Applicability Analysis of Directional Overcurrent Relay without Voltage Reference in Microgrids

This paper presents an approach for identifying the direction of faults with only current measurements in distribution networks in the presence of distributed generation. The proposed protection system guarantees protection selectivity in distribution systems considering the possibility of fault currents in both directions of the distribution lines. Firstly, the methodology of directional protection is developed and discussed. Subsequently the performance and efficiency of the directional protection tool is evaluated through its application for a test system based on a real system. Single phase and three phase faults have been simulated and the results demonstrate that the use of the directional protection system with only current measurement in distribution networks is feasible and a promising approach for selectivity and coordination of relays.