Fast contingency screening for voltage-reactive considerations in security analysis

An efficient contingency screening method for voltage limit violations is presented. The Q-mismatches are calculated exactly for the buses situated in the vicinity of the out-of-service element and approximately for the buses that are electrically distant from the perturbation. In this step, the convergence rate of individual nodes outside the perturbation area is exploited and the small Q-mismatches are zeroed. The electrical distance concept is used to predict the buses on which major voltage shifts can occur after the contingency. Computational efforts are saved by using the approximate Q-mismatch calculations and by using the sparse vector techniques for the nonzero mismatches (fast forward back solutions). The number of bus voltages to be solved is greatly reduced, and the accuracy of the solution remains good. Results of tests with a 206 bus, 299 branch 400 kV reduced French network are given to illustrate the performance of the method