Enhancing Breakerless Protection in DC Microgrids: Power Outage Analysis and Grid Segmentation

Due to the characteristics of dc fault currents, particularly the missing zero crossing, protection in dc microgrids is a major challenge. In contrast to widely discussed breaker-based concepts, breakerless protection controls the fault current using power electronic converters, and interrupts based on no load contactors to isolate the fault location. As these no load contactors are only capable of interrupting very low currents, the grid must be de-energized, which results in an prolonged power outage, and thus counteracts one of the primary objectives of a grid operator: high system availability. Therefore, this paper investigates the fault current in breakerless protection-based systems with focus on the infuencing factors on the additional outage duration. Moreover, the paper suggests grid segmentation based on dc-dc converters as segmenting components to ensure protection selectivity, and elaborates on suitable converter topologies.