DefinePK

Abstract

In this present paper, a computationally realistic algorithm is adopted in order to obtain the critical clearing time (CCT) by means of one machine infinite bus (OMIB) equivalent system which has been derived from an equal area criterion (EAC). The CCT is defined as the highest time intermission by which the fault ought to be cleared with the aim of preserving the power system stability. The computation of CCT entails an essential numerical formulation derived from the three fault conditions, which are; pre-fault, during fault and post-fault conditions. The significance of CCT becomes considerably less whilst transient instability is induced by a three phase fault occurred at the bus bar next to the substation connected with a sensitive generator. By setting the protection relay with the obtained value of CCT, it is sufficient to maintain the transient stability albeit fault occurred at other locations. Throughout the occasion of fault, a circuit breaker which is in service earlier than the smallest CCT will not agitate to a transient instability. The IEEE Reliability Test System 1996 (RTS-96) is used to validate the robustness of the proposed methodology in determining the CCT.