POWER ADVANCES IN WIND Edited by Rupp Carriveau ADVANCES IN WIND POWER Edited by Rupp Carriveau Advances in Wind Power http://dx.doi.org/10.5772/3376 Edited by Rupp Carriveau Contributors Hengameh Kojooyan Jafari, Mostafa Abarzadeh, Hossein Madadi Kojabadi, Liuchen Chang, Daniel MATT, Emilio Gomez-Lazaro, Sergio Martín Martínez, Angel Molina-Garcia, Antonio Vigueras Rodriguez, Michael Milligan, Eduard Muljadi, Adrian Ilinca, David Wood, Ed Nowicki, Mohamed Fahmy Aner, Samer El Itani, Géza Joós, Mahmoud Huleihil, Karam Youssef Maalawi, Fernando Ponta, Alejandro Otero, Lucas Ignacio Lago, Wenping Cao, Ying Xie, Zheng Tan, Horizon Gitano, João Paulo Vieira, Rupp Carriveau, Tim Newson, Philip McKay, David S-K Ting Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. 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Publishing Process Manager Iva Simcic Technical Editor InTech DTP team Cover InTech Design team First published November, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from orders@intechopen.com Advances in Wind Power, Edited by Rupp Carriveau p. cm. ISBN 978-953-51-0863-4 Contents Preface VII Section 1 Inflow and Wake Influences on Turbine Performance 1 Chapter 1 Wind Turbine Power: The Betz Limit and Beyond 3 Mahmoud Huleihil and Gedalya Mazor Chapter 2 Effect of Turbulence on Fixed-Speed Wind Generators 31 Hengameh Kojooyan Jafari Chapter 3 Turbine Wake Dynamics 65 Phillip McKay, Rupp Carriveau, David S-K Ting and Timothy Newson Section 2 Turbine Structural Response 85 Chapter 4 Aeroelasticity of Wind Turbines Blades Using Numerical Simulation 87 Drishtysingh Ramdenee, Adrian Ilinca and Ion Sorin Minea Chapter 5 Structural Analysis of Complex Wind Turbine Blades: Flexo- Torsional Vibrational Modes 123 Alejandro D. Otero, Fernando L. Ponta and Lucas I. Lago Section 3 Power Conversion, Control, and Integration 151 Chapter 6 Recent Advances in Converters and Control Systems for Grid- Connected Small Wind Turbines 153 Mohamed Aner, Edwin Nowicki and David Wood Chapter 7 Wind Turbine Generator Technologies 177 Wenping Cao, Ying Xie and Zheng Tan Chapter 8 A Model for Dynamic Optimization of Pitch-Regulated Wind Turbines with Application 205 Karam Y. Maalawi Chapter 9 Comparative Analysis of DFIG Based Wind Farms Control Mode on Long-Term Voltage Stability 225 Rafael Rorato Londero, João Paulo A. Vieira and Carolina de M. Affonso Chapter 10 Design of a Mean Power Wind Conversion Chain with a Magnetic Speed Multiplier 247 Daniel Matt, Julien Jac and Nicolas Ziegler Chapter 11 Low Speed Wind Turbine Design 267 Horizon Gitano-Briggs Chapter 12 Wind Power Variability and Singular Events 285 Sergio Martin-Martínez, Antonio Vigueras-Rodríguez, Emilio Gómez-Lázaro, Angel Molina-García, Eduard Muljadi and Michael Milligan Chapter 13 Power Electronics in Small Scale Wind Turbine Systems 305 Mostafa Abarzadeh, Hossein Madadi Kojabadi and Liuchen Chang Chapter 14 Advanced Wind Generator Controls: Meeting the Evolving Grid Interconnection Requirements 337 Samer El Itani and Géza Joós ContentsVI Preface Today’s wind energy industry is at a crossroads. Global economic instability has threatened or eliminated many financial incentives that have been important to the development of specific markets. Such economic sponsorship of energy generation is not unique to renewables; fossil based sources are also subsidized in many different countries. However, for a technology like wind energy whose markets are still developing, incentives can be critical for industry growth. Industry proponents have decreed that long-term energy policy that survives financial swings and changes in government is what is needed to provide the stability that market investors seek. While this may be the case, in the mean time, the pressure is on wind industry designers, manufacturers, and operators to seek the most effectual measures for wind power production. Like the wind itself, the industry operates on large and small scales. While large commercial wind has traditionally received the most coverage in the literature and the media, small wind has recently established itself as a major player in distributed energy systems. This will become increasingly important as micro grids rapidly find their place in both the developed and developing worlds. In urban and isolated rural settings, small wind is growing rapidly. It is important to emphasize this multi-scale resilience that wind generation provides as an energy solution. The broad range of scales within wind energy is only surpassed by the expansive scope of technologies that cover the spectrum from resource assessment to grid integration. Specialized sub-topics continue to emerge that provide focus for improving critical links in the wind chain. This sort of specificity can be vital for isolating technical elements from the complexity of interconnected wind energy systems. A brief list of emerging specific interest fields include aerodynamic interaction of wind turbine groups, computational modeling of complex composite blades, magnetic speed multiplying converters, generator controls optimized for small wind, disturbance tolerant generators, micro and smart grid integration. This text details topics fundamental to the efficient operation of modern commercial farms and highlights advanced research that will enable next-generation wind energy technologies. The book is organized into three sections, Inflow and Wake Influences on Turbine Performance, Turbine Structural Response, and Power Conversion, Control and Integration. In addition to fundamental concepts, the reader will be exposed to comprehensive treatments of topics like wake dynamics, analysis of complex turbine blades, and power electronics in small-scale wind turbine systems. Dr. Rupp Carriveau Department of Civil and Environmental Engineering, Windsor, Canada Section 1 Inflow and Wake Influences on Turbine Performance [...]... feasibility of wind turbine installation was presented, and the potential of wind power generation was statistically analyzed [12] 1.5 Types of wind turbines There are different types of wind turbines: bare wind turbines, augmented wind turbines, horizontal axis wind turbines, and vertical axis wind turbines, just to mention a few 1.5.1 Bare wind turbines According to research findings as given by [13],... numerical simulation tools for wind turbine rotors and wakes were reviewed, in cluding rotor predictions as well as models for simulating wind turbine wakes and flows in wind farms [3] 1.3 Wind power density Concerning power density and its relation to wind speed, the report given in [4] pre‐ sented the features of wind power distributions that were analytically obtained from wind distribution functions... within more realistic limits, including an approximate limit to the maximum power from a wind turbine, was obtained In addition, different equations were obtained establishing relationships between mean power density and mean wind speed These equations are simple and useful when discarding locations for wind tur‐ bine installation [4] 1.4 Wind power applications The range of wind power usage is scarce One... establishing a relationship between mean power density and wind speed have been obtained for a given location and wind tur‐ bine Different concepts relating to wind power distribution functions were shown— among them the power transported by the wind and the theoretical maximum converti‐ ble power from wind, according to the Betz’ law Maximum convertible power from the wind was explained within more... coefficient CF, with different values 4 Wind turbine arrangements One could suggest ideas to increase power extraction from the wind, thus decreasing the overall cost One suggestion is the bottoming wind turbine; another is the flower leaves ar‐ rangement of wind turbines Both are discussed in the following sections 4.1 Bottoming wind turbines According to Betz, the maximal power extraction efficiency is 16/27... of a wind turbine was introduced [41] and the efficiency at maximum power output ηmp was derived Although the power de‐ veloped in a wind turbine derives from kinetic energy rather than from heat, it was possible to view the basic model of the wind turbine in a schematic way, which is similar to the heat engine picture After the wind turbine accepts energy input in its upstream side, it extracts power. .. highlighted by [2], wind provides an inter‐ mittent but environmentally friendly energy source that does not pollute atmosphere Wind power calculations are initiated from the kinetic energy definition, and wind power is found to be proportional to half the air density multiplied by the cube of the wind velocity When seeking to determine the potential usage of wind energy, wind power formulation is... attractiveness of this idea is to gain more output with the same tower installation, reducing the inherently larger cost of erecting multiple towers 23 24 Advances in Wind Power 4.2 Flower leaves arrangement of wind turbines Considering the shrouded wind turbine as being a relatively small device is given (some‐ times called flower power while searching the web), one could suggest installing different devices on... many wind turbines together, several issues should be considered [33] Other research studies discussed the issue of optimizing the placement of wind turbines in wind farms [34] Factors consid‐ ered included multidirectional winds and variable wind speeds, the effect of ambient turbu‐ lence in the wake recovery, the effect of ground, variable hub height of the wind turbines, and different terrains [34]... the bottoming wind turbine, the attractiveness of the flower leaves configuration is that many small‐ er turbines can be accommodated on a single tower, with significant cost reductions 5 Summary and conclusions In this study, wind turbine power was reconsidered At the beginning, a literature review was given with relation to the potentiality of wind power, worldwide applications of wind power, and . POWER ADVANCES IN WIND Edited by Rupp Carriveau ADVANCES IN WIND POWER Edited by Rupp Carriveau Advances in Wind Power http://dx.doi.org/10.5772/3376 Edited. [12]. 1.5. Types of wind turbines There are different types of wind turbines: bare wind turbines, augmented wind turbines, horizontal axis wind turbines, and vertical