A new power sensitivity method of ranking branch outage contingencies for voltage collapse

The objective of this paper is to present a powerful procedure for identifying severe single branch outage contingencies with respect to saddle-mode bifurcation induced voltage collapse, given a power system operating point, a load demand forecast, and a generation dispatch. The new Power Sensitivity Ranking Algorithm for voltage collapse, called lambda/MVA Sensitivity, provides more accurate "distance to collapse" estimates than linear admittance sensitivity, yet requires only slightly more computation time. The distinguishing features are the ability 1) to rank all branches in a large-scale power system quickly and 2) to estimate the outage contingency bifurcation values accurately. As an illustration, the new lambda/MVA Sensitivity Ranking Algorithm can estimate all 6689 single branch outage contingency bifurcation points (lambda(ctgc)(*)) of a 3493 bus power system within 3% relative error, except for two branches within 7%, in less than 4 min on a 180 MHz PentiumPro PC.