Nonlinear control for variable-speed wind turbines with permanent magnet generators

This paper proposed a nonlinear control algorithm for a variable-speed wind turbine without wind speed measurement. The measured permanent magnet generator output current, terminal voltage and shaft speed are used to estimate the electromagnetic torque of the permanent magnet generator by using Kalman filter. Then the wind speed is estimated by Newton-Raphson method after obtaining the estimated power of the wind turbine. The wind turbine is controlled through the adjustment of the electromagnetic torque of the permanent magnet generator for maximum power point tracking below the rated speed. The nonlinear controller for variable-speed wind turbine with the wind speed estimator has good dynamic performance and high power capture efficiency.