Impact of System Grounding on Distance Relay Operating

This paper investigates the impact of the system grounding on the accurate operation of the distance relay. How the neutral is grounded determines the behavior of a power system during a single-phase to ground fault. Thus, it decides the circulation or not of zero-sequence current. This can affect the fault impedance of transmission line and creates under-reaching issues in distance relay. To tackle this challenging problem, a new approach based on the management of the system grounding is proposed in this paper. A comparison study that highlights the merits and demerits of each grounding mode are given to test the impact of the grounding system on the fault current. Simulation results are performed in a test system under MATLAB environment.