Dynamic Simulation of Vanadium Redox Flow Batteries for Remote Isolated Microgrids

This study investigates the dynamic performance of a vanadium redox flow battery (VRFB) integrated into a photovoltaic (PV)‐based remote isolated microgrid (IMG), with emphasis on the influence of electrolyte flow rate on electrochemical behavior, energy delivery, and operational stability. A MATLAB/Simulink model was developed to represent the coupled PV–converter–VRFB–inverter system under a realistic load profile derived from an isolated community in Maranhão, Brazil. The analysis considered charge/discharge voltage response, state‐of‐charge (SoC) evolution, charge capacity, energy efficiency, coulombic efficiency, and usable energy under different flow‐rate conditions. The results show that electrolyte flow rate strongly affects VRFB performance by modifying mass transport and polarization losses. Increasing the flow rate from 67 to 132 mL·min −1 raised the charge capacity from 438.9 to 563.5 Ah, corresponding to a 28.4% improvement, while the highest energy efficiency (75.58%) and coulombic efficiency (81.18%) were obtained at 132 mL·min −1 . A slightly higher usable energy was achieved at 181 mL·min −1 (96.53 kWh), whereas the maximum average power output occurred at 321 mL·min −1 (18.99 kW). These results indicate that the most favorable operating window lies between 132 and 181 mL·min −1 , where electrochemical utilization, voltage stability, and energy delivery are jointly optimized. The optimized VRFB configuration was able to supply the nighttime demand of the studied microgrid (95.6 kWh·day −1 ), demonstrating its suitability for long‐duration storage in off‐grid applications. Overall, the findings confirm that flow‐rate optimization is a key design variable for improving VRFB performance and enhancing the resilience of renewable‐based IMGs.