Considering induction factor using BEM method in wind farm layout optimization

For wind farm layout optimization process, a simple linear model has been mostly used for considering the wake effect of a wind turbine on its downstream turbines. In this model, the wind velocity in the wake behind a turbine is obtained as a function of turbine induction factor which was considered to be 0.324 almost in all the previous studies. However, it is obviously evident that this factor is a strong function of turbine blade geometry and operational conditions. In the present study, a new method is introduced by which the induction factor for wind turbines can be calculated based on the method of Blade Element Momentum theory. By this method, the effect of blade profile, wind speed and angular velocity of wind turbine on the induction factor can be easily taken into account. The results show that for different blade profiles and operational conditions, the induction factor differs from the single value used so far. Also it is shown that this difference has a very significant effect in calculated gained power from a wind farm. It is clearly seen that considering the new method for calculating an appropriate induction factor affects the total calculated power generation of a wind farm and consequently influences the farm layout in optimization process.