Abstract: In this paper a mathematical model for distribution network reactive power planning was established to solve the configuration capacity by taking the minimized sum of electrical energy loss at the different load operation mode and the investment for reactive power compensation equipments as the objective function. Meanwhile, the evolution strategy is improved. In order to better introduce competition mechanism and achieve population diversity, double populations and‘catastrophe’ are introduced. Different fitness functions is used respectively for the two populations to choose next generation, and the fitness is improved to ensure the diversity of population and the accuracy of the fitness values. Chaos search is introduced in the elite group to jump out of local convergence. A case study is conducted by use of improved evolution strategy method and results show that the improved algorithm has better global search capability for optimization.

Key words: distribution network, evolution strategy, fitness, chaos search, reactive power planning