Integrated Energy Management and Impedance-Based Fault Protection for Sustainable Renewable DC Microgrids

This paper presents an integrated energy management and protection framework for sustainable renewable DC microgrids. The proposed system combines energy management, fault detection, selective isolation, and impedance-based fault-distance estimation using local voltage and current measurements. The studied 400 V DC microgrid integrates photovoltaic and wind generation with battery energy storage and AC/DC loads. Intelligent electronic devices (IEDs) continuously monitor line currents and coordinate circuit breakers to rapidly isolate faulted sections, while the energy management system regulates the DC-bus voltage and maintains power balance under normal and fault conditions. The framework is evaluated in MATLAB/Simulink under line-to-line and line-to-ground faults at different locations and fault resistances. The results show fault isolation within 0.01 ms, with maximum localization errors of 0.78% for L–L faults and 1.35% for L–G faults. The broader sensitivity analysis shows a maximum error of 2.74% at RF = 2Ω, while the DC-bus voltage is restored to approximately 400 V following fault isolation. By coordinating renewable generation, storage, and protection within a unified architecture, the proposed approach improves reliability, operational continuity, and the efficient use of renewable energy resources, supporting the resilient and sustainable operation of DC microgrids.