Maximal power extraction strategy in the transition region and its benefit on the AEP (annul energy product)

The rotational speed of a wind turbine is limited by the noise constraint of the blade tip speed. The larger the rotor diameter is, the smaller the rotor speed becomes. Therefore, there exists a transition region connecting the max-Cp operation with the power regulation operation. A conventional pitch schedule in this region involves using a fixed pitch. However, if the variable pitch instead of the fixed one is allowed, more electric power can be extracted from the wind. The benefit of using this strategy is analyzed from the point of how much the electric energy can be gained by applying the variable pitch schedule in this transition region.