Torque control and pitch control strategy in VSCF wind turbine above rated wind speed

Above rated wind speed, the wind turbine speed and output power are maintained near the rated values through the coordinative control of torque and pitch angle. Due to the non-linear behavior of the wind turbine, the traditional PID control is not effective in the pitch control. And accurate mathematical model of wind turbine is very difficult to get. In order to solve the problem, the fuzzy adaptive tuning PID control algorithm is proposed in the paper. About torque control strategy, constant torque control mode and constant power control mode are simulated respectively. Based on the analysis and comparison of the advantages and disadvantages of both modes, a mix control mode is proposed in order to give consideration to both torque and power. Simulation was carried out with the proposed torque control and pitch control strategy in MATLAB and GH Bladed software. The results proved that output power is optimized and the response of the wind turbine is good.