The Study of Locating Ground Faults in DC Microgrid Using Wavelet Transform

Abstract

As the proliferations of distributed generation and power electronic equipment in power systems, direct current (DC) microgrid emerged and attracted more and more researchers’ attentions. Protection of DC microgrid is a big challenge and to build a well-function protection system, locating the faults accurately is a critical issue. It is easy to find the location of short circuit faults in DC microgrid. However, it is difficult to locate ground faults in DC microgrid because of the spray capacitors and the large amount of distributed resources. In this thesis, Wavelet Transform is applied to decompose the common mode currents that is collected at different sensor points in a DC microgrid and capture the characterization of every single ground fault. And based on these characterizations, a single ground fault location algorithm is proposed. MATLAB/Simulink and PLECS are used to assist in the process. Simulink is used to build the three phase source feeding the DC microgrid and PLECS is used to build the model of DC microgrid and measure the common mode current at different sensor points when a single ground fault is applied.