Absorption Current Ratio and Impedance Hybrid Method of Fault Location for AC Railway Power Supply System

Due to the construction of new sections, existing overhead catenary systems are interconnected, there is no auto-transformers at the very end. In these last zone without AT at the very end, it is not possible to identify the fault location using conventional methods even if a ground fault occurs. When a ground fault occurs in such the last zone, the fault current is mostly absorbed by a AT located in the front side of the last zone. This characteristic is used to determine the fault zone. Since it is not possible to calculate the current ratio based on distance in the last zone, a reactance-based method is employed to pinpoint the fault location. In other zones, the existing absorption current ratio method is used.