Diagnosis of the open-circuit fault in three-parallel voltage-source converver for a high-power wind turbine

A fault detection method for the switch devices of three-parallel power converters in a wind turbine system is presented. The proposed method utilizes the measured 3-phase currents which were already used for controlling the converters. Additional current and voltage sensors are thus not necessary. Consequently, this particular feature potentially cuts costs to apply the detection algorithm. The 3-phase currents are transformed to a stationary reference frame. This reference frame possesses specific patterns in accordance to the conditions of the switch devices in the converter. Open faulty switches can be detected by analyzing the obtained pattern. The reliability of the proposed fault detection method was proven by simulation results.