Unknown Input Observer Based Scheme for Detecting Faults in a Wind Turbine Converter

In order to improve reliability of wind turbines, it is important to detect faults in the turbine as fast as possible to handle them in an optimal way. An important component in modern wind turbines is the converter, which for a wind turbine control point-of-view normally provides the torque acting on the wind turbine generator, as well as measurement of this torque. In this paper an unknown input observer is presented to estimate these faults in the converter and isolate them either to be an actuator fault or a sensor fault. The unknown input observer is used since the speed of wind acting on the wind turbine is assumed unknown, since measurement of it is influenced by the turbulence around the rotor plane. A detection scheme is formed based on these fault estimates. A detail simulation model is used to simulate a wind turbine in which both types of faults are present during the simulation. The detection scheme detects and isolates both faults with in 2 samples of its beginning.