ABSTRACT
The power coefficient Cp is the product of the mechanical efficiency ηm the electrical efficiency ηe and the aerodynamic efficiency. All three factors are dependent on the wind speed and the produced power. The air density can be calculated from air temperature and pressure. Power curves are sometimes referenced to 'standard conditions' corresponding to sea level pressure and a mean air temperature of 15ºC. For a particular wind turbine, power production is specified by the power curve. The wind speed at a meteorological station or wind turbine site is determined mainly by two factors: the overall weather systems and the nearby topography out to a few tens of kilometers from the site. In the European Wind Atlas a comprehensive set of models for the horizontal and vertical extrapolation of meteorological data and the estimation of wind resources were developed; these are implemented in the WAsP PC program (Wind Atlas Analysis and Application Program).
