Low-Voltage DC Ring-Bus Microgrid Protection with Rolling Mean Technique

On the event of a fault contingency in a low-voltage DC ring bus microgrid, de-energization of the microgrid can be eluded if the protection scheme is eminently responsive and selective so as to rapidly isolate the faulty segment. The paper proposes a complete protection scheme comprising of two subroutines which are fault segment identification (FSI) and fault distance location (FDL). The microgrid is not de-energized as local identification and isolation of the fault segment is executed with Rolling Mean Technique (RMT) on system bus voltages. Once FSI is executed, probe power unit (PPU) is employed to implement FDL without linearization of the fault current response. The paper proposes a scheme which is immune to fault resistance value, fluctuations in the voltage and the variation in the system state. MATLAB/SIMULINK is employed to validate the scheme proposed in the paper for different values of fault resistances and fault locations with all DC faults considered.