Optimal reactive power planning using GA/SA/TS hybrid approach and decomposition and coordination theory

A sum of the cost of active power losses and reactive power generating equipment is used as the objective function of optimal reactive power planning (ORPP) problem. The theory of decomposition and coordination is employed to decompose the problem into three sub-problems according to load level. Every sub-problem is a problem of reactive power optimization, which is solved by a hybrid approach of GA (generation algorithm), SA (simulated annealing) and TS (tabu search). The approach adopts the acceptance probability of SA to improve the GA by avoiding being trapped by a local optimal solution. GA/SA offers a good initial solution for TS. Three sub-problems are coordinated by the heavy load loss time of one year. During the coordination iteration, a memory scheme is utilized to memorize the best solutions of every sub-problem, which promises better results. A 137-bus practical area power system with 79 control variables in Shandong province of China has been tested to show the effectiveness of the planning method.