Dynamic Adaptive Protection for Distribution Systems in Grid-Connected and Islanded Modes

Reliable protection of distribution systems is becoming increasingly challenging with growing distributed energy resources (DERs) and microgrids. Existing adaptive overcurrent relaying (AOCR) schemes are vulnerable to DER ride-through and generally focus on only grid or islanded modes. This paper presents a dynamic AOCR scheme independent of external controllers to estimate relay pickup that ensures significantly less communication overhead. Existing and emerging challenges for the state-of-the-art are discussed and resolved using the proposed scheme. The reliability is tested using transient system models in Simulink for all combinations of state and fault types/impedances in a 15-bus distribution system.