Optimal storage utilization and reliability assessment in AC/DC microgrids with environmentally driven renewable integration

This paper presents a day-ahead optimal power dispatch framework for grid-connected AC/DC microgrids integrating Renewable Energy Sources (RESs) and Battery Energy Storage Systems (BESSs), aiming at power supply improvement in off-grid mode. The optimization minimizes energy imported from the main grid while maximizing the state of charge (SoC) of BESSs. Renewable power outputs were modeled for various scenarios related to external conditions using time series analysis of historical environmental data, such as wind speed, solar irradiation, and temperature. The energy management strategies were evaluated under these scenarios, including transitions to islanded mode triggered by grid faults. In grid-connected mode, a new adaptive SoC-based charging/discharging strategy is incorporated into the objective function. This strategy not only minimizes the total operation cost but also ensures that storage systems maintain sufficient energy to supply critical loads during islanded mode while reducing the frequency of switching between charging and discharging operation modes. In islanded operation, two reliability indices were introduced to measure resilience under different scenarios. In both on-grid and off-grid operation modes, a SoC balancing strategy is considered to prolong the lifespan of the BESSs. The application of the proposed model to three case studies under various energy scenarios is programmed and simulated in Python. The findings indicate that: (1) the SoC of storage systems may change depending on the season and energy scenario; (2) fast SoC balancing convergence is possible; and (3) the worst energy scenarios can sometimes lead to greater resilience, although they may also result in lower average reliability overall. © 2026 The Authors.