DC Fault Detection Scheme for Multi-terminal Hybrid AC/DC Distribution Network Based on Current-limiting Inductor Voltage

Abstract

Rapid and accurate detection of DC faults is a key technologies for development of multi-terminal hybrid AC/DC distribution networks. DC fault currents rise rapidly after DC fault and traditional AC fault detection methods are no longer suitable for DC faults. A DC fault detection scheme based on voltage change rate of DC current-limiting inductor for multi-terminal hybrid AC/DC distribution network is proposed in this paper. Firstly, the characteristics of DC faults are analyzed thoroughly. Based on this, a method detecting DC faults using single-end current-limiting inductor voltage change rate is proposed. Secondly, a comprehensive fault detection scheme identifying faulty line, fault type and faulty pole is designed, and corresponding threshold selection method is studied in detail. Finally, the proposed fault detection scheme is verified with MATLAB simulations. Simulation results show that the proposed scheme is accurate and fast enough for different fault resistances and different fault distances, not affected by power reversal of the converters.