A hierarchical grounding protection strategy for integrated power systems using a composite criterion

Unipolar grounding faults in shipboard medium-voltage DC (MVDC) systems can easily cause voltage imbalance, posing a threat to the stability of power supply. To address this issue, this paper proposes a composite criterion-based protection method that utilizes both leakage voltage and leakage current. The method comprehensively considers factors such as the degree of voltage unbalance, bus voltage drop, leakage current direction, and grounding resistor current to determine the fault type and location. Simulation results verify that the proposed method can effectively identify different types of grounding faults and demonstrates strong robustness against high transition resistance.