Simulation and algorithm development of protection scheme in DC traction system

This paper presents a simulation model of DC traction system which is based on bilateral power supply mode. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of short circuit current and the train starting current, more effective algorithms such as DDL protection has been proposed. The paper presents the principle and analysis of DDL protection scheme, which shows effectiveness of DDL protection for fault detection and discrimination against train starting currents in the DC transit system.