Wind Energy Handbook

Fully updated and authoritative reference to wind energy technology written by leading academic and industry professionals The newly revised Third Edition of the Wind Energy Handbook delivers a fully updated treatment of key developments in wind technology since the publication of the book's Second Edition in 2011. The criticality of wakes within wind farms is addressed by the addition of an entirely new chapter on wake effects, including 'engineering' wake models and wake control. Offshore, attention is focused for the first time on the design of floating support structures, and the new 'PISA' method for monopile geotechnical design is introduced. The coverage of blade design has been completely rewritten, with an expanded description of laminate fatigue properties and new sections on manufacturing methods, blade testing, leading-edge erosion and bend-twist coupling. These are complemented by new sections on blade add-ons and noise in the aerodynamics chapters, which now also include a description of the Leishman-Beddoes dynamic stall model and an extended introduction to Computational Fluid Dynamics analysis. The importance of the environmental impact of wind farms both on- and offshore is recognized by expanded coverage, and the requirements of the Grid Codes to ensure wind energy plays its full role in the power system are described. The conceptual design chapter has been extended to include a number of novel concepts, including low induction rotors, multiple rotor structures, superconducting generators and magnetic gearboxes. References and further reading resources are included throughout the book and have been updated to cover the latest literature. As in previous editions, the core subjects constituting the essential background to wind turbine and wind farm design are covered. These include: The nature of the wind resource, including geographical variation, synoptic and diurnal variations, and turbulence characteristics The aerodynamics of horizontal axis wind turbines, including the actuator disc concept, rotor disc theory, the vortex cylinder model of the actuator disc and the Blade-Element/Momentum theory Design loads for horizontal axis wind turbines, including the prescriptions of international standards Alternative machine architectures The design of key components Wind turbine controller design for fixed and variable speed machines The integration of wind farms into the electrical power system Wind farm design, siting constraints, and the assessment of environmental impact Perfect for engineers and scientists learning about wind turbine technology, the Wind Energy Handbook will also earn a place in the libraries of graduate students taking courses on wind turbines and wind energy, as well as industry professionals whose work requires a deep understanding of wind energy technology.

Table of Contents:
About the Authors xxi Preface to Second Edition xxiii Preface to Third Edition xxv Acknowledgements for the First Edition xxix Acknowledgements for the Second Edition xxxi Acknowledgements for the Third Edition xxxiii List of Symbols xxxv Figures C1 and C2 -- coordinate systems xlv 1 Introduction 1 1.1 Historical development of wind energy 1 1.2 Modern wind turbines 6 1.3 Scope of the book 8 2 The wind resource 11 2.1 The nature of the wind 11 2.2 Geographical variation in the wind resource 13 2.3 Long-term wind speed variations 14 2.4 Annual and seasonal variations 14 2.5 Synoptic and diurnal variations 16 2.6 Turbulence 16 2.7 Gust wind speeds 30 2.8 Extreme wind speeds 31 2.9 Wind speed prediction and forecasting 35 2.10 Turbulence in complex terrain 37 3 Aerodynamics of horizontal axis wind turbines 39 3.1 Introduction 40 3.2 The actuator disc concept 41 3.3 Rotor disc theory 45 3.4 Vortex cylinder model of the actuator disc 49 3.5 Rotor blade theory (blade-element/momentum theory) 59 3.6 Actuator line theory, including radial variation 65 3.7 Breakdown of the momentum theory 66 3.8 Blade geometry 68 3.9 The effects of a discrete number of blades 77 3.10 Stall delay 92 3.11 Calculated results for an actual turbine 95 3.12 The performance curves 98 3.13 Constant rotational speed operation 102 3.14 Pitch regulation 106 3.15 Comparison of measured with theoretical performance 107 3.16 Estimation of energy capture 109 3.17 Wind turbine aerofoil design 113 3.18 Add-ons (including blade modifications independent of the main structure) 121 3.19 Aerodynamic noise 126 Appendix A.3 Lift and drag of aerofoils 133 A3.1 Drag 134 A3.2 The boundary layer 135 A3.3 Boundary layer separation 136 A3.4 Laminar and turbulent boundary layers and transition 138 A3.5 Definition of lift and its relationship to circulation 141 A3.6 The stalled aerofoil 145 A3.7 The lift coefficient 145 A3.8 Aerofoil drag characteristics 147 4 Further aerodynamic topics for wind turbines 153 4.1 Introduction 153 4.2 The aerodynamics of turbines in steady yaw 153 4.3 Circular wing theory applied to a rotor in yaw 180 4.4 Unsteady flow 189 4.5 Unsteady aerofoil aerodynamics 194 4.6 Dynamic stall 201 4.7 Computational fluid dynamics 207 5 Design loads for HAWTs 227 5.1 National and international standards 227 5.2 Basis for design loads 228 5.3 Turbulence and wakes 231 5.4 Extreme loads 233 5.5 Fatigue loading 240 5.6 Stationary blade loading 240 5.7 Blade loads during operation 248 5.8 Blade dynamic response 277 5.9 Blade fatigue stresses 302 5.10 Hub and low-speed shaft loading 309 5.11 Nacelle loading 312 5.12 Tower loading 315 5.13 Wind turbine dynamic analysis codes 325 5.14 Extrapolation of extreme loads from simulations 331 Appendix A.5 Dynamic response of stationary blade in turbulent wind 345 A5.1 Introduction 345 A5.2 Frequency response function 345 A5.3 Resonant displacement response ignoring wind variations along the blade 347 A5.4 Effect of across wind turbulence distribution on resonant displacement response 349 A5.5 Resonant root bending moment 352 A5.6 Root bending moment background response 354 A5.7 Peak response 355 A5.8 Bending moments at intermediate blade positions 358 6 Conceptual design of horizontal axis wind turbines 361 6.1 Introduction 361 6.2 Rotor diameter 361 6.3 Machine rating 370 6.4 Rotational speed 375 6.5 Number of blades 379 6.6 Teetering 388 6.7 Power control 391 6.8 Braking systems 398 6.9 Fixed-speed, two-speed, variable-slip, and variable-speed operation 400 6.10 Other drive trains and generators 411 6.11 Drive train mounting arrangement options 419 6.12 Drive train compliance 425 6.13 Rotor position with respect to tower 426 6.14 Tower stiffness 427 6.15 Multiple rotor structures 430 6.16 Augmented flow 435 6.17 Personnel safety and access issues 435 7 Component design 441 7.1 Blades 441 7.2 Pitch bearings 519 7.3 Rotor hub 521 7.4 Gearbox 524 7.5 Generator 537 7.6 Mechanical brake 548 7.7 Nacelle bedplate 555 7.8 Yaw drive 555 7.9 Tower 558 7.10 Foundations 570 8 The controller 579 8.1 Functions of the wind turbine controller 580 8.2 Closed-loop control: issues and objectives 583 8.3 Closed-loop control: general techniques 589 8.4 Closed-loop control: analytical design methods 617 8.5 Pitch actuators 629 8.6 Control system implementation 631 9 Wake effects and wind farm control 637 9.1 Introduction 637 9.2 Wake characteristics 638 9.3 Active wake control methods 652 9.4 Wind farm control and the grid system 658 10 Onshore wind turbine installations and wind farms 665 10.1 Project development 666 10.2 Landscape and visual impact assessment 678 10.3 Noise 687 10.4 Electromagnetic interference 698 10.5 Ecological assessment 706 11 Wind energy and the electric power system 717 11.1 Introduction 717 11.2 Wind turbine electrical systems 721 11.3 Wind farm electrical systems 730 11.4 Connection of wind farms to distribution networks 735 11.5 Grid codes and the connection of large wind farms to transmission networks 742 11.6 Wind energy and the generation system 750 11.7 Power quality 756 Appendix A.11 Simple calculations for the connection of wind turbines 766 A11.1 The per-unit system 766 A11.2 Power flows, slow voltage variations, and network losses 767 12 Offshore wind turbines and wind farms 771 12.1 Offshore wind farms 771 12.2 The offshore wind resource 776 12.3 Design loads 781 12.4 Machine size optimisation 822 12.5 Reliability of offshore wind turbines 824 12.6 Fixed support structures -- overview 828 12.7 Fixed support structures 829 12.8 Floating support structures 883 12.9 Environmental assessment of offshore wind farms 908 12.10 Offshore power collection and transmission systems 913 References 922 Appendix A.12 Costs of electricity 931 A12.1 Levelised cost of electricity 931 A12.2 Strike price and contract for difference 931 Index 933