Feedback-feedforward individual pitch control design for wind turbines with uncertain measurements

As the diameters of wind turbine rotors increase, the loads across the rotors are becoming more uneven due to inhomogeneous wind fields. Therefore, more advanced passive or active load reduction techniques are introduced to mitigate these uneven loads. Furthermore, measuring the disturbance can help to improve the control performance. This paper first examines how robust stability and performance are affected by uncertain sensor measurements when an integrator-based feedback is extended with an inversion-based feedforward individual pitch controller with similar bandwidth. A fixed-structured H_∞feedback-feedforward controller is proposed. The proposed feedback-feedforward controller ensures robust stability and performance and achieves better load reduction than a classical integrator-based feedback controller combined with inversion-based feedforward controller.