Energy management and control strategy for DC micro-grid in data center

DC micro-grid, as a self-management grid form of integrating distributed energy systems with utility power systems, will efficiently realize the value and benefit of the distributed energy resources. In this paper,the DC micro-grid mainly consists of five parts: a PV source, a DC/DC converter, a battery energy storage unit, a bi-directional DC/DC, and a bi-directional DC/AC which is connected to the main grid. This DC micro-grid has different control strategies according to different operating modes (grid connected, islanded). Then its control mode is designed and investigated by MATLAB/Simulink models. The simulation results verify the validity of the mathematical model and the feasibility of the proposed control strategies. In the grid connected mode, the transfer energy can flow in bi-directional modes, and DC bus voltage level can be stabilized by DC/AC converter. In the islanded mode, the battery converter serves as a voltage source to ensure a stable DC voltage. At last, DC micro-grid experimental system is used to examine its switching functions among different control modes. The experimental results demonstrate that high quality power can be supplied.