Modeling and Simulation of Protection Logic for In-Feeder Fault Detection in a Microgrid System

Abstract

The issue of ensuring selective and reliable earth faults in modern microgrids still persists due to sympathetic zero sequence currents and multi-source coupling complexities. In this paper, the customized Earth Fault Protection (EFP) logic has been formulated and tested to successfully discriminate between true in-feeder Earth faults and other non-fault sympathetic currents within the AC microgrid environment modeled in MATLAB/Simulink. The customized logic utilizes the dual-threshold strategy with residual current ( I ₀) and the minimum phase current ( I min ), further bolstered by time-blocking action to prevent unwarranted operations. The simulation results indicate that the customized protection logic provides complete immunity to false operations during sympathetic I ₀ currents. Yet, it also manifests sensitivity to low-intensity internal faults if the stationary I min threshold is unexceeded. The customized solution compares favorably with the state-of-the-art in terms of simplicity, understandability, and direct realizability without requiring heavy computations through artificial intelligence frameworks such as ANFIS topology-independent models and AI-powered microgrid fault detection techniques.