Analysis of LVDC Microgrid Protection Requirements and Application of Hybrid Circuit Breaker

In the low voltage (LV) distribution network, DC microgrid has been widely considered for its convenient and efficient absorption of new energy. With the multi-terminal access of photovoltaic, energy storage and other distributed energy sources, the fault characteristics of DC microgrid become more complex, which also puts forward higher requirements for protection.Based on the fault characteristics analysis of single-terminal DC microgrid, this paper considers the key protection problems of multi-terminal DC microgrid. The simulation model is built based on MATLAB/Simulink, and the direction, magnitude and rising rate of fault current are analyzed. The results show that the protection equipment of DC microgrid needs to meet the requirements of bidirectional power flow breaking, rapidness and selective protection, to ensure the safe and reliable operation. Hybrid circuit breaker (HCB) is considered to be the equipment that best matches the protection requirements of DC microgrid. HCB topology is designed, prototype is built, and the feasibility is verified by experiment. Finally, the possible optimization strategies are proposed. This paper provides valuable ideas for the study of specific problem and the improvement of fault breaking strategy in the field of DC microgrid protection.