Horizontal Axis Wind Turbine Pitch Actuation Fault and Reaching Law Based Sliding Mode Controller Performance Analysis

Wind turbine performance largely depends on the implementation of suitable controllers in the turbine side and generator side. The generator side controller is responsible to maintain generated power quality i. e. frequency of the generated power. On the other hand, the turbine side controller regulates rated power at above-rated wind speed by pitch control and maximum power tracking in below-rated wind speed through turbine speed/torque control, maintaining optimum operating condition. The asymmetric blade pitch control gives rise to a high workload on a pitch actuation system. The increased workload on the pitch actuation system, impure hydraulic oil, improper selection of actuator seal may cause failure in the electrohydraulic pitch actuation system. In this study, a detailed analysis of the impact of actuator fault on control performance has been undertaken for a horizontal axis wind turbine pitch actuation system, controlled by sliding mode controllers. The passive fault tolerance control has been implemented by designing two reaching law-based sliding mode controllers, named as CPRRL-SMC and EERL-SMC. The performances and relative robustness of both controllers have been analyzed in detail both for healthy as well as faulty situations.