Research on Multi-mode Stability Control Strategy of DC Microgrid

With the higher permeability of renewable energy generation in modern electric power system and more complex load demand, DC microgrid becomes a new grid structure composed of distributed power supply, energy storage device and control system. In order to improve stability of electricity supply, its control strategy is very important. Firstly, the composition structure of DC microgrid is introduced, and the basic functions and models of each unit are established. Secondly, in terms of the equivalent circuit of DC bus, the control objective of DC microgrid system is analyzed and the basis of coordinated control strategy is determined. Then, taking the lowest and highest critical voltages of grid-side converter and energy-storage converter as mode switching conditions, four operating modes of DC microgrid are constructed, so that the DC microgrid can maintain stable operation in each state. Meanwhile, the topology structure and control method of each converter are studied. Finally, the corresponding simulation model is built in MATLAB/Simulink, and the proposed control strategy is verified.