Semiconductor Devices 139 4.5.2.1 Diodes 139
4.5.2.2 Thyristors 139 4.5.2.3 Transistors 140 4.5.3 Diode Bridge Rectifier
141 4.5.4 Harmonics 142 4.5.5 The Thyristor Bridge Converter 143 4.5.6 The
Transistor Bridge 145 4.5.6.1 Basic Square Wave 146 4.5.6.2 Quasi-Sine Wave
(Modified Square Wave) 146 4.5.6.3 Pulse-Width Modulation 146 4.5.6.4
Comparison of Switching Methods 148 4.5.6.5 Output Control in a
Grid-Connected Inverter 148 4.5.6.6 The Three-Phase Bridge 149 4.5.7
Converter Internal Control Systems 149 4.5.8 DC-DC Converters 150 4.5.8.1
Step-Down DC-DC Converter 150 4.5.8.2 Step-Up DC-DC Converter 150 4.5.9
Multi-Level Converters 151 4.5.10 Matrix Converters 151 4.5.11 Z-Source
Converters 151 4.6 Applications to Renewable Energy Generators 152 4.6.1
Applications to PV Systems 152 4.6.1.1 PV System Characteristics 152
4.6.1.2 Basic Grid-Connected PV Inverter 153 4.6.1.3 Transformerless
Grid-Connected PV Inverter 153 4.6.1.4 PV Inverter Using a High-Frequency
Transformer 154 4.6.1.5 PV Inverter Using a Steering Bridge 154 4.6.1.6 PV
Inverters for Stand-Alone Operation 155 4.6.2 Applications to Wind Power
155 4.6.2.1 Fixed Versus Variable Speed - Energy Capture [4] 155 4.6.2.2
Fixed Versus Variable Speed - Dynamics 156 4.6.3 Synchronous Generator
Supplying an Autonomous Network 157 4.6.3.1 Fixed-Speed Wind Turbines 157
4.6.3.2 Variable Slip Wind Turbines 158 4.6.4 The Principle of Slip Energy
Recovery 159 4.6.4.1 DFIG Wind Turbines 160 4.6.4.2 Wind Turbines with Full
Converters 162 4.6.5 Synchronous Generators in Wind Turbines 162 4.6.6
Gearless Wind Turbines 163 4.6.7 Hybrid Drive Train Designs 164 4.6.8 DC
Transmission for Wind 165 4.7 Applications to Small Scale Hydro 166 4.8
Applications to Tidal Stream Turbines 167 References 168 5 Power-System
Analysis 171 5.1 Introduction 171 5.2 The Transmission System 171 5.2.1
Single-Phase Representation 173 5.2.2 Transmission and Distribution Systems
173 5.2.3 Example Networks 174 5.3 Voltage Control 176 5.4 Power Flow in an
Individual Section of Line 178 5.4.1 Electrical Characteristics of Lines
and Cables 178 5.4.2 Single-Phase Equivalent Circuit 178 5.4.3 Voltage Drop
Calculation 179 5.4.4 Simplifications and Conclusions 180 5.5 Reactive
Power Management 181 5.5.1 Reactive Power Compensation Equipment 182
5.5.1.1 Tap Changers and Voltage Regulators 182 5.5.1.2 AVRs 183 5.5.1.3
Static Compensators 184 5.5.1.4 FACTS 184 5.5.1.5 RE Generator Interfaces
184 5.6 Load-Flow and Power-System Simulation 184 5.6.1 Uses of Load Flow
184 5.6.2 A Particular Case 185 5.6.3 Network Data 186 5.6.4
Load/Generation Data 186 5.6.4.1 Time Dependence 186 5.6.4.2 Types of Nodes
(Buses) 187 5.6.5 The Load-Flow Calculations 188 5.6.6 Results 189 5.6.7
Unbalanced Load-Flow 189 5.7 Faults and Protection 190 5.7.1 Short-Circuit
Fault Currents 191 5.7.2 Symmetrical Three-Phase Fault Current 191 5.7.3
Fault Currents in General 191 5.7.4 Fault Level (Short-Circuit Level) -Weak
Grids 192 5.7.5 Thévenin Equivalent Circuit 193 5.8 Time Varying and
Dynamic Simulations 193 5.9 Power-System Stability 194 5.9.1 Equal Area
Stability Criterion 195 5.9.2 Power-System Stabilisers 196 5.10 Dynamic
Line Rating 196 5.11 Reliability Analysis 197 References 197 6 Renewable
Energy Generation in Power Systems 199 6.1 Distributed Generation 199 6.1.1
Introduction 199 6.1.2 Point of Common Coupling (PCC) 200 6.1.3 Connection
Voltage 200 6.2 Voltage Effects 201 6.2.1 Steady State Voltage Rise 201
6.2.2 Automatic Voltage Control - Tap Changers 202 6.2.3 Active and
Reactive Power from Renewable Energy Generators 203 6.2.4 Example Load Flow
204 6.3 Thermal Limits 207 6.3.1 Overhead Lines and Cables 207 6.3.2
Transformers 208 6.4 Other Embedded Generation Issues 208 6.4.1 Flicker,
Voltage Steps and Dips 208 6.4.1.1 Flicker 208 6.4.1.2 Steps and Dips 209
6.4.2 Harmonics/Distortion 209 6.4.3 Phase Voltage Imbalance 210 6.4.4
Network Reinforcement 211 6.4.5 Network Losses 211 6.4.6 Fault Level
Increase 211 6.5 Islanding 212 6.5.1 Introduction 212 6.5.2 Loss-of-Mains
Protection for Rotating Machines 213 6.5.3 Loss-of-Mains Protection for
Inverters 213 6.6 Fault Ride-Through 214 6.7 Generator and Converter
Characteristics 215 References 216 7 Power System Economics and the
Electricity Market 219 7.1 Introduction 219 7.2 The Costs of Electricity
Generation 219 7.2.1 Capital and Running Costs of Renewable and
Conventional Generation Plant 219 7.2.2 Total Generation Costs 221 7.3
Economic Optimisation in Power Systems 221 7.3.1 Diversity of Generator
Characteristics in a Power System 221 7.3.2 Optimum Economic Dispatch 221
7.3.3 Equal Incremental Cost Dispatch 224 7.3.4 OED with Several Units and
Generation Limits 225 7.3.5 Costs on a Level Playing Field 228 7.4 External
Costs 229 7.4.1 Introduction 229 7.4.2 Types of External Cost 230 7.4.3 The
Kyoto Protocol and Subsequent Agreements 231 7.4.4 Costing Pollution 233
7.5 Effects of Embedded Generation 234 7.5.1 Value of Energy At Various
Points of the Network 234 7.5.2 An Example Cash-Flow Analysis 235 7.5.3
Value of Embedded Generation - Regional and Local Issues 237 7.5.4 Capacity
Credit 238 7.5.5 Summary 241 7.6 Support Mechanisms for Renewable Energy
241 7.6.1 Introduction 241 7.6.2 Feed-in Law 242 7.6.3 Quota System 242
7.6.3.1 Renewables Obligation (RO) 242 7.6.3.2 Contract for Difference
(CFD) 243 7.6.4 Carbon Tax 243 7.6.4.1 Climate Change Levy 243 7.6.4.2
Eco-Tax Reform 243 7.6.4.3 Tax Relief 244 7.7 Electricity Markets 244 7.7.1
Introduction 244 7.7.2 The UK Electricity Supply Industry 244 7.7.2.1 The
State-Owned Central Electricity-Generating Board 244 7.7.2.2 The
Electricity Pool 244 7.7.2.3 The Operation of the Pool and Pool Rules 245
7.7.2.4 Hedging 246 7.7.2.5 Electricity Market Reform (EMR) 247 7.7.2.6
Ancillary Services 247 7.7.2.7 Marketing Green Electricity 248 References
248 8 The Future - Towards a Sustainable Electricity Supply System 249 8.1
Introduction 249 8.2 The Future of Wind Power 251 8.2.1 Large Wind Turbines
251 8.2.2 Offshore Wind Farm Development 254 8.2.2.1 Electrical Integration
256 8.2.2.2 DC Transmission for Wind 257 8.2.2.3 Innovative Collector
Systems 257 8.2.2.4 A Proposed European DC Supergrid 257 8.2.2.5 Smarter
Wind Farms 260 8.2.3 Building Integrated Wind Turbines 262 8.3 The Future
of Solar Power 264 8.3.1 PV Technology Development 264 8.3.1.1 Different
Deployment Options 265 8.3.2 Solar Thermal Electric Systems 267 8.4 The
Future of Biofuels 268 8.5 Geothermal Power 271 8.6 The Future of Hydro and
Marine Power 271 8.7 The Shape of Future Networks 272 8.7.1 Transmission
System Evolution 273 8.7.2 Low Inertia Power Systems 275 8.7.3 Distribution
Network Evolution 276 8.7.3.1 Active Networks 277 8.7.4 Problems Associated
with Distributed Generation 278 8.7.4.1 Fault Levels 278 8.7.4.2 Voltage
Levels 278 8.7.4.3 Network Security 279 8.7.4.4 Network Stability 279 8.7.5
Options to Ameliorate the Technical Difficulties 279 8.7.5.1 Planning
Standards 279 8.7.5.2 Using Power Electronics Technology 279 8.7.5.3
Islanding 280 8.7.5.4 Dynamic Loads 280 8.7.5.5 Demand-Side Management of
Loads 281 8.7.5.6 Storage 282 8.7.5.7 Microgrids 282 8.7.5.8 Virtual Power
Stations 283 8.8 Conclusions 283 References 285 Appendix A Basic Electric
Power Engineering Concepts 289 A.1 Introduction 289 A.2 Generators and
Consumers of Energy 289 A.3 Why AC? 291 A.4 AC Waveforms 291 A.5 Response
of Circuit Components to AC 292 A.5.1 Resistance 292 A.5.2 Inductance 293
A.5.3 Capacitance 295 A.6 Phasors 296 A.7 Phasor Addition 297 A.8
Rectangular Notation 298 A.9 Reactance and Impedance 300 A.9.1 Resistance
300 A.9.2 Inductance 301 A.9.3 Capacitance 301 A.9.4 Impedance 301 A.10
Power in AC Circuits 302 A.11 Reactive Power 304 A.12 Complex Power 305
A.13 Conservation of Active and Reactive Power 306 A.14 Effects of Reactive
Power Flow - Power Factor Correction 307 A.15 Three-Phase AC 308 A.16 The
Thévenin Equivalent Circuit 310 Reference 311 Index 313
xxi Acknowledgements xxiii About the Companion Website xxv 1 Energy and
Electricity 1 1.1 The World Energy Scene 1 1.1.1 History 1 1.1.2 World
Energy Consumption 1 1.1.3 Finite Resources 2 1.1.4 Energy Security and
Disparity of Use 3 1.2 The Environmental Impact of Energy Use 4 1.2.1 The
Problem 4 1.2.2 The Science 5 1.2.3 The Kyoto Protocol 7 1.2.4 Economics of
Mitigation 10 1.2.5 Efficient Energy Use 11 1.2.6 The Electricity Sector 14
1.2.7 Possible Solutions and Sustainability 15 1.3 Generating Electricity
16 1.3.1 Conversion from Other Energy Forms - The Importance of Efficiency
16 1.3.2 The Nuclear Path 17 1.3.3 Carbon Capture and Storage (CCS) 17
1.3.4 Renewables 18 1.4 The Electrical Power System 20 1.4.1 Structure of
the Electrical Power System 20 1.4.2 Integrating Renewables into Power
Systems 23 1.4.3 Distributed Generation 23 1.4.4 Renewable Energy
Penetration 24 1.4.5 Network Stability 25 References 25 2 Features of
Conventional and Renewable Generation 27 2.1 Introduction 27 2.2
Conventional Sources: Coal, Gas and Nuclear 28 2.3 Hydroelectric Power 29
2.3.1 Large-Scale Hydro 30 2.3.2 Small Hydro 31 2.3.2.1 Turbine Designs 32
2.4 Wind Power 33 2.4.1 The Resource 33 2.4.2 Wind Variability 34 2.4.3
Wind Turbines 37 2.4.4 Power Variability 40 2.4.4.1 Variability from Second
to Second 40 2.4.4.2 Variability from Minute to Minute 41 2.4.4.3
Variability from Hour to Hour and from Day-to-Day 41 2.4.4.4 Seasonal
Variability 42 2.4.5 Offshore Wind 42 2.5 PV and Solar Thermal Electricity
47 2.5.1 The Resource 47 2.5.2 The Technology 49 2.5.3 Photovoltaic Systems
49 2.5.4 Solar Thermal Electric Systems 52 2.6 Tidal Power 54 2.6.1 The
Resource 54 2.6.2 Tidal Enhancement 54 2.6.2.1 Funnelling 54 2.6.2.2
Resonance 55 2.6.2.3 Coriolis Effect 55 2.6.3 Tidal Barrages 55 2.6.4
Operational Strategies 55 2.6.4.1 Power Variability 56 2.6.5 Tidal Current
Schemes 57 2.7 Wave Power 59 2.7.1 The Resource 59 2.7.2 The Technology 59
2.7.3 Variability 60 2.8 Biomass 62 2.8.1 The Resource 62 2.8.2 Resource
Sustainability 62 2.9 Summary of Power Generation Characteristics 63 2.10
Combining Sources 64 References 65 3 Power Balance/Frequency Control 67 3.1
Introduction 67 3.1.1 The Power Balance Issue 67 3.2 Electricity Demand 68
3.2.1 Demand Curves 68 3.2.2 Load Aggregation 69 3.2.3 Demand-Side
Management - Deferrable Loads 70 3.3 Power Governing 71 3.3.1 Power
Conversion Chain 71 3.3.2 Governor Steady State Characteristics 72 3.3.3
Parallel Operation of Two Generators 73 3.3.4 A Multi-Generator System 74
3.3.5 The Steady State Power-Frequency Relationship 75 3.4 Dynamic
Frequency Control of Large Systems 76 3.4.1 Demand Matching 76 3.4.2 Demand
Forecasting 77 3.4.3 Frequency Limits 79 3.4.4 Generation Scheduling and
Reserve 79 3.4.5 Frequency Control at Different Timescales 80 3.4.6 Meeting
Demand and Ensuring Reliability 82 3.4.7 Capacity Factor and Capacity
Credit 83 3.5 Impact of Renewable Generation on Frequency Control and
Reliability 84 3.5.1 Introduction 84 3.5.2 Aggregation of Sources 85
3.5.2.1 The Monthly Distribution of Power Availability 85 3.5.2.2 The Daily
Distribution of Power Availability 85 3.5.2.3 Short Term Variability 86
3.5.2.4 The Capacity Factor 86 3.5.3 Value of Energy from the Wind 88 3.5.4
Impact on Balancing 88 3.5.5 Impact on Reliability 90 3.5.6
Discarded/Curtailed Energy 91 3.5.7 Overall Penalties Due to Increasing
Penetration 92 3.5.8 Combining Different Renewable Sources 92 3.5.9
Differences Between Electricity Systems 93 3.5.10 Limits of Penetration
from Non-Dispatchable Sources 94 3.6 Frequency Response Services from
Renewables 96 3.6.1.1 Wind Power 96 3.6.1.2 Biofuels 100 3.6.1.3 Waterpower
100 3.6.1.4 Photovoltaics 100 3.7 Frequency Control Modelling 101 3.7.1
Background 101 3.7.1.1 Modelling a Generator 101 3.7.1.2 Modelling Released
Demand 102 3.7.1.3 Modelling the Grid's Inertial Energy Store 102 3.7.2 A
Modelling Example 103 3.8 Energy Storage 105 3.8.1 Introduction 105 3.8.2
Storage Devices 106 3.8.3 Dynamic Demand Control 108 References 111 Further
Reading 113 4 Electrical Power Generation and Conditioning 115 4.1 The
Conversion of Renewable Energy into Electrical Form 115 4.2 The Synchronous
Generator 116 4.2.1 Construction and Mode of Operation 116 4.2.2 The
Rotating Magnetic Field 119 4.2.3 Synchronous Generator Operation When Grid
Connected 120 4.2.4 The Synchronous Generator Equivalent Circuit 122 4.2.5
Power Transfer Equations 123 4.2.6 Three-Phase Equations 124 4.2.7
Four-Quadrant Operation 125 4.2.8 Power-Load Angle Characteristic 125 4.3
The Transformer 126 4.3.1 Transformer Basics 126 4.3.2 The Transformer
Equivalent Circuit 128 4.3.3 Further Details on Transformers 129 4.4 The
Asynchronous Generator 130 4.4.1 Construction and Properties 130 4.4.2 The
Induction Machine Equivalent Circuit 132 4.4.3 The Induction Machine
Efficiency 134 4.4.4 The Induction Machine Speed-Torque Characteristic 134
4.4.5 Induction Generator Reactive Power 137 4.4.6 Comparison Between
Synchronous and Asynchronous Generators 137 4.5 Power Electronics 139 4.5.1
Introduction 139 4.5.2 Power-Semiconductor Devices 139 4.5.2.1 Diodes 139
4.5.2.2 Thyristors 139 4.5.2.3 Transistors 140 4.5.3 Diode Bridge Rectifier
141 4.5.4 Harmonics 142 4.5.5 The Thyristor Bridge Converter 143 4.5.6 The
Transistor Bridge 145 4.5.6.1 Basic Square Wave 146 4.5.6.2 Quasi-Sine Wave
(Modified Square Wave) 146 4.5.6.3 Pulse-Width Modulation 146 4.5.6.4
Comparison of Switching Methods 148 4.5.6.5 Output Control in a
Grid-Connected Inverter 148 4.5.6.6 The Three-Phase Bridge 149 4.5.7
Converter Internal Control Systems 149 4.5.8 DC-DC Converters 150 4.5.8.1
Step-Down DC-DC Converter 150 4.5.8.2 Step-Up DC-DC Converter 150 4.5.9
Multi-Level Converters 151 4.5.10 Matrix Converters 151 4.5.11 Z-Source
Converters 151 4.6 Applications to Renewable Energy Generators 152 4.6.1
Applications to PV Systems 152 4.6.1.1 PV System Characteristics 152
4.6.1.2 Basic Grid-Connected PV Inverter 153 4.6.1.3 Transformerless
Grid-Connected PV Inverter 153 4.6.1.4 PV Inverter Using a High-Frequency
Transformer 154 4.6.1.5 PV Inverter Using a Steering Bridge 154 4.6.1.6 PV
Inverters for Stand-Alone Operation 155 4.6.2 Applications to Wind Power
155 4.6.2.1 Fixed Versus Variable Speed - Energy Capture [4] 155 4.6.2.2
Fixed Versus Variable Speed - Dynamics 156 4.6.3 Synchronous Generator
Supplying an Autonomous Network 157 4.6.3.1 Fixed-Speed Wind Turbines 157
4.6.3.2 Variable Slip Wind Turbines 158 4.6.4 The Principle of Slip Energy
Recovery 159 4.6.4.1 DFIG Wind Turbines 160 4.6.4.2 Wind Turbines with Full
Converters 162 4.6.5 Synchronous Generators in Wind Turbines 162 4.6.6
Gearless Wind Turbines 163 4.6.7 Hybrid Drive Train Designs 164 4.6.8 DC
Transmission for Wind 165 4.7 Applications to Small Scale Hydro 166 4.8
Applications to Tidal Stream Turbines 167 References 168 5 Power-System
Analysis 171 5.1 Introduction 171 5.2 The Transmission System 171 5.2.1
Single-Phase Representation 173 5.2.2 Transmission and Distribution Systems
173 5.2.3 Example Networks 174 5.3 Voltage Control 176 5.4 Power Flow in an
Individual Section of Line 178 5.4.1 Electrical Characteristics of Lines
and Cables 178 5.4.2 Single-Phase Equivalent Circuit 178 5.4.3 Voltage Drop
Calculation 179 5.4.4 Simplifications and Conclusions 180 5.5 Reactive
Power Management 181 5.5.1 Reactive Power Compensation Equipment 182
5.5.1.1 Tap Changers and Voltage Regulators 182 5.5.1.2 AVRs 183 5.5.1.3
Static Compensators 184 5.5.1.4 FACTS 184 5.5.1.5 RE Generator Interfaces
184 5.6 Load-Flow and Power-System Simulation 184 5.6.1 Uses of Load Flow
184 5.6.2 A Particular Case 185 5.6.3 Network Data 186 5.6.4
Load/Generation Data 186 5.6.4.1 Time Dependence 186 5.6.4.2 Types of Nodes
(Buses) 187 5.6.5 The Load-Flow Calculations 188 5.6.6 Results 189 5.6.7
Unbalanced Load-Flow 189 5.7 Faults and Protection 190 5.7.1 Short-Circuit
Fault Currents 191 5.7.2 Symmetrical Three-Phase Fault Current 191 5.7.3
Fault Currents in General 191 5.7.4 Fault Level (Short-Circuit Level) -Weak
Grids 192 5.7.5 Thévenin Equivalent Circuit 193 5.8 Time Varying and
Dynamic Simulations 193 5.9 Power-System Stability 194 5.9.1 Equal Area
Stability Criterion 195 5.9.2 Power-System Stabilisers 196 5.10 Dynamic
Line Rating 196 5.11 Reliability Analysis 197 References 197 6 Renewable
Energy Generation in Power Systems 199 6.1 Distributed Generation 199 6.1.1
Introduction 199 6.1.2 Point of Common Coupling (PCC) 200 6.1.3 Connection
Voltage 200 6.2 Voltage Effects 201 6.2.1 Steady State Voltage Rise 201
6.2.2 Automatic Voltage Control - Tap Changers 202 6.2.3 Active and
Reactive Power from Renewable Energy Generators 203 6.2.4 Example Load Flow
204 6.3 Thermal Limits 207 6.3.1 Overhead Lines and Cables 207 6.3.2
Transformers 208 6.4 Other Embedded Generation Issues 208 6.4.1 Flicker,
Voltage Steps and Dips 208 6.4.1.1 Flicker 208 6.4.1.2 Steps and Dips 209
6.4.2 Harmonics/Distortion 209 6.4.3 Phase Voltage Imbalance 210 6.4.4
Network Reinforcement 211 6.4.5 Network Losses 211 6.4.6 Fault Level
Increase 211 6.5 Islanding 212 6.5.1 Introduction 212 6.5.2 Loss-of-Mains
Protection for Rotating Machines 213 6.5.3 Loss-of-Mains Protection for
Inverters 213 6.6 Fault Ride-Through 214 6.7 Generator and Converter
Characteristics 215 References 216 7 Power System Economics and the
Electricity Market 219 7.1 Introduction 219 7.2 The Costs of Electricity
Generation 219 7.2.1 Capital and Running Costs of Renewable and
Conventional Generation Plant 219 7.2.2 Total Generation Costs 221 7.3
Economic Optimisation in Power Systems 221 7.3.1 Diversity of Generator
Characteristics in a Power System 221 7.3.2 Optimum Economic Dispatch 221
7.3.3 Equal Incremental Cost Dispatch 224 7.3.4 OED with Several Units and
Generation Limits 225 7.3.5 Costs on a Level Playing Field 228 7.4 External
Costs 229 7.4.1 Introduction 229 7.4.2 Types of External Cost 230 7.4.3 The
Kyoto Protocol and Subsequent Agreements 231 7.4.4 Costing Pollution 233
7.5 Effects of Embedded Generation 234 7.5.1 Value of Energy At Various
Points of the Network 234 7.5.2 An Example Cash-Flow Analysis 235 7.5.3
Value of Embedded Generation - Regional and Local Issues 237 7.5.4 Capacity
Credit 238 7.5.5 Summary 241 7.6 Support Mechanisms for Renewable Energy
241 7.6.1 Introduction 241 7.6.2 Feed-in Law 242 7.6.3 Quota System 242
7.6.3.1 Renewables Obligation (RO) 242 7.6.3.2 Contract for Difference
(CFD) 243 7.6.4 Carbon Tax 243 7.6.4.1 Climate Change Levy 243 7.6.4.2
Eco-Tax Reform 243 7.6.4.3 Tax Relief 244 7.7 Electricity Markets 244 7.7.1
Introduction 244 7.7.2 The UK Electricity Supply Industry 244 7.7.2.1 The
State-Owned Central Electricity-Generating Board 244 7.7.2.2 The
Electricity Pool 244 7.7.2.3 The Operation of the Pool and Pool Rules 245
7.7.2.4 Hedging 246 7.7.2.5 Electricity Market Reform (EMR) 247 7.7.2.6
Ancillary Services 247 7.7.2.7 Marketing Green Electricity 248 References
248 8 The Future - Towards a Sustainable Electricity Supply System 249 8.1
Introduction 249 8.2 The Future of Wind Power 251 8.2.1 Large Wind Turbines
251 8.2.2 Offshore Wind Farm Development 254 8.2.2.1 Electrical Integration
256 8.2.2.2 DC Transmission for Wind 257 8.2.2.3 Innovative Collector
Systems 257 8.2.2.4 A Proposed European DC Supergrid 257 8.2.2.5 Smarter
Wind Farms 260 8.2.3 Building Integrated Wind Turbines 262 8.3 The Future
of Solar Power 264 8.3.1 PV Technology Development 264 8.3.1.1 Different
Deployment Options 265 8.3.2 Solar Thermal Electric Systems 267 8.4 The
Future of Biofuels 268 8.5 Geothermal Power 271 8.6 The Future of Hydro and
Marine Power 271 8.7 The Shape of Future Networks 272 8.7.1 Transmission
System Evolution 273 8.7.2 Low Inertia Power Systems 275 8.7.3 Distribution
Network Evolution 276 8.7.3.1 Active Networks 277 8.7.4 Problems Associated
with Distributed Generation 278 8.7.4.1 Fault Levels 278 8.7.4.2 Voltage
Levels 278 8.7.4.3 Network Security 279 8.7.4.4 Network Stability 279 8.7.5
Options to Ameliorate the Technical Difficulties 279 8.7.5.1 Planning
Standards 279 8.7.5.2 Using Power Electronics Technology 279 8.7.5.3
Islanding 280 8.7.5.4 Dynamic Loads 280 8.7.5.5 Demand-Side Management of
Loads 281 8.7.5.6 Storage 282 8.7.5.7 Microgrids 282 8.7.5.8 Virtual Power
Stations 283 8.8 Conclusions 283 References 285 Appendix A Basic Electric
Power Engineering Concepts 289 A.1 Introduction 289 A.2 Generators and
Consumers of Energy 289 A.3 Why AC? 291 A.4 AC Waveforms 291 A.5 Response
of Circuit Components to AC 292 A.5.1 Resistance 292 A.5.2 Inductance 293
A.5.3 Capacitance 295 A.6 Phasors 296 A.7 Phasor Addition 297 A.8
Rectangular Notation 298 A.9 Reactance and Impedance 300 A.9.1 Resistance
300 A.9.2 Inductance 301 A.9.3 Capacitance 301 A.9.4 Impedance 301 A.10
Power in AC Circuits 302 A.11 Reactive Power 304 A.12 Complex Power 305
A.13 Conservation of Active and Reactive Power 306 A.14 Effects of Reactive
Power Flow - Power Factor Correction 307 A.15 Three-Phase AC 308 A.16 The
Thévenin Equivalent Circuit 310 Reference 311 Index 313
Foreword xv Preface to the First Edition xix Preface to the Second Edition
xxi Acknowledgements xxiii About the Companion Website xxv 1 Energy and
Electricity 1 1.1 The World Energy Scene 1 1.1.1 History 1 1.1.2 World
Energy Consumption 1 1.1.3 Finite Resources 2 1.1.4 Energy Security and
Disparity of Use 3 1.2 The Environmental Impact of Energy Use 4 1.2.1 The
Problem 4 1.2.2 The Science 5 1.2.3 The Kyoto Protocol 7 1.2.4 Economics of
Mitigation 10 1.2.5 Efficient Energy Use 11 1.2.6 The Electricity Sector 14
1.2.7 Possible Solutions and Sustainability 15 1.3 Generating Electricity
16 1.3.1 Conversion from Other Energy Forms - The Importance of Efficiency
16 1.3.2 The Nuclear Path 17 1.3.3 Carbon Capture and Storage (CCS) 17
1.3.4 Renewables 18 1.4 The Electrical Power System 20 1.4.1 Structure of
the Electrical Power System 20 1.4.2 Integrating Renewables into Power
Systems 23 1.4.3 Distributed Generation 23 1.4.4 Renewable Energy
Penetration 24 1.4.5 Network Stability 25 References 25 2 Features of
Conventional and Renewable Generation 27 2.1 Introduction 27 2.2
Conventional Sources: Coal, Gas and Nuclear 28 2.3 Hydroelectric Power 29
2.3.1 Large-Scale Hydro 30 2.3.2 Small Hydro 31 2.3.2.1 Turbine Designs 32
2.4 Wind Power 33 2.4.1 The Resource 33 2.4.2 Wind Variability 34 2.4.3
Wind Turbines 37 2.4.4 Power Variability 40 2.4.4.1 Variability from Second
to Second 40 2.4.4.2 Variability from Minute to Minute 41 2.4.4.3
Variability from Hour to Hour and from Day-to-Day 41 2.4.4.4 Seasonal
Variability 42 2.4.5 Offshore Wind 42 2.5 PV and Solar Thermal Electricity
47 2.5.1 The Resource 47 2.5.2 The Technology 49 2.5.3 Photovoltaic Systems
49 2.5.4 Solar Thermal Electric Systems 52 2.6 Tidal Power 54 2.6.1 The
Resource 54 2.6.2 Tidal Enhancement 54 2.6.2.1 Funnelling 54 2.6.2.2
Resonance 55 2.6.2.3 Coriolis Effect 55 2.6.3 Tidal Barrages 55 2.6.4
Operational Strategies 55 2.6.4.1 Power Variability 56 2.6.5 Tidal Current
Schemes 57 2.7 Wave Power 59 2.7.1 The Resource 59 2.7.2 The Technology 59
2.7.3 Variability 60 2.8 Biomass 62 2.8.1 The Resource 62 2.8.2 Resource
Sustainability 62 2.9 Summary of Power Generation Characteristics 63 2.10
Combining Sources 64 References 65 3 Power Balance/Frequency Control 67 3.1
Introduction 67 3.1.1 The Power Balance Issue 67 3.2 Electricity Demand 68
3.2.1 Demand Curves 68 3.2.2 Load Aggregation 69 3.2.3 Demand-Side
Management - Deferrable Loads 70 3.3 Power Governing 71 3.3.1 Power
Conversion Chain 71 3.3.2 Governor Steady State Characteristics 72 3.3.3
Parallel Operation of Two Generators 73 3.3.4 A Multi-Generator System 74
3.3.5 The Steady State Power-Frequency Relationship 75 3.4 Dynamic
Frequency Control of Large Systems 76 3.4.1 Demand Matching 76 3.4.2 Demand
Forecasting 77 3.4.3 Frequency Limits 79 3.4.4 Generation Scheduling and
Reserve 79 3.4.5 Frequency Control at Different Timescales 80 3.4.6 Meeting
Demand and Ensuring Reliability 82 3.4.7 Capacity Factor and Capacity
Credit 83 3.5 Impact of Renewable Generation on Frequency Control and
Reliability 84 3.5.1 Introduction 84 3.5.2 Aggregation of Sources 85
3.5.2.1 The Monthly Distribution of Power Availability 85 3.5.2.2 The Daily
Distribution of Power Availability 85 3.5.2.3 Short Term Variability 86
3.5.2.4 The Capacity Factor 86 3.5.3 Value of Energy from the Wind 88 3.5.4
Impact on Balancing 88 3.5.5 Impact on Reliability 90 3.5.6
Discarded/Curtailed Energy 91 3.5.7 Overall Penalties Due to Increasing
Penetration 92 3.5.8 Combining Different Renewable Sources 92 3.5.9
Differences Between Electricity Systems 93 3.5.10 Limits of Penetration
from Non-Dispatchable Sources 94 3.6 Frequency Response Services from
Renewables 96 3.6.1.1 Wind Power 96 3.6.1.2 Biofuels 100 3.6.1.3 Waterpower
100 3.6.1.4 Photovoltaics 100 3.7 Frequency Control Modelling 101 3.7.1
Background 101 3.7.1.1 Modelling a Generator 101 3.7.1.2 Modelling Released
Demand 102 3.7.1.3 Modelling the Grid's Inertial Energy Store 102 3.7.2 A
Modelling Example 103 3.8 Energy Storage 105 3.8.1 Introduction 105 3.8.2
Storage Devices 106 3.8.3 Dynamic Demand Control 108 References 111 Further
Reading 113 4 Electrical Power Generation and Conditioning 115 4.1 The
Conversion of Renewable Energy into Electrical Form 115 4.2 The Synchronous
Generator 116 4.2.1 Construction and Mode of Operation 116 4.2.2 The
Rotating Magnetic Field 119 4.2.3 Synchronous Generator Operation When Grid
Connected 120 4.2.4 The Synchronous Generator Equivalent Circuit 122 4.2.5
Power Transfer Equations 123 4.2.6 Three-Phase Equations 124 4.2.7
Four-Quadrant Operation 125 4.2.8 Power-Load Angle Characteristic 125 4.3
The Transformer 126 4.3.1 Transformer Basics 126 4.3.2 The Transformer
Equivalent Circuit 128 4.3.3 Further Details on Transformers 129 4.4 The
Asynchronous Generator 130 4.4.1 Construction and Properties 130 4.4.2 The
Induction Machine Equivalent Circuit 132 4.4.3 The Induction Machine
Efficiency 134 4.4.4 The Induction Machine Speed-Torque Characteristic 134
4.4.5 Induction Generator Reactive Power 137 4.4.6 Comparison Between
Synchronous and Asynchronous Generators 137 4.5 Power Electronics 139 4.5.1
Introduction 139 4.5.2 Power-Semiconductor Devices 139 4.5.2.1 Diodes 139
4.5.2.2 Thyristors 139 4.5.2.3 Transistors 140 4.5.3 Diode Bridge Rectifier
141 4.5.4 Harmonics 142 4.5.5 The Thyristor Bridge Converter 143 4.5.6 The
Transistor Bridge 145 4.5.6.1 Basic Square Wave 146 4.5.6.2 Quasi-Sine Wave
(Modified Square Wave) 146 4.5.6.3 Pulse-Width Modulation 146 4.5.6.4
Comparison of Switching Methods 148 4.5.6.5 Output Control in a
Grid-Connected Inverter 148 4.5.6.6 The Three-Phase Bridge 149 4.5.7
Converter Internal Control Systems 149 4.5.8 DC-DC Converters 150 4.5.8.1
Step-Down DC-DC Converter 150 4.5.8.2 Step-Up DC-DC Converter 150 4.5.9
Multi-Level Converters 151 4.5.10 Matrix Converters 151 4.5.11 Z-Source
Converters 151 4.6 Applications to Renewable Energy Generators 152 4.6.1
Applications to PV Systems 152 4.6.1.1 PV System Characteristics 152
4.6.1.2 Basic Grid-Connected PV Inverter 153 4.6.1.3 Transformerless
Grid-Connected PV Inverter 153 4.6.1.4 PV Inverter Using a High-Frequency
Transformer 154 4.6.1.5 PV Inverter Using a Steering Bridge 154 4.6.1.6 PV
Inverters for Stand-Alone Operation 155 4.6.2 Applications to Wind Power
155 4.6.2.1 Fixed Versus Variable Speed - Energy Capture [4] 155 4.6.2.2
Fixed Versus Variable Speed - Dynamics 156 4.6.3 Synchronous Generator
Supplying an Autonomous Network 157 4.6.3.1 Fixed-Speed Wind Turbines 157
4.6.3.2 Variable Slip Wind Turbines 158 4.6.4 The Principle of Slip Energy
Recovery 159 4.6.4.1 DFIG Wind Turbines 160 4.6.4.2 Wind Turbines with Full
Converters 162 4.6.5 Synchronous Generators in Wind Turbines 162 4.6.6
Gearless Wind Turbines 163 4.6.7 Hybrid Drive Train Designs 164 4.6.8 DC
Transmission for Wind 165 4.7 Applications to Small Scale Hydro 166 4.8
Applications to Tidal Stream Turbines 167 References 168 5 Power-System
Analysis 171 5.1 Introduction 171 5.2 The Transmission System 171 5.2.1
Single-Phase Representation 173 5.2.2 Transmission and Distribution Systems
173 5.2.3 Example Networks 174 5.3 Voltage Control 176 5.4 Power Flow in an
Individual Section of Line 178 5.4.1 Electrical Characteristics of Lines
and Cables 178 5.4.2 Single-Phase Equivalent Circuit 178 5.4.3 Voltage Drop
Calculation 179 5.4.4 Simplifications and Conclusions 180 5.5 Reactive
Power Management 181 5.5.1 Reactive Power Compensation Equipment 182
5.5.1.1 Tap Changers and Voltage Regulators 182 5.5.1.2 AVRs 183 5.5.1.3
Static Compensators 184 5.5.1.4 FACTS 184 5.5.1.5 RE Generator Interfaces
184 5.6 Load-Flow and Power-System Simulation 184 5.6.1 Uses of Load Flow
184 5.6.2 A Particular Case 185 5.6.3 Network Data 186 5.6.4
Load/Generation Data 186 5.6.4.1 Time Dependence 186 5.6.4.2 Types of Nodes
(Buses) 187 5.6.5 The Load-Flow Calculations 188 5.6.6 Results 189 5.6.7
Unbalanced Load-Flow 189 5.7 Faults and Protection 190 5.7.1 Short-Circuit
Fault Currents 191 5.7.2 Symmetrical Three-Phase Fault Current 191 5.7.3
Fault Currents in General 191 5.7.4 Fault Level (Short-Circuit Level) -Weak
Grids 192 5.7.5 Thévenin Equivalent Circuit 193 5.8 Time Varying and
Dynamic Simulations 193 5.9 Power-System Stability 194 5.9.1 Equal Area
Stability Criterion 195 5.9.2 Power-System Stabilisers 196 5.10 Dynamic
Line Rating 196 5.11 Reliability Analysis 197 References 197 6 Renewable
Energy Generation in Power Systems 199 6.1 Distributed Generation 199 6.1.1
Introduction 199 6.1.2 Point of Common Coupling (PCC) 200 6.1.3 Connection
Voltage 200 6.2 Voltage Effects 201 6.2.1 Steady State Voltage Rise 201
6.2.2 Automatic Voltage Control - Tap Changers 202 6.2.3 Active and
Reactive Power from Renewable Energy Generators 203 6.2.4 Example Load Flow
204 6.3 Thermal Limits 207 6.3.1 Overhead Lines and Cables 207 6.3.2
Transformers 208 6.4 Other Embedded Generation Issues 208 6.4.1 Flicker,
Voltage Steps and Dips 208 6.4.1.1 Flicker 208 6.4.1.2 Steps and Dips 209
6.4.2 Harmonics/Distortion 209 6.4.3 Phase Voltage Imbalance 210 6.4.4
Network Reinforcement 211 6.4.5 Network Losses 211 6.4.6 Fault Level
Increase 211 6.5 Islanding 212 6.5.1 Introduction 212 6.5.2 Loss-of-Mains
Protection for Rotating Machines 213 6.5.3 Loss-of-Mains Protection for
Inverters 213 6.6 Fault Ride-Through 214 6.7 Generator and Converter
Characteristics 215 References 216 7 Power System Economics and the
Electricity Market 219 7.1 Introduction 219 7.2 The Costs of Electricity
Generation 219 7.2.1 Capital and Running Costs of Renewable and
Conventional Generation Plant 219 7.2.2 Total Generation Costs 221 7.3
Economic Optimisation in Power Systems 221 7.3.1 Diversity of Generator
Characteristics in a Power System 221 7.3.2 Optimum Economic Dispatch 221
7.3.3 Equal Incremental Cost Dispatch 224 7.3.4 OED with Several Units and
Generation Limits 225 7.3.5 Costs on a Level Playing Field 228 7.4 External
Costs 229 7.4.1 Introduction 229 7.4.2 Types of External Cost 230 7.4.3 The
Kyoto Protocol and Subsequent Agreements 231 7.4.4 Costing Pollution 233
7.5 Effects of Embedded Generation 234 7.5.1 Value of Energy At Various
Points of the Network 234 7.5.2 An Example Cash-Flow Analysis 235 7.5.3
Value of Embedded Generation - Regional and Local Issues 237 7.5.4 Capacity
Credit 238 7.5.5 Summary 241 7.6 Support Mechanisms for Renewable Energy
241 7.6.1 Introduction 241 7.6.2 Feed-in Law 242 7.6.3 Quota System 242
7.6.3.1 Renewables Obligation (RO) 242 7.6.3.2 Contract for Difference
(CFD) 243 7.6.4 Carbon Tax 243 7.6.4.1 Climate Change Levy 243 7.6.4.2
Eco-Tax Reform 243 7.6.4.3 Tax Relief 244 7.7 Electricity Markets 244 7.7.1
Introduction 244 7.7.2 The UK Electricity Supply Industry 244 7.7.2.1 The
State-Owned Central Electricity-Generating Board 244 7.7.2.2 The
Electricity Pool 244 7.7.2.3 The Operation of the Pool and Pool Rules 245
7.7.2.4 Hedging 246 7.7.2.5 Electricity Market Reform (EMR) 247 7.7.2.6
Ancillary Services 247 7.7.2.7 Marketing Green Electricity 248 References
248 8 The Future - Towards a Sustainable Electricity Supply System 249 8.1
Introduction 249 8.2 The Future of Wind Power 251 8.2.1 Large Wind Turbines
251 8.2.2 Offshore Wind Farm Development 254 8.2.2.1 Electrical Integration
256 8.2.2.2 DC Transmission for Wind 257 8.2.2.3 Innovative Collector
Systems 257 8.2.2.4 A Proposed European DC Supergrid 257 8.2.2.5 Smarter
Wind Farms 260 8.2.3 Building Integrated Wind Turbines 262 8.3 The Future
of Solar Power 264 8.3.1 PV Technology Development 264 8.3.1.1 Different
Deployment Options 265 8.3.2 Solar Thermal Electric Systems 267 8.4 The
Future of Biofuels 268 8.5 Geothermal Power 271 8.6 The Future of Hydro and
Marine Power 271 8.7 The Shape of Future Networks 272 8.7.1 Transmission
System Evolution 273 8.7.2 Low Inertia Power Systems 275 8.7.3 Distribution
Network Evolution 276 8.7.3.1 Active Networks 277 8.7.4 Problems Associated
with Distributed Generation 278 8.7.4.1 Fault Levels 278 8.7.4.2 Voltage
Levels 278 8.7.4.3 Network Security 279 8.7.4.4 Network Stability 279 8.7.5
Options to Ameliorate the Technical Difficulties 279 8.7.5.1 Planning
Standards 279 8.7.5.2 Using Power Electronics Technology 279 8.7.5.3
Islanding 280 8.7.5.4 Dynamic Loads 280 8.7.5.5 Demand-Side Management of
Loads 281 8.7.5.6 Storage 282 8.7.5.7 Microgrids 282 8.7.5.8 Virtual Power
Stations 283 8.8 Conclusions 283 References 285 Appendix A Basic Electric
Power Engineering Concepts 289 A.1 Introduction 289 A.2 Generators and
Consumers of Energy 289 A.3 Why AC? 291 A.4 AC Waveforms 291 A.5 Response
of Circuit Components to AC 292 A.5.1 Resistance 292 A.5.2 Inductance 293
A.5.3 Capacitance 295 A.6 Phasors 296 A.7 Phasor Addition 297 A.8
Rectangular Notation 298 A.9 Reactance and Impedance 300 A.9.1 Resistance
300 A.9.2 Inductance 301 A.9.3 Capacitance 301 A.9.4 Impedance 301 A.10
Power in AC Circuits 302 A.11 Reactive Power 304 A.12 Complex Power 305
A.13 Conservation of Active and Reactive Power 306 A.14 Effects of Reactive
Power Flow - Power Factor Correction 307 A.15 Three-Phase AC 308 A.16 The
Thévenin Equivalent Circuit 310 Reference 311 Index 313
xxi Acknowledgements xxiii About the Companion Website xxv 1 Energy and
Electricity 1 1.1 The World Energy Scene 1 1.1.1 History 1 1.1.2 World
Energy Consumption 1 1.1.3 Finite Resources 2 1.1.4 Energy Security and
Disparity of Use 3 1.2 The Environmental Impact of Energy Use 4 1.2.1 The
Problem 4 1.2.2 The Science 5 1.2.3 The Kyoto Protocol 7 1.2.4 Economics of
Mitigation 10 1.2.5 Efficient Energy Use 11 1.2.6 The Electricity Sector 14
1.2.7 Possible Solutions and Sustainability 15 1.3 Generating Electricity
16 1.3.1 Conversion from Other Energy Forms - The Importance of Efficiency
16 1.3.2 The Nuclear Path 17 1.3.3 Carbon Capture and Storage (CCS) 17
1.3.4 Renewables 18 1.4 The Electrical Power System 20 1.4.1 Structure of
the Electrical Power System 20 1.4.2 Integrating Renewables into Power
Systems 23 1.4.3 Distributed Generation 23 1.4.4 Renewable Energy
Penetration 24 1.4.5 Network Stability 25 References 25 2 Features of
Conventional and Renewable Generation 27 2.1 Introduction 27 2.2
Conventional Sources: Coal, Gas and Nuclear 28 2.3 Hydroelectric Power 29
2.3.1 Large-Scale Hydro 30 2.3.2 Small Hydro 31 2.3.2.1 Turbine Designs 32
2.4 Wind Power 33 2.4.1 The Resource 33 2.4.2 Wind Variability 34 2.4.3
Wind Turbines 37 2.4.4 Power Variability 40 2.4.4.1 Variability from Second
to Second 40 2.4.4.2 Variability from Minute to Minute 41 2.4.4.3
Variability from Hour to Hour and from Day-to-Day 41 2.4.4.4 Seasonal
Variability 42 2.4.5 Offshore Wind 42 2.5 PV and Solar Thermal Electricity
47 2.5.1 The Resource 47 2.5.2 The Technology 49 2.5.3 Photovoltaic Systems
49 2.5.4 Solar Thermal Electric Systems 52 2.6 Tidal Power 54 2.6.1 The
Resource 54 2.6.2 Tidal Enhancement 54 2.6.2.1 Funnelling 54 2.6.2.2
Resonance 55 2.6.2.3 Coriolis Effect 55 2.6.3 Tidal Barrages 55 2.6.4
Operational Strategies 55 2.6.4.1 Power Variability 56 2.6.5 Tidal Current
Schemes 57 2.7 Wave Power 59 2.7.1 The Resource 59 2.7.2 The Technology 59
2.7.3 Variability 60 2.8 Biomass 62 2.8.1 The Resource 62 2.8.2 Resource
Sustainability 62 2.9 Summary of Power Generation Characteristics 63 2.10
Combining Sources 64 References 65 3 Power Balance/Frequency Control 67 3.1
Introduction 67 3.1.1 The Power Balance Issue 67 3.2 Electricity Demand 68
3.2.1 Demand Curves 68 3.2.2 Load Aggregation 69 3.2.3 Demand-Side
Management - Deferrable Loads 70 3.3 Power Governing 71 3.3.1 Power
Conversion Chain 71 3.3.2 Governor Steady State Characteristics 72 3.3.3
Parallel Operation of Two Generators 73 3.3.4 A Multi-Generator System 74
3.3.5 The Steady State Power-Frequency Relationship 75 3.4 Dynamic
Frequency Control of Large Systems 76 3.4.1 Demand Matching 76 3.4.2 Demand
Forecasting 77 3.4.3 Frequency Limits 79 3.4.4 Generation Scheduling and
Reserve 79 3.4.5 Frequency Control at Different Timescales 80 3.4.6 Meeting
Demand and Ensuring Reliability 82 3.4.7 Capacity Factor and Capacity
Credit 83 3.5 Impact of Renewable Generation on Frequency Control and
Reliability 84 3.5.1 Introduction 84 3.5.2 Aggregation of Sources 85
3.5.2.1 The Monthly Distribution of Power Availability 85 3.5.2.2 The Daily
Distribution of Power Availability 85 3.5.2.3 Short Term Variability 86
3.5.2.4 The Capacity Factor 86 3.5.3 Value of Energy from the Wind 88 3.5.4
Impact on Balancing 88 3.5.5 Impact on Reliability 90 3.5.6
Discarded/Curtailed Energy 91 3.5.7 Overall Penalties Due to Increasing
Penetration 92 3.5.8 Combining Different Renewable Sources 92 3.5.9
Differences Between Electricity Systems 93 3.5.10 Limits of Penetration
from Non-Dispatchable Sources 94 3.6 Frequency Response Services from
Renewables 96 3.6.1.1 Wind Power 96 3.6.1.2 Biofuels 100 3.6.1.3 Waterpower
100 3.6.1.4 Photovoltaics 100 3.7 Frequency Control Modelling 101 3.7.1
Background 101 3.7.1.1 Modelling a Generator 101 3.7.1.2 Modelling Released
Demand 102 3.7.1.3 Modelling the Grid's Inertial Energy Store 102 3.7.2 A
Modelling Example 103 3.8 Energy Storage 105 3.8.1 Introduction 105 3.8.2
Storage Devices 106 3.8.3 Dynamic Demand Control 108 References 111 Further
Reading 113 4 Electrical Power Generation and Conditioning 115 4.1 The
Conversion of Renewable Energy into Electrical Form 115 4.2 The Synchronous
Generator 116 4.2.1 Construction and Mode of Operation 116 4.2.2 The
Rotating Magnetic Field 119 4.2.3 Synchronous Generator Operation When Grid
Connected 120 4.2.4 The Synchronous Generator Equivalent Circuit 122 4.2.5
Power Transfer Equations 123 4.2.6 Three-Phase Equations 124 4.2.7
Four-Quadrant Operation 125 4.2.8 Power-Load Angle Characteristic 125 4.3
The Transformer 126 4.3.1 Transformer Basics 126 4.3.2 The Transformer
Equivalent Circuit 128 4.3.3 Further Details on Transformers 129 4.4 The
Asynchronous Generator 130 4.4.1 Construction and Properties 130 4.4.2 The
Induction Machine Equivalent Circuit 132 4.4.3 The Induction Machine
Efficiency 134 4.4.4 The Induction Machine Speed-Torque Characteristic 134
4.4.5 Induction Generator Reactive Power 137 4.4.6 Comparison Between
Synchronous and Asynchronous Generators 137 4.5 Power Electronics 139 4.5.1
Introduction 139 4.5.2 Power-Semiconductor Devices 139 4.5.2.1 Diodes 139
4.5.2.2 Thyristors 139 4.5.2.3 Transistors 140 4.5.3 Diode Bridge Rectifier
141 4.5.4 Harmonics 142 4.5.5 The Thyristor Bridge Converter 143 4.5.6 The
Transistor Bridge 145 4.5.6.1 Basic Square Wave 146 4.5.6.2 Quasi-Sine Wave
(Modified Square Wave) 146 4.5.6.3 Pulse-Width Modulation 146 4.5.6.4
Comparison of Switching Methods 148 4.5.6.5 Output Control in a
Grid-Connected Inverter 148 4.5.6.6 The Three-Phase Bridge 149 4.5.7
Converter Internal Control Systems 149 4.5.8 DC-DC Converters 150 4.5.8.1
Step-Down DC-DC Converter 150 4.5.8.2 Step-Up DC-DC Converter 150 4.5.9
Multi-Level Converters 151 4.5.10 Matrix Converters 151 4.5.11 Z-Source
Converters 151 4.6 Applications to Renewable Energy Generators 152 4.6.1
Applications to PV Systems 152 4.6.1.1 PV System Characteristics 152
4.6.1.2 Basic Grid-Connected PV Inverter 153 4.6.1.3 Transformerless
Grid-Connected PV Inverter 153 4.6.1.4 PV Inverter Using a High-Frequency
Transformer 154 4.6.1.5 PV Inverter Using a Steering Bridge 154 4.6.1.6 PV
Inverters for Stand-Alone Operation 155 4.6.2 Applications to Wind Power
155 4.6.2.1 Fixed Versus Variable Speed - Energy Capture [4] 155 4.6.2.2
Fixed Versus Variable Speed - Dynamics 156 4.6.3 Synchronous Generator
Supplying an Autonomous Network 157 4.6.3.1 Fixed-Speed Wind Turbines 157
4.6.3.2 Variable Slip Wind Turbines 158 4.6.4 The Principle of Slip Energy
Recovery 159 4.6.4.1 DFIG Wind Turbines 160 4.6.4.2 Wind Turbines with Full
Converters 162 4.6.5 Synchronous Generators in Wind Turbines 162 4.6.6
Gearless Wind Turbines 163 4.6.7 Hybrid Drive Train Designs 164 4.6.8 DC
Transmission for Wind 165 4.7 Applications to Small Scale Hydro 166 4.8
Applications to Tidal Stream Turbines 167 References 168 5 Power-System
Analysis 171 5.1 Introduction 171 5.2 The Transmission System 171 5.2.1
Single-Phase Representation 173 5.2.2 Transmission and Distribution Systems
173 5.2.3 Example Networks 174 5.3 Voltage Control 176 5.4 Power Flow in an
Individual Section of Line 178 5.4.1 Electrical Characteristics of Lines
and Cables 178 5.4.2 Single-Phase Equivalent Circuit 178 5.4.3 Voltage Drop
Calculation 179 5.4.4 Simplifications and Conclusions 180 5.5 Reactive
Power Management 181 5.5.1 Reactive Power Compensation Equipment 182
5.5.1.1 Tap Changers and Voltage Regulators 182 5.5.1.2 AVRs 183 5.5.1.3
Static Compensators 184 5.5.1.4 FACTS 184 5.5.1.5 RE Generator Interfaces
184 5.6 Load-Flow and Power-System Simulation 184 5.6.1 Uses of Load Flow
184 5.6.2 A Particular Case 185 5.6.3 Network Data 186 5.6.4
Load/Generation Data 186 5.6.4.1 Time Dependence 186 5.6.4.2 Types of Nodes
(Buses) 187 5.6.5 The Load-Flow Calculations 188 5.6.6 Results 189 5.6.7
Unbalanced Load-Flow 189 5.7 Faults and Protection 190 5.7.1 Short-Circuit
Fault Currents 191 5.7.2 Symmetrical Three-Phase Fault Current 191 5.7.3
Fault Currents in General 191 5.7.4 Fault Level (Short-Circuit Level) -Weak
Grids 192 5.7.5 Thévenin Equivalent Circuit 193 5.8 Time Varying and
Dynamic Simulations 193 5.9 Power-System Stability 194 5.9.1 Equal Area
Stability Criterion 195 5.9.2 Power-System Stabilisers 196 5.10 Dynamic
Line Rating 196 5.11 Reliability Analysis 197 References 197 6 Renewable
Energy Generation in Power Systems 199 6.1 Distributed Generation 199 6.1.1
Introduction 199 6.1.2 Point of Common Coupling (PCC) 200 6.1.3 Connection
Voltage 200 6.2 Voltage Effects 201 6.2.1 Steady State Voltage Rise 201
6.2.2 Automatic Voltage Control - Tap Changers 202 6.2.3 Active and
Reactive Power from Renewable Energy Generators 203 6.2.4 Example Load Flow
204 6.3 Thermal Limits 207 6.3.1 Overhead Lines and Cables 207 6.3.2
Transformers 208 6.4 Other Embedded Generation Issues 208 6.4.1 Flicker,
Voltage Steps and Dips 208 6.4.1.1 Flicker 208 6.4.1.2 Steps and Dips 209
6.4.2 Harmonics/Distortion 209 6.4.3 Phase Voltage Imbalance 210 6.4.4
Network Reinforcement 211 6.4.5 Network Losses 211 6.4.6 Fault Level
Increase 211 6.5 Islanding 212 6.5.1 Introduction 212 6.5.2 Loss-of-Mains
Protection for Rotating Machines 213 6.5.3 Loss-of-Mains Protection for
Inverters 213 6.6 Fault Ride-Through 214 6.7 Generator and Converter
Characteristics 215 References 216 7 Power System Economics and the
Electricity Market 219 7.1 Introduction 219 7.2 The Costs of Electricity
Generation 219 7.2.1 Capital and Running Costs of Renewable and
Conventional Generation Plant 219 7.2.2 Total Generation Costs 221 7.3
Economic Optimisation in Power Systems 221 7.3.1 Diversity of Generator
Characteristics in a Power System 221 7.3.2 Optimum Economic Dispatch 221
7.3.3 Equal Incremental Cost Dispatch 224 7.3.4 OED with Several Units and
Generation Limits 225 7.3.5 Costs on a Level Playing Field 228 7.4 External
Costs 229 7.4.1 Introduction 229 7.4.2 Types of External Cost 230 7.4.3 The
Kyoto Protocol and Subsequent Agreements 231 7.4.4 Costing Pollution 233
7.5 Effects of Embedded Generation 234 7.5.1 Value of Energy At Various
Points of the Network 234 7.5.2 An Example Cash-Flow Analysis 235 7.5.3
Value of Embedded Generation - Regional and Local Issues 237 7.5.4 Capacity
Credit 238 7.5.5 Summary 241 7.6 Support Mechanisms for Renewable Energy
241 7.6.1 Introduction 241 7.6.2 Feed-in Law 242 7.6.3 Quota System 242
7.6.3.1 Renewables Obligation (RO) 242 7.6.3.2 Contract for Difference
(CFD) 243 7.6.4 Carbon Tax 243 7.6.4.1 Climate Change Levy 243 7.6.4.2
Eco-Tax Reform 243 7.6.4.3 Tax Relief 244 7.7 Electricity Markets 244 7.7.1
Introduction 244 7.7.2 The UK Electricity Supply Industry 244 7.7.2.1 The
State-Owned Central Electricity-Generating Board 244 7.7.2.2 The
Electricity Pool 244 7.7.2.3 The Operation of the Pool and Pool Rules 245
7.7.2.4 Hedging 246 7.7.2.5 Electricity Market Reform (EMR) 247 7.7.2.6
Ancillary Services 247 7.7.2.7 Marketing Green Electricity 248 References
248 8 The Future - Towards a Sustainable Electricity Supply System 249 8.1
Introduction 249 8.2 The Future of Wind Power 251 8.2.1 Large Wind Turbines
251 8.2.2 Offshore Wind Farm Development 254 8.2.2.1 Electrical Integration
256 8.2.2.2 DC Transmission for Wind 257 8.2.2.3 Innovative Collector
Systems 257 8.2.2.4 A Proposed European DC Supergrid 257 8.2.2.5 Smarter
Wind Farms 260 8.2.3 Building Integrated Wind Turbines 262 8.3 The Future
of Solar Power 264 8.3.1 PV Technology Development 264 8.3.1.1 Different
Deployment Options 265 8.3.2 Solar Thermal Electric Systems 267 8.4 The
Future of Biofuels 268 8.5 Geothermal Power 271 8.6 The Future of Hydro and
Marine Power 271 8.7 The Shape of Future Networks 272 8.7.1 Transmission
System Evolution 273 8.7.2 Low Inertia Power Systems 275 8.7.3 Distribution
Network Evolution 276 8.7.3.1 Active Networks 277 8.7.4 Problems Associated
with Distributed Generation 278 8.7.4.1 Fault Levels 278 8.7.4.2 Voltage
Levels 278 8.7.4.3 Network Security 279 8.7.4.4 Network Stability 279 8.7.5
Options to Ameliorate the Technical Difficulties 279 8.7.5.1 Planning
Standards 279 8.7.5.2 Using Power Electronics Technology 279 8.7.5.3
Islanding 280 8.7.5.4 Dynamic Loads 280 8.7.5.5 Demand-Side Management of
Loads 281 8.7.5.6 Storage 282 8.7.5.7 Microgrids 282 8.7.5.8 Virtual Power
Stations 283 8.8 Conclusions 283 References 285 Appendix A Basic Electric
Power Engineering Concepts 289 A.1 Introduction 289 A.2 Generators and
Consumers of Energy 289 A.3 Why AC? 291 A.4 AC Waveforms 291 A.5 Response
of Circuit Components to AC 292 A.5.1 Resistance 292 A.5.2 Inductance 293
A.5.3 Capacitance 295 A.6 Phasors 296 A.7 Phasor Addition 297 A.8
Rectangular Notation 298 A.9 Reactance and Impedance 300 A.9.1 Resistance
300 A.9.2 Inductance 301 A.9.3 Capacitance 301 A.9.4 Impedance 301 A.10
Power in AC Circuits 302 A.11 Reactive Power 304 A.12 Complex Power 305
A.13 Conservation of Active and Reactive Power 306 A.14 Effects of Reactive
Power Flow - Power Factor Correction 307 A.15 Three-Phase AC 308 A.16 The
Thévenin Equivalent Circuit 310 Reference 311 Index 313