Detection of cross-country fault on distance protection

Abstract

Distance relay is one of protection components in transmission line. It is widely used as the main protection that gives a tripping signal to the Circuit Breaker (CB) when the fault occurs in the system. When short circuit faults occur in transmission line, the distance relays provide the protection and trip the CB by disconnecting the faulty portion from the healthy section. The main purpose of this research is to find the detection of Cross-Country Fault (CCF) on Distance Protection (DP). During this CCF condition, the faults are in an abnormal condition. This research is performed on a simple circuit model and IEEE test system with 6 buses, 9 buses and 14 bus systems. By using PSCAD/EMTDC software, the Mho characteristics and Bergeron model type of the transmission lines are modelled and have been simulated to generate the output current and voltage that are used to calculate the reach impedance for protected Zone 1. From the simulation results, it can be observed that the fault voltage and current are almost at the same values with the previous research on the normal fault. It means that the voltage and current will become highly fluctuated during the CCF condition. The result analysis is based on CCF with different locations at the same voltage level and CCF with different locations at different voltage levels. To study the performance of CCF condition, the outputs of all types of fault were considered in this project. It is found that the relays in most of the fault’s conditions are operated in the protected zone. Finally, it can be concluded that the effect of CCF on DP are successfully identified.