Introduction to Wind Energy Systems (eBook)

Hermann-Josef Wagner is Professor for Energy Systems and Energy Economics at the Ruhr-University of Bochum, Germany. He worked as a scientist for the Research Centre Juelich, for the German Parliament and for different universities. His relevant experiences are on the fields on energy systems analysis, renewable energies like wind energy and life cycle analysis.  Dr.-Ing. Jyotirmay Mathur is a mechanical engineer postgraduate in energy studies from Indian Institute of Technology, Delhi, India; and doctorate from University of Essen, Germany. He specializes in the areas of renewable energy systems, energy policy modelling and energy efficiency. Working as Reader in the Malaviya National Institute of Technology in Jaipur, Dr. Mathur has been founder coordinator of the postgraduate program in energy engineering. He is involved with several committees of national importance in India.

Preface 5
Contents 6
List of Figures 9
List of Tables 11
About the Authors 12
1 Wind Energy Today 13
1.1 Status 13
1.2 Advantages and Disadvantages of Wind Energy Systems 14
1.2.1 Advantages 15
1.2.2 Disadvantages 15
1.3 Different Types of Wind Energy Converters: An Overview 15
2 Wind: Origin and Local Effects 19
2.1 Origin and Global Availability 19
2.2 Local Effects on Wind Flow 19
2.3 Attractive Locations for Wind Energy 21
2.4 Local Effects on Wind Flow 22
2.4.1 Roughness Length and Wind Shear 22
2.4.2 Wind Speed Variability 22
2.4.3 Turbulence 23
2.4.4 Obstacles to Wind Flow 24
2.4.5 The Wind Wake and Park Effect 25
2.4.6 The Hill Effect and Tunnel Effect 25
2.5 Selecting a Turbine Site 26
3 Physics of Wind Energy 28
3.1 Energy Content in Wind 28
3.2 Energy Conversion at the Blade 30
3.3 Power Coefficients and Principles of Design 32
3.3.1 Coefficient of Power c p and Betz' Law 32
3.3.2 Tip Speed Ratio 33
3.3.3 Power Efficiency 33
3.3.4 Principles of Design 35
3.4 Wind Variations 35
3.4.1 Wind Shear with Height 35
3.4.2 Influence of Weibull Distribution 37
4 Components of a Wind Energy Converter 40
4.1 Rotor Blades 40
4.2 Gearboxes 42
4.3 Generators 43
4.3.1 Generating Voltage generating voltage 43
4.3.2 Generator Cooling System 43
4.3.3 Generator Rotational Speed 43
4.3.4 Two Speed, Pole Changing Generators 45
4.4 Towers 45
4.5 Miscellaneous Components 46
5 Design Considerations 51
5.1 Rotor Area of Turbines 51
5.1.1 Reasons for Choosing Large Turbines 51
5.1.2 Reasons for Choosing Smaller Turbines 51
5.2 Number of Blades 52
5.3 Horizontal or Vertical Axis Turbine 53
5.4 Upwind upwind or Downwind Turbine 55
5.5 Load Considerations for Turbine Selection 56
5.6 Wind Turbines: With or Without Gearbox 57
5.7 Requirement of Grid, Synchronous or Asynchronous Generators 59
5.8 Issue of Noise and Its Control 63
6 Operation and Control of Wind Energy Converters 66
6.1 Power Curve and Capacity Factor 66
6.1.1 Power Curve 66
6.1.2 Capacity Factor 67
6.2 Power Control of Wind Turbines 68
6.2.1 Pitch Control 69
6.2.1.1 Running a Pitch Controlled Turbine at Variable Speed 70
6.2.2 Stall Control 71
6.2.2.1 Passive Stall Control 71
6.2.2.2 Active Stall Control 72
6.2.3 The Yaw Control 72
6.3 Connection to the Grid 73
6.3.1 Applications of Wind Energy Converters 73
6.3.2 Voltage Requirement 74
6.3.3 Special Aspects of the Connection of Offshore Wind Parks 74
7 Economics and Policy Issues 77
7.1 Cost of Wind Turbines cost of wind turbine 77
7.1.1 Initial Cost of Wind Turbine 77
7.1.2 Operation and Maintenance Costs for Wind Turbines 78
7.1.2.1 Operation Maintenance Costs 78
7.1.2.2 Turbine Reinvestment (Refurbishment, Major Overhauls) 78
7.1.2.3 The Availability Factor availability factor 79
7.2 Electrical Tariffs 79
7.3 Mechanisms to Support Funding 81
7.3.1 Capacity Credit 81
7.3.2 Environmental Credit environmental credit and Clear Development Mechanism 82
7.3.3 Tax Benefits tax benefit 82
7.4 Wind Energy Economics 82
7.4.1 Financial Analysis -- A Case Study for India 83
7.4.2 Financing financing of a Wind Park -- A Case in Germany 83
7.5 Wind Turbines After Operational Life 85
8 Outlook 86
Glossary 87
Literature 88
Index 89