Study On Distribution Network Reconfiguration Based On Improved Harmony Search Algorithm

Serving as one of the important measures to facilitate optimal operation of distribution systems, distribution network reconfiguration is lucrative in both economic and social benefit. It is a complex combinatorial optimization process aimed at finding a radial operating structure that minimizes the system power loss, balances the overload of the network, and improves the reliability of power supply while satisfying operating constraints.This paper mainly focuses on a new method based on improved harmony search algorithm (IHS) to solve network reconfiguration of distribution system for power loss reduction, and encoding strategy of harmony and alteration of algorithm parameters are also studied in this paper. Firstly, The objective function of distribution network reconfiguration is established as minimizing the network loss. Following analysis of topological identification of distribution network with breadth-first algorithm, this paper establishes node-layer matrix and father-node matrix, and conducts load flow calculation with forward and back/forward substitution method based on node-layer. Secondly, After explaining basic principles of harmony search algorithm, this paper introduces renewal mode of harmony memory considering rate (HMCR) and pitch adjusting rate (PAR) based on self-adaptive regulation to address problems of low convergence rate in early stage and local optimization at later stage. Consequently, search velocity has been greatly enhanced. Thirdly, during the solving process, combining structure of distribution network with decimal encoding strategy based on enclosed loop of harmony helps to shorten code length and narrow search area of feasible solution, while excluding infeasible solution with basic area structure of graph theory in order to increase the search capability of algorithm.Finally, the results after reconfiguration of two typical distribution networks are given. Compared with the result of genetic algorithm, it illustrates the proposed algorithm has less iterative times and faster calculation speed, and verifies feasibility and effectiveness of improved harmony search algorithm for distribution network reconfiguration.