Analysis of Urban Rail DC Short Circuit Fault and Vehicle-Network Protection Coordination Based on Transient Characteristics

During the operation of urban rail transit system, if the vehicle traction system has short-circuit fault, the vehicle protection device will act and cut off the short-circuit current. Under some extreme short circuit conditions, the protection device of power supply system will also act, and the whole power supply section will be powered off. This is because the action setting values of vehicle protection device and power supply system protection device are designed respectively, and their matching and reliability need to be analyzed. Based on this, this paper first models the urban rail transit power supply system and vehicle traction system, then compares the calculated mathematical model with the simulation model to verify the accuracy of the simulation model. Finally, the short-circuit current waveforms under different short-circuit conditions are simulated, and the action sequence and protection range of protection devices are analyzed according to the simulation results. The research results are of great significance to the characteristic analysis of short-circuit fault, the selection of vehicle protection devices and the setting of protection parameters of power supply system.