Abstract:A tree structure encoding partheno-genetic algorithm for distribution networks optimal planning is presented, and two new genetic operators such as shift operator and redistribution operator for tree structure encoding partheno-genetic algorithm are proposed in this paper, after the reason that the convergence of bintree structure encoding genetic algorithm can be generalized to tree structure encoding genetic algorithm has been given. Prim algorithm is employed to produce preliminary radial networks, which are better than entirely random schemes. The advantages of partheno-genetic algorithm are fully utilized in distribution networks optimal planning. All schemes in the solving process are always naturally being radial pattern, and no need for inspection of connectivity and being radial in connection of the networks. The determination of wire diameter, the treatment of street cross points and the method of expansion planning for distribution networks is discussed. The examples of distribution network planning show that the method is feasible and efficient. Finally, in the conclusion part, mutation operator has been proposed to perfect the tree structure encoding partheno-genetic algorithm.