Development of Distance Relay Models for Real Time Digital Simulator

Abstract

This paper discusses how to develop a software model of the digital relay that can be added to real time digital simulator(RTDS) model library and is then subjected to the same outputs as the actual relay. The software model is stand-alone and can be used with actual relays. It is also possible to conduct interactive real-time tests when the system effects of the relay action need to be investigated. The characteristics of the mho type and the quadrilateral type, which are commonly used in recently developed relays, are modelled in this paper. Single circuit line and double circuit line system are used for model verification. The transmission lines are each 100 km in length and are modelled as distributed parameter lines but not frequency dependent. The transmission lines in the single circuit system are modelled as ideally transposed line. The mutual coupling data with the parallel line was taken account in the transmission lines for the double circuit system. CTs and PTs are included and operated in their linear region during the tests. For the purpose of testing the relay model accuracy the faults have been applied at various points on the protected line. Its accuracy is assessed against theoretical values.