Impact of Grounding Conditions on Power Electronic Interfaces in a DC Microgrid

This paper analyses DC and AC fault transients in DC microgrids using voltage source converters as power electronic interfaces. DC microgrid structure and grounding resistance have considerable impact on overcurrent and overvoltage transients experienced by power electronic converters. Therefore, grounding resistance monitoring in real time and simulation of grounding structure impacts on overvoltage and overcurrent transients are crucial. For this purpose, new models for two-level voltage source converters are proposed under different AC and DC fault conditions. The considered faults include single phase to ground, double lines to ground, positive pole to ground, and negative pole to ground faults. Using the derived models, the impact of different grounding methods on the transients experienced by the switches is examined in detail.