Performance analysis of the enhanced zone 3 distance relay on WSCC test system

The algorithm to enhance a zone 3 distance relay, employing transient components and state diagram, which has been proposed by [1] is an outstanding concept. Verification of its performance on a real power system is the next important step before actual implementation. This paper examines crucially distinct operational functions of the enhanced zone 3 distance relay using the 9-bus WSCC test system, where dynamics of synchronous generators, excitation systems, and governer controls which could have an impact on the identified transient components, are also taken into account. Simulated test results herewith confirm that with this embedded algorithm the zone 3 of a distance relay can differentiate line overload from short-circuit fault, and in turn critical false tripping which could accelerate system blackout can be avoided. Furthermore, when the line overload is immediately followed by short-circuit fault, the latter takes higher priority, and the back-up protection of a distant line effectively remains, still.