Enhanced look-ahead load margin estimation for voltage security assessment

An enhanced method for estimating look-ahead load margin to voltage collapse, due to either saddle-node bifurcation or the limit-induced bifurcation, is proposed. The enhanced method contains improved schemes for accurately estimating the look-ahead load margins to bifurcation points. In addition, the enhanced method proposed in this paper can resolve the difficulty associated with the missing alarm problem. Two new strategies, sensitivity-based selection scheme and the reselection scheme are developed and incorporated into the enhanced method. The enhanced method is applied to a practical 3000-bus power system with promising results.