Longer-term voltage stability calculation by simulated annealing algorithm

An improved algorithm for global nonlinear optimization is presented. The scheme is based on combination of the nonlinear simplex with a simulated annealing (SA) algorithm. This improved algorithm is shown to provide faster execution time without compromising the quality of solutions obtained. The nonlinear simplex algorithm is adopted to decrease the amount of calculation. The results obtained reveal the adequacy of the algorithm for the global optimization of problems. Then the improved algorithm is adopted to calculate the longer-term voltage stability limit. Both nonlinear equality and inequality constraints for the longer-term voltage stability limit are considered. A sample system with a five-bus power system shows that the developed algorithm is effective and valid