Selective protection strategy for short-circuit faults in LVDC distribution system

Low-voltage direct current (LVDC) power distribution system is receiving more and more attention due to its good power quality and high efficiency of new energy grid connection. However, the LVDC fault protection, which is one of the key issues of DC power distribution technology, has not been solved. Based on the radial LVDC power distribution system, this paper analyses the short-circuit current characteristics, and in order to solve the problem of fast rising fault current of LVDC bus, the current limiting strategy based on the current closed-loop control is adapted. Then according to the fault current characteristics of different short-circuit points and different load ratios, the selective protection strategy is proposed to realize the selective operation of the upper and lower circuit breakers to improve the reliability of power supply. Finally, the feasibility of selective protection strategy under different short-circuit conditions is verified by PSCAD/EMTDC simulation, and the results show that the DC fault can be selectively cleared to guarantee the normal operation of healthy lines.