A Study on Modeling and Verification of the Percentage Differential Relay for the Protection of AC Electric Railway Feeding System

Abstract

In general, a Scott-transformer is used to supply the single-phase power for the Korean AC electric railway feeding system. In particular, the Korean Autotransformer feeding system has a different configuration compared to those of other countries, therefore, it has certain distinctive characteristics. In addition, a percentage differential relay is widely and globally utilized for protecting the transformers. However, detailed modeling and simulation for the relay protecting the Korean AC electric railway feeding system is not performed enough. Thus, in this paper, we modeled and verified the percentage differential relay for AC electric railway feeding system by using PSCAD/EMTDC. A simple method to prevent malfunction due to a saturation of the current transformer is suggested as well.