PITCH CONTROL FOR WIND TURBINE IN YAWED INFLOW CONDITION

A wind turbine can experience yawed inflow with large yaw misalignment angle during faulty cases, such as faults in the yaw controller/drives, or during extreme atmospheric cases, such as thunderstorm downbursts. In such cases, it is risky for the turbine to continue operation because it is being exposed to large loads. Instead, it is recommended for the turbine to be transited to parking conditions. Currently, most turbine pitch controllers are designed without considering the yaw misalignment angle, correction of which is normally assigned to the yaw controller This paper investigates the contribution of both a baseline and a proposed collective pitch controllers under yawed inflow conditions. The baseline controller tries to maintain the rated operating condition at an expense of large blade loads. On the contrary, simulation results show that the proposed controller slows down the turbine under the presence of yawed inflow, which helps to park the turbine and reduces the average blade root bending moments.