Decoupling algorithms for unit commitment based on modification of particle swarm optimizatio

Due to the difficulty of achieving optimal solution theoretically, unit commitment (UC) is a hard task in optimal operation of power system. For this reason, in this paper a decoupling algorithm based on the modification of particle swarm optimization (PSO) is proposed. Firstly, by use of Lagrangian relaxation algorithm based on aggregative projection sub-gradient the dual solutions of UC is obtained; then according to the reserve multiplier and dual combination in dual information, the optimal space of particle swam is built; and then by use of unrestricted standard PSO algorithm the local updating of Lagrangian multiplier is implemented, by means of adjusting particles and the information transmission among particles the UC is changed, after that the Lagrangian dual solution is modified and finally the approximate optimal solution of UC is obtained. The solving speed and calculation accuracy of the proposed method are verified by simulation results of six test systems.