Rough-Set-based timing characteristic analyses of distance protective relay

Nowadays protection engineers are suffering from very complex implementations of protection system analysis due to massive quantities of inconsistent data, let alone coming from diverse intelligent electronic devices (IEDs). Thus, a novel Rough-Set-based data mining strategy has been formulated to resolve the inconsistency in a distance protective relay's decision system (i.e. a transformed relay event report) in such a way that the relay's timing characteristics hidden in its decision algorithm of protection operations have been successfully discovered. Using Rough Set Theory, the inherent uncertainty and vagueness in the relay event report have been resolved using the concepts of discernibility, elementary sets and set approximations. The timing characteristics that have been successfully discovered are in relation to the relay trip assertion activity, impedance element activation, fault characteristics, circuit breaker operation and its overall decision system approximation. (C) 2012 Elsevier B.V. All rights reserved.