Performance evaluation of an accelerated protection relay for distribution systems with tapped-off-loads

This paper presents a new technique for accelerated protection of distribution systems with tapped-off-loads. In the technique, the sequence component and super-imposed signals are used to detect the remote circuit breaker operation, from which whether a fault is inside the protected section can be derived. The paper introduces the design and relay implementation of the technique. Emphasis is placed on the laboratory tests of the relays using real time digital simulator (RTDS). Results show that the relays incorporating the proposed technique are able to significantly increase the speed of response of the conventional time grading based protection scheme.