Line outage ranking for voltage limit violations with corrective rescheduling avoiding masking

This paper describes a technique for ranking line outages causing voltage limit violations taking into account the post-outage correctability of the network during contingency selection process. Due to the choice of large even powered of performance index (PI): (i) masking is avoided; and (ii) complete potential of correctability of power network is utilised. Fletcher and Reeves conjugate gradient method is used for optimisation. Use of newly derived compensated voltage shift factor has been made. To restrict the reactive power limit violations at generation buses, use of newly derived reactive power compensated shift factor has been made. Control corrections have been optimised for each line outage in the same base case pre-outage condition itself. This allows the use of same set of pre-outage sensitivity coefficients and line outage distribution factors. It is to be stressed here that the control corrections have been obtained for each line outage in pre-contingency condition mainly for computational convenience. But actually these corrections are applied in respective postoutage conditions. The algorithm is tested on IEEE 25-bus, 30-bus and 91-bus test systems.