A disturbance accommodating Linear Quadratic Regulator (LQR) method was applied in pitch control system to achieve good performance. The disturbance can be estimate by designing state estimator, and a feedback was added into the input to eliminate disturbance effect. The feed back matrix was calculated in accordance to LQR theory. A wind turbine dynamic modal was set up, and simulation of the control system was preformed based on Matlab7.1/simulink. The simulation results show that the controller ensure pitch control actuator little fatigue, and has smaller overshoot. The proposed method is has better performance and easy to realize.

With an increasing amount of wind energy installed, the behavior of wind power system during grid disturbances becomes more important, grid operators require that wind turbines stay connected to the grid during voltage dips. A control method can be used to keep direct-drive wind power system with back-to-back converters using permanent magnet generator connected to the grid during voltage sags. When the voltage sags happen, the grid-side converter of direct-drive wind power system operating at STATCOM mode, the reactive current is determined by the depth of voltage sag, then the reactive power can be rapidly provided to support the grid and help direct-drive wind power system low-voltage ride-through. All this was verified by simulation and experiment. This is illustrated that for direct-drive wind power system, the capability of low voltage ride through can be effectively improved by operating at STATCOM mode during grid voltage sags. Index Terms: Wind power system, Permanent magnet synchronous generator(PMSG), Voltage sag, Low-voltage ride-through(LVRT), Full power converter, STATCOM