Virtual testing of distance protection

Distance relays are the most commonly used protection devices in transmission systems. They require testing during different stages of relay development, commissioning, maintenance, configuration and operation analysis. The paper analyses the requirements for testing of distance relays under different abnormal conditions. It describes the conventional methods of testing and introduces a new method for virtual testing of distance relays. The virtual relay concept is described with several examples. Different applications of virtual relay testing and their advantages over conventional testing are presented at the end of the paper