A Centralized Power Flow Control Scheme of EV-Connected DC Microgrid to Satisfy Multi-Objective Problems under Several Constraints

Integrating electric vehicles (EVs) into a microgrid improves the efficiency, flexibility, and robustness of microgrids. Unfortunately, the uncertainties of EVs, in terms of their connection/disconnection times and their initial SOC values, make integrating EVs into microgrids a more challenging issue. Contrary to the standard energy management system (EMS), integrating EVs into microgrids raises several multi-objective problems that need to be solved. In this study, a centralized power flow control scheme for an EV-connected DC microgrid (DCMG) is proposed to satisfy these multi-objective problems under several constraints. Two prime objective functions of the DCMG are presented to demonstrate the benefits to both the DCMG system and EV owners. Then, a reliable and optimized DCMG system is constructed to satisfy the selected prime objective function. The operating modes of each agent in the DCMG are defined based on information regarding the EV connection/disconnection status, the initial EV SOC values, the generation power of the wind power agent, the battery SOC levels, and the grid availability. The effectiveness and robustness of the proposed scheme have been validated by in-depth simulations and experimental tests under the uncertainties of DG power, grid availability, electricity price conditions, and EV connections. In addition, the proposed scheme reliably regulates the DC-link voltage without severe transience, even if these uncertainties cause the task of controlling the DC-link voltage to be transferred from one agent to another.