A Novel Secondary Optimal Control for Multiple Battery Energy Storages in a DC Microgrid

The distributed controller consisting of a voltage controller and a power controller is commonly employed on the secondary control layer in the DC microgrid. In this paper, a novel optimal control based on the PI consensus algorithm is proposed for multiple battery energy storages (BESs) in an islanded DC microgrid. Compared with the conventional distributed voltage controller, the proposed scheme improves the system robustness to time delays. The steady-state analysis is conducted to verify that the proposed scheme can take effect in case of time delays. The impact of the secondary controller on the dynamics of the system under time delays is investigated by the eigenvalue analysis. Simulation results confirm that favorable power sharing and DC voltage regulation as well as robustness to time delays achieved by optimal control in an islanded microgrid with multiple BESs and constant power load (CPL).