Wind Power in Power Systems

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Chapter 1
Introduction by Thomas Ackermann

Part A: Theoretical Background and Technical Regulations

Chapter 2
Historical Development and Current Status of Wind Power by Thomas Ackermann

2.1 Introduction

2.2 Historical Background

2.2.1 Mechanical power generation

2.2.2 Electrical power generation

2.3 Current Status of Wind Power Worldwide

2.3.1 Overview of grid-connected wind power generation

2.3.2 Europe

2.3.3 North America

2.3.4 South and Central America

2.3.5 Asia and Pacific

2.3.6 Middle East and Africa

2.3.7 Overview of stand-alone generation

2.3.8 Wind power economics

2.3.9 Environmental issues

2.4 Status of Wind Turbine Technology

2.4.1 Design approaches

2.5 Conclusions

Acknowledgements

References

Chapter 3
Wind Power in Power Systems: An Introduction

By Lennart Söder and Thomas Ackermann

3.2 Power System History

3.3 Current Status of Wind Power in Power Systems

3.4 Network Integration Issues for Wind Power

3.5 Basic Electrical Engineering

3.6 Characteristics of Wind Power Generation

3.6.1 The Wind

3.6.2 The Physics

3.6.3 Wind Power Production

3.7 Basic Integration Issues Related to Wind Power

3.7.1 Consumer requirements

3.7.2 Requirements from wind farm operators

3.7.3 The integration issues

3.8 Conclusions

Appendix: A Mechanical Equivalent to Power System Operation with Wind Power

Introduction

Active power balance

Reactive power balance

References

Chapter 4
Generators and Power Electronics for Wind Turbines

By Anca D. Hansen

4.1 Introduction

4.2 State-of-the-art Technologies

4.2.1 Overview of wind turbine topologies

4.2.2 Overview of power control concepts

4.2.3 State-of-the-art generators

4.2.4 State-of-the-art power electronics

4.2.5 State-of-the-art market penetration

4.3 Generator Concepts

4.3.1 Asynchronous (induction) generator

4.3.2 The synchronous generator

4.3.3 Other types of generators

4.4 Power Electronic Concepts

4.4.1 Soft-starter

4.4.2 Capacitor bank

4.4.3 Rectifiers and inverters

4.4.4 Frequency converters

4.5 Power Electronic Solutions in Wind Farms

4.6 Conclusions

References

Chapter 5
Power Quality Standards for Wind Turbines

By John Olav Tande

5.1 Introduction

5.2 Power Quality Characteristics of Wind Turbines

5.2.1 Rated data

5.2.2 Maximum permitted power

5.2.3 Maximum measured power

5.2.4 Reactive power

5.2.5 Flicker coefficient

5.2.6 Maximum number of wind turbine switching operations

5.2.7 Flicker step factor

5.2.8 Voltage change factor

5.2.9 Harmonic currents

5.2.10 Summary power quality characteristics for various wind turbine types

5.3 Impact on Voltage Quality

5.3.1 General

5.3.2 Case study specifications

5.3.3 Slow voltage variations

5.3.4 Flicker

5.3.5 Voltage dips

5.3.6 Harmonic voltage

5.4 Discussion 93

5.5 Conclusions 94

References 95

Chapter 6
Power Quality Measurements

By Fritz Santjer

6.1 Introduction

6.2 Requirements for Power Quality Measurements

6.2.1 Guidelines

6.2.2 Specification

6.2.3 Future aspects

6.3 Power Quality Characteristics of Wind Turbines and Wind Farms

6.3.1 Power peaks

6.3.2 Reactive power

6.3.3 Harmonics

6.3.4 Flicker

6.3.5 Switching operations

6.4 Assessment Concerning the Grid Connection

6.5 Conclusions

References

Chapter 7
Technical Regulations for the Interconnection of Wind Farms to the Power System

By Julija Matevosyan, Thomas Ackermann and Sigrid M. Bolik

7.1 Introduction

7.2 Overview of Technical Regulations

7.2.1 Regulations for networks below 110 kV

7.2.2 Regulations for networks above 110 kV

7.2.3 Combined regulations

7.3 Comparison of Technical Interconnection Regulations

7.3.1 Active power control

7.3.2 Frequency control

7.3.3 Voltage control

7.3.4 Tap changers

7.3.5 Wind farm protection

7.3.6 Modelling information and verification

7.3.7 Communication and external control

7.3.8 Discussion of interconnection regulations

7.4 Technical Solutions for New Interconnection Rules

7.4.1 Absolute power constraint

7.4.2 Balance control

7.4.3 Power rate limitation control approach

7.4.4 Delta control

7.5 Interconnection Practice

7.6 Conclusions

References

Chapter 8
Power System Requirements for Wind Power

By Hannele Holttinen and Ritva Hirvonen

8.1 Introduction

8.2 Operation of the Power System

8.2.1 System reliability

8.2.2 Frequency control

8.2.3 Voltage management

8.3 Wind Power Production and the Power System

8.3.1 Production patterns of wind power

8.3.2 Variations of production and the smoothing effect

8.3.3 Predictability of wind power production

8.4 Effects of Wind Energy on the Power System

8.4.1 Short-term effects on reserves

8.4.2 Other short-term effects

8.4.3 Long-term effects on the adequacy of power capacity

8.4.4 Wind power in future power systems

8.5 Conclusions

References

Chapter 9
The Value of Wind Power

By Lennart Söder

9.1 Introduction

9.2 The Value of a Power Plant

9.2.1 Operating cost value

9.2.2 Capacity credit

9.2.3 Control value

9.2.4 Loss reduction value

9.2.5 Grid investment value

9.3 The Value of Wind Power

9.3.1 The operating cost value of wind power

9.3.2 The capacity credit of wind power

9.3.3 The control value of wind power

9.3.4 The loss reduction value of wind power

9.3.5 The grid investment value of wind power

9.4 The Market Value of Wind Power

9.4.1 The market operation cost value of wind power

9.4.2 The market capacity credit of wind power

9.4.3 The market control value of wind power

9.4.4 The market loss reduction value of wind power

9.4.5 The market grid investment value of wind power

9.5 Conclusions

References

Part B Power System Integration Experience

Chapter 10
Wind Power in the Danish Power System

By Peter Borre Eriksen and Carl Hilger

10.1 Introduction

10.2 Operational Issues

10.2.1 The Nordic market model for electricity trading

10.2.2 Different markets

10.2.3 Interaction between technical rules and the market

10.2.4 Example of how Eltra handles the balance task

10.2.5 Balancing via Nord Pool: first step

10.2.6 The accuracy of the forecasts

10.2.7 Network controller and instantaneous reserves

10.2.8 Balancing prices in the real-time market

10.2.9 Market prices fluctuating with high wind production

10.2.10 Other operational problems

10.3 System Analysis and Modelling Issues

10.3.1 Future development of wind power

10.3.2 Wind regime

10.3.3 Wind power forecast models

10.3.4 Grid connection

10.3.5 Modelling of power systems with large-scale wind power production

10.3.6 Wind power and system analysis

10.3.7 Case study CO2 reductions according to the Kyoto Protocol

10.4 Conclusions and Lessons Learned

References 232

Chapter 11
Wind Power in the German Power System: Current Status and Future

- Challenges of Maintaining Quality of Supply

By Matthias Luther, Uwe Radtke and Wilhelm R. Winter

11.1 Introduction

11.2 Current Performance of Wind Energy in Germany

11.3 Wind Power Supply in the E.ON Netz Area

11.4 Electricity System Control Requirements

11.5 Network Planning and Connection Requirements

11.6 Wind Turbines and Dynamic Performance Requirements

11.7 Object of Investigation and Constraints

11.8 Simulation Results

11.8.1 Voltage quality

11.8.2 Frequency stability

11.9 Additional Dynamic Requirements of Wind Turbines

11.10 Conclusions

References

Chapter 12
Wind Power on Weak Grids in California and the US Midwest

By H. M. Romanowitz

12.1 Introduction

12.2 The Early Weak Grid: Background

12.2.1 Tehachapi 66 kV transmission

12.2.2 VARs

12.2.3 FACTS devices

12.2.4 Development of wind energy on the Tehachapi 66 kV grid

12.2.5 Reliable generation

12.2.6 Capacity factor improvement: firming intermittent wind generation

12.3 Voltage Regulation: VAR Support on a Wind-dominated Grid

12.3.1 Voltage control of a self-excited induction machine

12.3.2 Voltage regulated VAR control

12.3.3 Typical wind farm PQ operating characteristics

12.3.4 Local voltage change from VAR support

12.3.5 Location of supplying VARs within a wind farm

12.3.6 Self-correcting fault condition: VAR starvation

12.3.7 Efficient-to-use idle wind turbine component capacity for low-voltage VARs

12.3.8 Harmonics and harmonic resonance: location on grid

12.3.9 Islanding, self-correcting conditions and speed of response for VAR controls

12.3.10 Self-correcting fault condition: VAR starvation

12.3.11 Higher-speed grid events: wind turbines that stay connected through grid events

12.3.12 Use of advanced VAR support technologies on weak grids

12.3.13 Load flow studies on a weak grid and with induction machines

12.4 Private Tehachapi Transmission Line

12.5 Conclusions

References

Chapter 13
Wind Power on the Swedish Island of Gotland

By Christer Liljegren and Thomas Ackermann

13.1 Introduction

13.1.1 History

13.1.2 Description of the local power system

13.1.3 Power exchange with the mainland

13.1.4 Wind power in the South of Gotland

13.2 The Voltage Source Converter Based High-voltage Direct-current Solution

13.2.1 Choice of technology

13.2.2 Description

13.2.3 Controllability

13.2.4 Reactive power support and control

13.2.5 Voltage control

13.2.6 Protection philosophy

13.2.7 Losses

13.2.8 Practical experience with the installation

13.2.9 Tjæreborg Project

13.3 Grid Issues

13.3.1 Flicker

13.3.2 Transient phenomena

13.3.3 Stability issues with voltage control equipment

13.3.4 Validation

13.3.5 Power flow

13.3.6 Technical responsibility

13.3.7 Future work

13.4 Conclusions

Further Reading

References

Chapter 14
Isolated Systems with Wind Power

By Per Lundsager and E. Ian Baring-Gould

14.1 Introduction

14.2 Use of Wind Energy in Isolated Power Systems

14.2.1 System concepts and configurations

14.2.2 Basic considerations and constraints for wind–diesel power stations

14.3 Categorisation of Systems

14.4 Systems and Experience

14.4.1 Overview of systems

14.4.2 Hybrid power system experience

14.5 Wind Power Impact on Power Quality

14.5.1 Distribution network voltage levels

14.5.2 System stability and power quality

14.5.3 Power and voltage fluctuations

14.5.4 Power system operation

14.6 System Modelling Requirements

14.6.1 Requirements and applications

14.6.2 Some numerical models for isolated systems

14.7 Application Issues

14.7.1 Cost of energy and economics

14.7.2 Consumer demands in isolated communities

14.7.3 Standards, guidelines and project development approaches

14.8 Conclusions and Recommendations

References

Chapter 15
Wind Farms in Weak Power Networks in India

By Poul Sørensen

15.1 Introduction

15.2 Network Characteristics

15.2.1 Transmission capacity

15.2.2 Steady-state voltage and outages

15.2.3 Frequency

15.2.4 Harmonic and interharmonic distortions

15.2.5 Reactive power consumption

15.2.6 Voltage imbalance

15.3 Wind Turbine Characteristics

15.4 Wind Turbine Influence on Grids

15.4.1 Steady-state voltage

15.4.2 Reactive power consumption

15.4.3 Harmonic and interharmonic emission

15.5 Grid Influence on Wind Turbines

15.5.1 Power performance

15.5.2 Safety

15.5.3 Structural lifetime

15.5.4 Stress on electric components

15.5.5 Reactive power compensation

15.6 Conclusions

References

Chapter 16
Chapter 16: Practical Experience with Power Quality and Wind Power

By Åke Larsson

16.1 Introduction

16.2 Voltage Variations

16.3 Flicker

16.3.1 Continuous operation

16.3.2 Switching operations

16.4 Harmonics

16.5 Transients

16.6 Frequency

16.7 Conclusions

References

Chapter 17
Wind Power Forecast for the German and Danish Networks

By Bernhard Ernst

17.1 Introduction

17.2 Current Development and Use of Wind Power Prediction Tools

17.3 Current Wind Power Prediction Tools

17.3.1 Prediktor

17.3.2 Wind Power Prediction Tool

17.3.3 Zephyr

17.3.4 Previento

17.3.5 eWind

17.3.6 SIPREO´LICO

17.3.7 Advanced Wind Power Prediction Tool

17.3.8 HONEYMOON project

17.4 Conclusions and Outlook

17.4.1 Conclusions

17.4.2 Outlook

References

Useful websites

Chapter 18
Economic Aspects of Wind Power in Power Systems

By Thomas Ackermann and Poul Erik Morthorst

18.1 Introduction

18.2 Costs for Network Connection and Network Upgrading

18.2.1 Shallow connection charges

18.2.2 Deep connection charges

18.2.3 Shallowish connection charges

18.2.4 Discussion of technical network limits

18.2.5 Summary of network interconnection and upgrade costs

18.3 System Operation Costs in a Deregulated Market

18.3.1 Primary control issues

18.3.2 Treatment of system operation costs

18.3.3 Secondary control issues

18.3.4 Electricity market aspects

18.4 Example: Nord Pool

18.4.1 The Nord Pool power exchange

18.4.2 Elspot pricing

18.4.3 Wind power and the power exchange

18.4.4 Wind power and the balancing market

18.5 Conclusions

References

Part C Future Concepts

Chapter 19
Wind Power and Voltage Control

By J. G. Slootweg, S. W. H. de Haan, H. Polinder and W. L. Kling

19.1 Introduction

19.2 Voltage Control

19.2.1 The need for voltage control

19.2.2 Active and reactive power

19.2.3 Impact of wind power on voltage control

19.3 Voltage Control Capabilities of Wind Turbines

19.3.1 Current wind turbine types

19.3.2 Wind turbine voltage control capabilities

19.3.3 Factors affecting voltage control

19.4 Simulation Results

19.4.1 Test system

19.4.2 Steady-state analysis

19.4.3 Dynamic analysis

19.5 Voltage Control Capability and Converter Rating

19.6 Conclusions

References

Chapter 20
Wind Power in Areas with Limited Transmission Capacity

By Julija Matevosyan

20.1 Introduction

20.2 Transmission Limits

20.2.1 Thermal limit

20.2.2 Voltage stability limit

20.2.3 Power output of wind turbines

20.2.4 Transient stability

20.2.5 Summary

20.3 Transmission Capacity: Methods of Determination

20.3.1 Determination of cross-border transmission capacity

20.3.2 Determination of transmission capacity within the country

20.3.3 Summary

20.4 Measures to Increase Transmission Capacity

20.4.1 ‘Soft’ measures

20.4.2 Possible reinforcement measures: thermal limit

20.4.3 Possible reinforcement measures: voltage stability limit

20.4.4 Converting AC transmission lines to DC for higher transmission ratings

20.5 Impact of Wind Generation on Transmission Capacity

20.6 Alternatives to Grid Reinforcement for the Integration of Wind Power

20.6.1 Regulation using existing generation sources

20.6.2 Wind energy spillage

20.6.3 Summary

20.7 Conclusions

References

Chapter 21
Benefits of Active Management of Distribution Systems

By Goran Strbac, Predrag Djapic´, Thomas Bopp and Nick Jenkins

21.1 Background

21.2 Active Management

21.2.1 Voltage-rise effect

21.2.2 Active management control strategies

21.3 Quantification of the Benefits of Active Management

21.3.1 Introduction

21.3.2 Case studies

21.4 Conclusions

References

Chapter 22
Transmission Systems for Offshore Wind Farms

By Thomas Ackermann

22.1 Introduction

22.2 General Electrical Aspects

22.2.1 Offshore substations

22.2.2 Redundancy

22.3 Transmission System to Shore

22.3.1 High-voltage alternating-current transmission

22.3.2 Line-commutated converter based high-voltage direct-current transmission

22.3.3 Voltage source converter based high-voltage direct-current transmission

22.3.4 Comparison

22.4 System Solutions for Offshore Wind Farms

22.4.1 Use of low frequency

22.4.2 DC solutions based on wind turbines with AC generators

22.4.3 DC solutions based on wind turbines with DC generators

22.5 Offshore Grid Systems

22.6 Alternative Transmission Solutions

22.7 Conclusions

Acknowledgement

References

Chapter 23
Hydrogen as a Means of Transporting and Balancing Wind Power Production

By Robert Steinberger-Wilckens

23.1 Introduction

23.2 A Brief Introduction to Hydrogen

23.3 Technology and Efficiency

23.3.1 Hydrogen production

23.3.2 Hydrogen storage

23.3.3 Hydrogen transport

23.4 Reconversion to Electricity: Fuel Cells

23.5 Hydrogen and Wind Energy

23.6 Upgrading Surplus Wind Energy

23.6.1 Hydrogen products

23.7 A Blueprint for a Hydrogen Distribution System

23.7.1 Initial cost estimates

23.8 Conclusions

References

Part D Dynamic Modelling of Wind Turbines for power System Studies

Chapter 24
Introduction to the Modelling of Wind Turbines 525

By Hans Knudsen and Jørgen Nygård Nielsen

24.1 Introduction

24.2 Basic Considerations regarding Modelling and Simulations

24.3 Overview of Aerodynamic Modelling

24.3.1 Basic description of the turbine rotor

24.3.2 Different representations of the turbine rotor

24.4 Basic Modelling Block Description of Wind Turbines

24.4.1 Aerodynamic system

24.4.2 Mechanical system

24.4.3 Generator drive concepts

24.4.4 Pitch servo

24.4.5 Main control system

24.4.6 Protection systems and relays

24.5 Per Unit Systems and Data for the Mechanical System

24.6 Different Types of Simulation and Requirements for Accuracy

24.6.1 Simulation work and required modelling accuracy

24.6.2 Different types of simulation

24.7 Conclusions

References

Chapter 25
Reduced-order Modelling of Wind Turbines

By J. G. Slootweg, H. Polinder and W. L. Kling

25.1 Introduction

25.2 Power System Dynamics Simulation

25.3 Current Wind Turbine Types

25.4 Modelling Assumptions

25.5 Model of a Constant-speed Wind Turbine

25.5.1 Model structure

25.5.2 Wind speed model

25.5.3 Rotor model

25.5.4 Shaft model

25.5.5 Generator model

25.6 Model of a Wind Turbine with a Doubly fed Induction Generator

25.6.1 Model structure

25.6.2 Rotor model

25.6.3 Generator model

25.6.4 Converter model

25.6.5 Protection system model

25.6.6 Rotor speed controller model

25.6.7 Pitch angle controller model

25.6.8 Terminal voltage controller model

25.7 Model of a Direct drive Wind Turbine

25.7.1 Generator model

25.7.2 Voltage controller model

25.8 Model Validation

25.8.1 Measured and simulated model response

25.8.2 Comparison of measurements and simulations

25.9 Conclusions

References

Chapter 26
High-order Models of Doubly-fed Induction Generators

By Eva Centeno Lopez and Jonas Persson

26.1 Introduction

26.2 Advantages of Using a Doubly-fed Induction Generator

26.3 The Components of a Doubly-fed Induction Generator

26.4 Machine Equations

26.4.1 The vector method

26.4.2 Notation of quantities

26.4.3 Voltage equations of the machine

26.4.4 Flux equations of the machine

26.4.5 Mechanical equations of the machine

26.4.6 Mechanical equations of the wind turbine

26.5 Voltage Source Converter

26.6 Sequencer

26.7 Simulation of the Doubly fed Induction Generator

26.8 Reducing the Order of the Doubly fed Induction Generator

26.9 Conclusions

References

Chapter 27
Full-scale Verification of Dynamic Wind Turbine Models

By Vladislav Akhmatov

27.1 Introduction

27.1.1 Background

27.1.2 Process of validation

27.2 Partial Validation

27.2.1 Induction generator model

27.2.2 Shaft system model

27.2.3 Aerodynamic rotor model

27.2.4 Summary of partial validation

27.3 Full-scale Validation

27.3.1 Experiment outline

27.3.2 Measured behaviour

27.3.3 Modelling case

27.3.4 Model validation

27.3.5 Discrepancies between model and measurements

27.4 Conclusions

References

Chapter 28
Impacts of Wind Power on Power System Dynamics

By J. G. Slootweg and W. L. Kling

28.1 Introduction

28.2 Power System Dynamics

28.3 Actual Wind Turbine Types

28.4 Impact of Wind Power on Transient Stability

28.4.1 Dynamic behaviour of wind turbine types

28.4.2 Dynamic behaviour of wind farms

28.4.3 Simulation results

28.5 Impact of Wind Power on Small Signal Stability

28.5.1 Eigenvalue–frequency domain analysis

28.5.2 Analysis of the impact of wind power on small signal stability

28.5.3 Simulation results

28.5.4 Preliminary conclusions

28.6 Conclusions

References

Chapter 29
Aggregated Modelling and Transient Voltage Stability of Large Wind Farms

By Vladislav Akhmatov

29.1 Introduction

29.1.1 Main outline

29.1.2 Area of application

29.1.3 Additional requirements

29.2 Large Wind Farm Model

29.2.1 Reactive power conditions

29.2.2 Faulting conditions

29.3 Fixed-speed Wind Turbines

29.3.1 Wind turbine parameters

29.3.2 Stabilisation through power ramp

29.4 Wind Turbines with Variable Rotor Resistance

29.5 Variable-speed Wind Turbines with Doubly-fed Induction Generators

29.5.1 Blocking and restart of converter

29.5.2 Response of a large wind farm

29.6 Variable-speed Wind Turbines with Permanent Magnet Generators 6

29.7 A Single Machine Equivalent

29.8 Conclusions

References

Index

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