Discrete-time LQG control with disturbance rejection for variable speed wind turbines

In this paper a discrete-time LQG controller is proposed for horizontal wind turbines, which makes possible to eliminate the disturbance influence on the system output. The control objective consists of maintaining the output power constant despite the wind variation, reducing, in the meantime, the fatigue that leads to damage of the turbine components. The discrete LQG controller has the advantage that can be easily implemented on a physical controller in order to be used on a real wind turbine. The wind turbine behavior is described by a nonlinear model based on the general equation of motion in a mechanical system and other equations specific to the system. The model is then linearized around a particular operating point in order to obtain a wind turbine system representation suitable for controller design. The performances of the system controlled with a discreet LQG controller are illustrated and analyzed using a simulation environment.