A General Description and Comparison of Horizontal Axis Wind Turbines and Vertical Axis Wind Turbines Margrét Ósk Óskarsdóttir Faculty of Industrial Engineering, Mechanical Engineering and Computer Science University of Iceland 2014 A General Description and Comparison of Horizontal Axis Wind Turbines and Vertical Axis Wind Turbines Margrét Ósk Óskarsdóttir 30 ECTS thesis submitted in partial fulfillment of a Magister Scientiarum degree in Mechanical Engineering Advisors Rúnar Unnþórsson Magnús Þór Jónsson Faculty Representative Sæþór Ásgeirsson Faculty of Industrial Engineering, Mechanical Engineering and Computer Science School of Engineering and Natural Sciences University of Iceland Reykjavik, October 2014 A General Description and Comparison of Horizontal Axis Wind Turbines and Vertical Axis Wind Turbines Comparison of HAWT and VAWT 30 ECTS thesis submitted in partial fulfillment of a Magister Scientiarum degree in Mechanical Engineering Copyright © 2014 Margrét Ósk Óskarsdóttir All rights reserved Faculty of Industrial Engineering, Mechanical Engineering and Computer Science School of Engineering and Natural Sciences University of Iceland Hjardarhagi 2-6 101 Reykjavik, Reykjavik Iceland Telephone: 525 4000 Bibliographic information: Margrét Ósk Óskarsdóttir, 2014, A General Description and Comparison of Horizontal Axis Wind Turbine and Vertical Axis Wind Turbine, Master’s thesis, Faculty of Industrial Engineering, Mechanical Engineering and Computer Science, University of Iceland, pp. 130. Printing: Háskólaprent, Fálkagata 1, 107 Reykjavik Reykjavik, Iceland, October 2014 Abstract This master thesis is a general description and comparison of horizontal axis wind turbines and vertical axis wind turbines. Main components of horizontal axis wind turbine are covered. Vertical axis wind turbines are presented along with various sub-types. The design procedure is covered with emphasis on the layout of the wind turbine, both horizontal and vertical. Next, a description of different wind farm layouts is covered along with studies on the subject. Finally, a short description on a decision making process is shown in how to choose the right wind turbine or turbines for certain cases. A simple diagram leads the customer through the decision making process, answering what wind turbine or turbines are best suitable according to the customer’s needs. The diagram is also a foundation for designing a software program, which could link to desirable wind turbines available from an existing database. Útdráttur Þetta meistaraverkefni er heimildaritgerð á vindmyllum. Fjallað er um helstu íhluti vindmylla sem hafa rótor með láréttan ás. Þar á eftir eru teknar fyrir helstu gerðir rótora sem hafa lóðréttan ás og nokkrar undirgerðir þeirra. Þá er fjallað um hönnunarferlið með áherslu á hönnun vindmyllunnar. Þar voru einnig bornar saman vindmyllur út frá ás rótors í því samhengi. Gerð voru skil á vindmyllugörðum, mismunandi aðferðafræði og rannsóknir sem hafa verið gerðar á uppbyggingu þeirra. Að lokum er stutt lýsing á ákvarðanaferli um hvernig velja eigi réttu vindmylluna fyrir ákveðin tilfelli með þarfir viðskiptavinar í huga. Gerð var einföld mynd sem leiðir notandann í gegnum ákvarðanaferlið sem að lokum gefur niðurstöðu út frá þörfum hans. Það er auðvelt að bæta við myndina ef þurfa þykir. Myndin er einnig góður grunnur að því að hanna forrit sem gæfi þá ákjósanlega niðurstöðu. Forritið myndi þannig þjóna þeim tilgangi að finna vindmylluna/vindmyllurnar sem henta út frá gagnagrunni sem þá væri til staðar. Table of Contents List of Figures ................................................................................................................... viii List of Tables ........................................................................................................................ x List of Symbols .................................................................................................................... xi Acknowledgements ........................................................................................................... xiii 1 Introduction ................................................................................................................... 15 1.1 Contributions ......................................................................................................... 16 1.2 Structure of the Thesis ........................................................................................... 17 2 Theoretical Background of Wind Turbines ............................................................... 19 2.1 The Betz Law ........................................................................................................ 19 2.2 Tip Speed Ratio ..................................................................................................... 21 2.3 Power Curve .......................................................................................................... 23 2.4 Lift and Drag Forces .............................................................................................. 24 2.5 Friction .................................................................................................................. 25 2.6 Turbulence ............................................................................................................. 25 2.7 Angle of Attack ..................................................................................................... 27 2.8 Twist Angle ........................................................................................................... 27 2.9 Pitch Angle ............................................................................................................ 27 3 Horizontal Axis Wind Turbines .................................................................................. 29 3.1 Tower ..................................................................................................................... 30 3.2 Foundation ............................................................................................................. 33 3.3 Rotor ...................................................................................................................... 34 3.4 Rotor Blades .......................................................................................................... 36 3.4.1 Aerodynamics .............................................................................................. 36 3.4.2 Angle of Twist, Angle of Attack and Pitch Angle ....................................... 36 3.4.3 Tip Speed Ratio............................................................................................ 37 3.4.4 Blade Plan Shape and Quantity .................................................................... 38 3.5 Rotor Hub .............................................................................................................. 40 3.6 Control System ...................................................................................................... 40 3.6.1 Pitch Control System ................................................................................... 41 3.6.2 Yaw Control System .................................................................................... 41 3.6.3 Stall Regulation ............................................................................................ 41 3.7 Anemometer .......................................................................................................... 42 3.8 Gear Box ................................................................................................................ 43 3.9 Nacelle ................................................................................................................... 44 3.10 Heat Exchanger ..................................................................................................... 44 3.11 Brake Mechanism .................................................................................................. 45 3.11.1 Aerodynamic Braking System ..................................................................... 45 3.11.2 Mechanical Braking System ........................................................................ 45 v 3.12 Low-Speed Shaft and High-speed shaft ................................................................. 46 3.13 Electrical Generator ............................................................................................... 46 3.13.1 Induction Generators ................................................................................... 46 3.13.2 Synchronous Generators .............................................................................. 47 3.14 Yaw System ........................................................................................................... 47 3.14.1 Yaw Bearing ................................................................................................ 48 3.14.2 Yaw Motor ................................................................................................... 48 3.14.3 Yaw Drive .................................................................................................... 48 4 Vertical Axis Wind Turbines ........................................................................................ 51 4.1 The Savonius Rotor ................................................................................................ 53 4.2 The Darrieus Vertical Wind Turbine ..................................................................... 54 4.3 The H-Darrieus Rotor