Control of a horizontal axis wind turbine using H infinity control

An H infinity controller based on a linear model that reduces fatigue damage of a wind turbine is designed. It is important that the system be robust, especially at 1 omega _r and 3 omega _r, which are the most prominent rotational disturbances which act on the system. In order to avoid actuator saturation, a detuned controller is designed. When the windspeed rises above the rated speed, the controller must unwind and attain the correct state before normal control can continue. This is achieved by splitting the detuned controller into two parts. Simulation results are presented, showing that the detuned controller overcomes the problems of actuator saturation and instability, but that the overshoots in the power and torque plots are still too large.