Active FTC for Hydraulic Pitch System for an Off-shore Wind Turbine

This paper describes the development and testing of the implementation of a linear parameter varying (LPV) fault tolerant control (FTC) approach to hydraulic pitch actuation for an off-shore wind turbine (OWT) system with independent pitch actuators. The study involves two separate actuator fault scenarios. In the first scenario the pitch actuator position sensor signal is considered to be stuck at a fixed value. In this case, a fault hiding approach is used to compensate for this fault in the control system, as a form of sensor FTC scheme with fault estimation. The second fault scenario is caused either by a drop in pressure in the hydraulic supply system or the high air content in the oil. In this case, the fault-free pitch actuator systems are both utilized to synchronize all three pitch systems in order to prevent further damage caused by unbalanced structural loads.