Application of simulated annealing algorithm to voltage stability calculation

In order to improve the efficiency of nonlinear optimization method, a new algorithm based on combination of the nonlinear simplex with simulated annealing (SA) for global nonlinear optimization is presented. This improved algorithm provides faster execution time without compromising the quality of solutions obtained. The improved algorithm is adopted to calculate the longer-term voltage stability limit. The interior point method and the penalty function are chosen to solve nonlinear equality and inequality constraints in the static voltage stability calculation. A digital test for a sample system with five-bus shows that the developed algorithm is effective and valid.