Short-Circuit Fault Analysis of Energy Storage System Converter with Different Control in DC Microgrid

Energy storage system plays an important role to operate the DC microgrid stably and improve power quality. When it is connected to the DC system through the bidirectional DC/DC converter, the energy storage system is of great significance to study fault characteristics of the energy storage converter for the rational design of relay protection. This paper investigates system response characteristics of energy storage systems in different fault stages under constant voltage control and droop control when short-circuit faults occur in DC microgrid, and compares effects of the two control methods on short-circuit fault characteristics. The results show that different control modes have a certain restraining effect on the fault behavior of DC microgrid, but the inrush current is too large at instantaneous failure. Therefore, the latching control should be carried out in time; meanwhile, a reliable and effective protection device should be added. In addition, the research shows that the capacitance and line parameters at the dc grid side also have influences on fault response characteristics of the energy storage converter. Finally, the simulation model of DC microgrid connected to the energy storage system is built on PSCAD / EMTDC to verify correctness of the theoretical analysis results.