Coordinated Control of the Bus Tie Switches and Power Supply Converters for Fault Protection in DC Microgrids

For dc microgrids, coordinated operation of electronic power converters and mechanical contactors can rapidly isolate short circuit faults while maintaining continuity of power to loads. The entire process—rapidly limiting current, deenergizing the bus, reconfiguring the bus via segmentizers or bus ties, and reenergizing the network—can be accomplished in milliseconds, during which time diode-isolated load-side hold-up capacitors continue supplying power to critical loads. For a wide range of systems, reconfiguration can be accomplished in 8–10 ms, which is fast enough to comply with requirements of CBEMA and IEEE standards on power quality. Reconfiguration time depends on the power system dimensions, the number of sources connected to the system, the system nominal voltage, and the performance of segmentizers.