Design Optimization of Small Wind Turbines for Low Wind Regimes

The optimized design of a wind turbine depends on numerous parameters involving the entire machine (rotor, generator, etc.) and on the intended operating environment as described by the wind characteristics as well as on the load or application. This paper presents the design optimization process, identifies and discusses the influence of the various parameters, and then reviews the procedure by looking at two examples. The results of this process emphasize the relative importance of the design on rated wind speed, rotor rpm, generator size, and rotor blade characteristics. These results in general show that wind turbines have been designed for excessively high-rated wind speeds and generator capacities, except for those machines intended for wind farm applications and sites with particularly high winds. Machines designed for residential use should be sized to closely match the expected load and should be rated at a wind speed close to that value where the maximum energy contribution occurs. This wind speed is much lower than the rated wind speed for most currently available machines particularly for regions of relatively low annual mean wind speeds. Simplicity of design leads to a lower cost system, lower maintenance, and operating costs and greater reliability. It is this simply designed and optimized wind turbine that will have lasting success in the commercial market place.