I. INTRODUCTION
Wind power is a kind of renewable energy and plays an important role in the future energy supply. Without question, the safe o peration of control system which is the center of wind turbine is essential to ensure the running of the unit. However, wind turbine usually works under the bad environment. The gearbox and bearing failure [1]–[3] and various sensor faults often occur, such as sensor bias fault, sensor constant gains and so on. When fault occurs it will seriously affect the engineering quality and cause great economic losses. So the fault diagnosis of wind turbine control system is becoming more of a concern.