Analysis of fault characteristics in DC microgrids for various converter topologies

Protection is an important factor affecting the viability of dc microgrids in future. Traditional ac protection methods are not directly applicable to the dc microgrids due to more extensive use of power electronic converters as compared to the ac systems. Behaviour of different converters during fault is not identical and depends on the converter topologies. Some converter topologies are capable of controlling its output current and hence reduce the risk of system failure. While other topologies are unable to limit the current and require external devices such as fuse, breakers to protect itself. Therefore, a detailed study of various power electronics converters response for different types of faults is desirable. In this paper, analysis of direct short circuit and monopole to ground fault are analysed for different converters. The fault current transient is characterised in terms of peak value and time to reach the peak current. The results are verified through simulations for different converter topologies using Real Time Digital Simulation (RTDS).