Power improvement of non-linear wind turbines during partial load operation using fuzzy inference control

Abstract

Power generation in modern and industrial wind turbines can be improved by careful choice and analysis of operational control strategies. In this paper a new controller scheme is proposed in partial load operation of the wind turbine where the pitch angle is kept constant at zero and the generator torque is adjusted utilizing the fuzzy inference method. Fuzzy rules were defined with respect to the response of the wind turbine to reference gains such that the output power tracks the ideal power curve as close as possible without any significant increase of stress on the main shaft and drive train. A variety of membership shape functions were considered to show the resulting effect on the extracted energy and the drive train stress. Accordingly, through numerous simulations, it can be seen that the total harvested energy is increased. The fuzzy controller was evaluated based on a nonlinear model of the wind turbine using real wind speed applied to the model as a disturbance, to consider the practicality of the proposed controller.