Multi-Objective Distribution Network Reconfiguration Based On NSGA-Ⅱ

Distribution network reconfiguration is an important part of distribution automation. It serves as a good choice in maintaining distribution network operation economy and improving power supply quality as well as power distribution reliability. During the normal operation of distribution network, eliminated overload, along with balanced load and optimized power losses can be realized through changing network structure and adjusting on-off state of switches. Facing the failure of distribution network, the failure can be isolated and power restoration shall be rendered on non-failure load to the greatest extent so as to reduce the power failure area.In the paper, based on the development trend of distribution network and taking into consideration distribution network economy, safety and reliability, it can be concluded that distribution network reconfiguration is a multi-objective optimization problem, which is a new research area in distribution network reconfiguration. On the basis of summarizing the previous researches, the following aspects are completed in the paper:First of all, development status of distribution network as well as the method of distribution network reconfiguration is analyzed in the paper. According to the requirements of multi-objective optimization for distribution network reconfiguration, three objective functions are raised in the paper, namely optimal active network loss, minimum node voltage offset as well as equalized load. Those aspects relate to distribution network economy, power quality and safe reliability.Besides, basic principle of genetic algorithm (GA) is expounded in detail. Moreover, the advantages and disadvantages of solving distribution network simple objective and multi-objective optimization concerning GA is analyzed. Due to that simple GA renders bad effect in managing multi-objective distribution network reconfiguration and weight coefficient exerts great influence on the result, NSGA-II, based on fast non-dominated sorting stratification is adopted so as to conduct non-dominated sorting stratification on population individuals. In this way, global optimum of the individuals can be realized, the Pareto optimal leading edge can be found, and Pareto optimal solution of multi-objective distribution network reconfiguration can be obtained. In order to improve the search efficiency, a method of filtering "illegal" individuals in a population is put forward. Besides, incidence matrix for distribution network node and edge is established. After the removal of any row vector, it can be decided whether the individual can satisfy the radiation structure of distribution network through judging the linear correlation of the remaining row vectors in the matrix.At last, fast non-dominated GA is employed in distribution network configuration of 16-node as well as the 69-node of PG&E. According to the computed result, it is shown that NSGA-II (combining the features of distribution network) is provided with good global searching ability. It can effectively reduce network loss, improve node voltage, balance the load and verify the practicability of NSGA-II in distribution network reconfiguration.