Study of the Hierarchical Control System for DC Micro-grid

In order to better realize the plug and play function of various distributed energy sources (photovoltaic, storage batteries, etc.) in the DC micro-grid, improve energy conversion efficiency and improve DC side bus voltage performance. The layered control strategy introduced contains two layers: the new energy in the inner layer of the micro-grid is maximized by the maximum power tracking control, and the energy storage unit uses the voltage leveling control to ensure the stability of the DC side bus voltage; The bidirectional vector decoupling control includes voltage and current double closed loop control, and uses d-q coordinate axis transformation to control DC voltage and power factor to solve the problem of bidirectional flow of power during grid connection. This paper gives a detailed theoretical analysis and design method for each layer control. Simulation results demonstrate the feasibility and effectiveness of the proposed method.