Multiple-objective dg optimal sizing in distribution system using an improved PSO algorithm

An improved particle swarm optimization (PSO) algorithm has been presented in optimal sizing of multiple DG units in this paper. Firstly, multiple-objective functions have been formed with the consideration of minimum line loss, minimum voltage deviation and maximal voltage stability margin. Through fuzzy set theory, the multiple-objective optimization problem has been transformed to single objective comprehensive optimization with membership degree. The global particle swarm optimization algorithm dominates the search direction and works out the result; in the meanwhile, the inertia weight w, the cognitive and social parameters are updated in adaptive mode. And multi-initialization method is utilized to refresh the particle populations and increase its diversity. Several experiments have been made based on the IEEE 33-bus, actual 292-588 and 1180-bus test cases with the consideration of multiple DG units. The computational result and comparison indicate the proposed algorithm for optimal sizing of DG in distribution system is feasible and effective.