Real time fuzzy energy management of hybrid storage systems in DC microgrids with dynamic voltage restorer assisted power quality enhancement

Abstract

This paper presents a real-time fuzzy logic-based energy management system (EMS) for a hybrid DC microgrid supplying a constant DC load and an AC sensitive load protected by a dynamic voltage restorer (DVR). The system integrates a 25-kW photovoltaic (PV) array, a 10-kW fuel cell (FC), a 15-kW battery energy storage system, and a 396 V supercapacitor bank. The EMS calculates the net power balance (ΔP = PPV - Pload), compares it with the states-of-charge (SoC) of the battery and supercapacitor, and dynamically allocates power references to each source. Fuzzy rules prioritize renewable generation, exploit the supercapacitor for fast transient compensation, and schedule the battery and fuel cell for medium- and long-term power balancing. The DVR acts as a series active power filter, injecting real power during sags and absorbing excess energy during swells, while the EMS maintains DC bus stability under fault conditions. Simulation results demonstrate enhanced DC bus voltage regulation, reduced battery cycling, efficient hydrogen utilization, and rapid recovery from voltage disturbances. The proposed strategy improves power quality and ensures continuous operation of sensitive loads, making it suitable for smart grid and renewable-based microgrid applications.