LAUSR

This paper presents a methodology to perform application tests in protective relays. It is based on using the Gabriel graph to select, from a large number of events generated by a Monte Carlo-based procedure, a smaller subset that is able to predict the relay performance without compromising the quality of the estimator. The proposed methodology is successfully applied to test the behavior of differential protective relays in two situations: turn-to-ground faults and transformer energizations. In both cases, the proposed methodology significantly reduces the number of tests required to predict the success rate of the tested relays for a desired confidence level and variance. It is observed that the efficiency of the method increases as the estimated success rate of the relay increases. This means that if the estimated success rate is high, the proposed methodology leads to larger reduction in the number of events that are actually necessary to test the relay. The validity of the proposed methodology is demonstrated by means of tests performed with an actual protective relay.