Fault Analysis and Relay Assessment on a Substation System with High Penetration of PV Generation

With the dramatic transition in distribution power systems from centralized generation to distributed generation (DG), the system fault responses, especially fault current profiles, are going to experience some major changes. These are likely to cause issues in the traditional overcurrent relay such as overlapping coordination and sensitivity deterioration. This paper, based on a Dominion Energy virtual substation system with a high solar energy penetration level, studies both the photovoltaic (PV) inverter fault responses and the distribution system fault-current profile under various fault scenarios. These include analyzing three-phase and single-phase faults under different fault severities and at different locations within the substation. The corresponding performance of an overcurrent protective relay in the substation system was also assessed. A hardware-in-the-loop (HIL) testbed was implemented for validation purposes, with an actual SEL-451 interfacing the real-time simulation in the RTDS platform. The HIL simulation results verify the effectiveness of the presented fault analysis methodology.