In this paper, a new protection scheme, based on rate-of-rise of fault current with adaptive current threshold, is proposed to provide fast and accurate fault detection in DC microgrid. It utilizes the peculiarity involved with the DC faults i.e. the DC fault current increases very fast to a high value. Therefore, under the scheme, each relay detects a fault if the time interval, during which the fault current rises from minimum to maximum value, is below the predefined threshold value. The efficacy of the proposed scheme is validated on a 380V ring-type DC microgrid simulated considering different fault conditions with various fault resistance values at different fault locations. The simulation results obtained under distinct operating conditions indicate high selectivity and high speed of operation of the proposed scheme for fault detection and isolation (less than 1ms). The proposed scheme is compared with the existing protection techniques in the literature which exhibits comparatively better effectiveness and reliability of the proposed technique.
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