Adaptive Fault Interruption Coordination in DC Microgrids Based on Current Rise Rate

DC microgrids are increasingly recognized as a promising solution for enabling an efficient and reliable energy transition. However, their widespread deployment remains constrained by the inherent complexity of DC microgrid protection. The short length and low inductance of DC distribution lines, combined with large DC-link capacitors, result in extremely steep short-circuit current transients with rates of rise reaching several hundreds of amperes per microsecond, leaving a very limited time window for fault detection, interruption, and selective operation. This paper proposes a novel protection coordination strategy for radial DC microgrids that employs the rate of rise of fault current as the primary coordination parameter. In contrast to most existing approaches, which rely mainly on the absolute magnitude of fault current and face inherent limitations in DC systems, the proposed method investigates the feasibility of using the fault current slope as the key coordination metric and establishes systematic criteria for determining appropriate threshold settings for circuit breakers at different locations within the microgrid. The proposed strategy is validated through comprehensive simulation studies under various grid configurations and load conditions, and the results demonstrate effective coordination of multiple circuit breakers using the proposed threshold-setting framework, ensuring selectivity, and fast fault isolation.