A frequency separation control strategy for hybrid renewable energy management with electric vehicle in a Tunisian building

This study presents an innovative energy management system based on a frequency separation strategy for a standalone hybrid renewable energy system. The system, which integrates photovoltaic, wind, battery, and fuel cell sources, is designed to meet the residential load demands of a building in Tunis el Manar, Tunisia. A key feature is the incorporation of Vehicle-to-Home technology through a bidirectional electric vehicle charger, which enhances renewable energy utilization and reduces infrastructure costs. The primary objectives of the proposed energy management system are to minimize operational costs by optimizing power flow, reducing hydrogen consumption, and critically, extending the fuel cell's operational lifetime. The control strategy was rigorously evaluated through MATLAB/Simulink simulations and validated using an enhanced lab-scale prototype, tested under various operating scenarios and real-world load profiles. Results demonstrate that the system robustly manages renewable generation variability and load demand, maintaining DC bus stability under fluctuating climatic conditions. The strategy significantly reduces system sensitivity to load changes, with the battery effectively mitigating high-frequency power fluctuations to ensure fuel cell reliability. This approach yielded two key economic outcomes: it increased the fuel cell's maximum operating hours from 5000 to 50,000, and facilitated a reduction in the hydrogen cost to below 7 €/kg (0.21 €/kWh). These findings confirm the strategy's effectiveness in advancing the goal of net-zero-energy buildings in a economically viable manner.