Distributed Energy Resources Large-scale Integration Impacts on the Distribution System Protection

This presentation examines the impact of high DER penetration, particularly PV systems, on EPDS protection reliability. Instead of concentrating DERs in specific nodes, they are distributed along an unbalanced feeder with single-phase and three-phase PV systems. Various fault types, including impedance faults, were analyzed using the IEEE 34-node test feeder in EMTP-RV. Three scenarios were considered: (i) without DERs, (ii) 50% DER penetration with protection set by rated load, and (iii) 50% DER penetration with protection set by conductor capacity. Results showed reduced feeder relay currents for three-phase and phase-to-phase faults and significant decreases for phase-to-ground faults with impedance, leading to relay blindness and delayed protection operation. These insights support utilities in adapting EPDS protection systems for DER integration.