This paper presents a power management strategy to control a DC microgrid considering the operation in the grid connected mode. The analyzed system is composed of the utility grid interfaced with a voltage source converter, an energy storage system (ESS), a distributed generator and the customer loads. The proposed power management is considered as a master-slave technique, in which the VSC operates as a master grid-forming converter, while the ESS is a slave grid- supporting unity and the distributed generator works as a grid-feeding unity tracking the maximum power point. This management strategy is presented in details and its impact over the DC link voltage, the power flow and the ESS state of charge is analyzed. MATLAB/Simulink simulations are performed to obtain the results. The obtained results show that the proposed strategy is reliable and leads to better controllability over the power flow in the DC microgrid when compared with the hierarchical control.
Keywords DC microgrid, Power management, Energy storage system, Master-slave control, Grid connected mode.