DC microgrids are increasingly becoming a popular choice for EV charging infrastructure, as they allow the integration of EV chargers, PV panels, BESS, etc. with the DC grid without an intermediate DC-to-AC conversion. SSCBs can provide reliable protection from short-circuit events on the DC microgrids as they can respond rapidly and interrupt fast-rising DC fault currents. One of the key aspects of protection reliability is limiting the zone of power interruption to a bare minimum, and this requires that multiple SSCBs in the DC grid coordinate their operation with each other as they interrupt the fault current. At low fault-di/dt levels, this can be achieved by time-offsetting the trip curves or by using communication between SSCBs. However, at high fault-di/dt levels, the propagation delays associated with these techniques limit their effectiveness. This digest investigates the performance of a hardware-based protection scheme in improving protection coordination between SSCBs at high fault-di/dt levels. This scheme is then implemented in high-current SSCBs that utilize reverse blocking IGCTs for fault interruption to explore their fault-di/dt limits for successful coordination.
