Variable structure strategy to avoid torque control saturation of a wind turbine in the presence of faults

Every physical actuator is subject to saturation. It has been well recognized that, when the actuator saturates, the performance of the closed-loop system (designed without considering actuator saturation) may seriously deteriorate. In extreme cases, the system stability may even be lost. This paper proposes an avoid saturation strategy for the torque controller of a wind turbine benchmark model. The simulation results show that the proposed strategy has a clear added value with respect to the baseline controller (wellaccepted industrial controller) in the presence of faults. Another advantage of the contributed method is that conservative bounds for the actuator torque can be fixed in order to extend the service life of the wind turbine.