Protective relay testing and characteristic analysis for high impedance faults in transmission lines

This paper describes the relay testing method and the result for detecting availability of protective relays under high impedance faults (HIFs) in transmission lines. Mho type distance relays, quadrilateral type distance relays and PCM type current differential relays are selected for relay testing. Four kinds of model power systems including actual power systems to be used for relay testing are established in PSCAD/EMTDC. Each protective relay is tested using RTDS and RTPS. Boundaries of each operating zone are surveyed by testing. Availability of HIFs detection on relays are compared each other. Impedance variation characteristics at relay points are investigated using EMTDC in the case that source zero sequence impedance and load impedance are varied. The results shown in this paper can be used as an effective reference to install protective relay in real power system.