Abstract
Recently, distributed resources are increasingly connected to distribution networks and management of the voltage distribution system has become more difficult. As a countermeasure, it is necessary to properly adjust the transformer tap setting of pole transformers in order to increase the ability to manage the voltage. However if the taps of a pole transformer is modified, it becomes necessary to reexamine and adjust the parameters of the voltage control equipment and to carefully arrange the equipment in the distribution system. Optimizing the configuration of the distribution system becomes more important, however, the problem is very complex and there has been no excellent solution until now.
In this paper, we propose a method to manage the feeder voltage of a distribution network by optimizing the pole transformer tap setting. The voltage profiles are calculated by load flow calculation under the several conditions that the load is heavy or light, the output of the distributed generators (DG) are maximum or minimum. The tap setting of the pole transformer, setting point of the step voltage regulator (SVR) and sending voltages of the feeders are decided in a way that satisfies the voltage constraint 101 ± 6V for each load condition. The problem is formulated as a combinational optimization problem. The optimum solution can be obtained by using branch-and-bound search method with effective bounding operations. The outline of the algorithm and calculation examples using a sample feeder are also described in this paper.
