Development of an IGBT-Diode based Fault Current Limiter for Fault Ride-Through Enhancement in Microgrid Application

This paper deals with a developed insulated gate bipolar transistor (IGBT) and diode based fault current limiter (FCL) for simple microgrid application. The developed FCL utilizes a three-phase circuit arrangement that has fault current limiting ability with an uncomplicated control strategy that simply samples the voltage at the point of common coupling (PCC) for the FCL control using Clarke's Transformation, low pass filtering and pulse generating circuit. The IGBT-Diode based FCL regulates the magnitude of the fault current and enhances the PCC voltage under transient faults to ensure continuous supply of active and reactive power to the local load of the microgrid irrespective of the transient condition of the main grid. The power electronic switching arrangement employed interfaces the grid using an isolating transformer whose primary is connected in series with the feeder line and the secondary is shorted by an optimally sized AC reactor. The IGBT-Diode switching operations for the pre-fault, fault and post-fault conditions are triggered by the control proposed which detects fault occurrence in less than a period. The analytical investigation of the IGBT-Diode switched FCL is presented in details and the results of simulation lay credence to effectiveness of the developed FCL in improving Fault Ride-Through (FRT).