A New Adaptive Virtual Impedance based Fault Current Limiter for Converters

Fault current limiter (FCL) can be used to prevent converters from being damaged and miscoordination of the protective relays. FCL must be designed to have high efficiency, fast response, and low implementation cost. Accordingly, this paper proposes an adaptive virtual impedance (VI) based FCL for a four-wire system. In normal condition the exerted additional VI is zero; however, once the fault occurs the VI of the faulty phase will be increased until it limits the output current of the converter to a specific value. In order to have a fast-acting FCL, an adaptive moving average filter phase locked loop has been proposed to measure the output current with the lowest possible time delay. Since the proposed FCL does not use any external device, the implementing cost is almost zero. In addition, it has a very high time response and only limits the current of the distribution generator (DG) faulted phase. This paper also provides real-time simulation results by simulation and experimental results to compare the proposed method with the non-adaptive virtual-impedance-based FCL to validate its effectiveness.