Fuzzy based contingency assessment using performance indices with masking effect

Nowadays the Stability of the power system has become very vulnerable due to frequent voltage instability. Contingency assessment has to be carried out to figure out the lines which are most vulnerable to instability. In this paper contingency assessment is done by a novel technique in which performance indices (PI) obtained from the variation of bus voltage magnitude and apparent power of the transmission line are taken into account with masking effect. The overall ranking of the severity of the contingencies is obtained through fuzzy logic. For this purpose we propose a three step technique: in first step the performance indices are obtained through power flow; in second step the masking effect is removed; fuzzy logic based overall ranking is obtained in the third step. The approach is illustrated on IEEE 14 bus system. This approach is suitable for different types of plots. By knowing the severity of the contingency the operator can sketch a control action in the real time before the system moves towards instability.