GROUND FAULT PROTECTIVE RELAYING SCHEMES FOR DC TRACTION POWER SUPPLY SYSTEM

초록

In DC tracking power supply system, ground faults are currently detected by the potential relay, 64P. Though 64P relay detects ground fault, it cannot identify the faulted region which causes long traffic delays and safety problem to passengers. Three new ground fault protective relay schemes that can identify the faulted region are presented in this paper. One is bus differential protective relay for the rectifier bus protection and the other two are feeder ground fault protection relaying schemes. The two feeder ground protection relays use di/dt value. One uses it in estimating the distance to the fault location in multi zone distance relaying scheme and the other uses it to select faulted feeder in pilot directional permissive transfer trip relaying scheme. All the relays needs sufficient fault current for their operation. To provide enough fault current, ground switch is used in all the relaying schemes. EMTP simulation is conducted to validate their technical feasibility.