A Novel Fault-Location Algorithm for AC Parallel Autotransformer Feeding System

In general, an autotransformer (AT) is used to improve the voltage sag and inductive interference in power lines and communication lines in the Korean ac electric railway feeding system. In particular, the Korean AT feeding system has a different configuration compared to those of the other countries, such as Japan or France; therefore, it has certain distinctive characteristics. However, a fault locator imported from the other countries has been used in Korea, and the settings of these equipment should be modified and reflect the distinct characteristics of the Korean AT feeding system. Thus, the development of a novel fault-location scheme for the Korean railway system is required. Herein, we analyzed the fault current and developed a specific relationship for use in our new algorithm. We presented the current magnitude of each branch, expressed by the boosting current of the ATs; further, the novel fault-location scheme using this relationship is developed. The novel scheme performance is verified through power system computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) and the field measured data.