The Improved Coordinated Control Method of Islanding and Grid-Connected Operations for DC Microgrids

Abstract

The DC microgrid plays an essential role in realizing smart power supply systems for the DC loads. It combines various distributed generations and transmits the power to the loads or the utility grid through the DC bus. It attaches great importance to energy management because of the load and photovoltaic power fluctuations. This paper proposes an improved coordinated control based on the characteristics of various distributed generations and utility grids. The proposed method can realize the stabilization of bus voltage when the system switches between multiple operating modes in grid-connected and island mode due to the change of energy. Compared with the present ways, the proposed method provides a further optimization on the design of charging for energy storage units in the grid-connected mode and the current sharing with the backup storage units in the islanded mode which is conducted by SoC balancing droop control. Finally, the DC microgrid simulation platform is built to verify the correctness and feasibility of the proposed method.