Distribution System Planning Evaluation Method Using Voronoi Diagram and Tabu Search

Distribution planning must be carried out by considering (1) geographic information such as allocation of loads and feeders, (2) operational conditions such as line current capacity, voltage drop limit and distribution loss, and (3) facility cost and so on. In order to systematically support the above work by computational approach, optimization techniques are available. In this paper, a computational method to support distributional planning systematically is proposed by introducing (1) geographical optimization technique and (2) configuration optimization technique. The geographical optimization is to determine which of sectionalized lines should supply power to future appeared loads so as to maximize availability ratio of feeders. The configuration optimization is to determine states of sectionalizing switches (opened or closed) so as to minimize distribution loss under the constraints such as the line current capacity, voltage drop limit and radial structure. In the proposed method, after the geographical optimization is carried out to determine future section loads, operational conditions are evaluated by the configuration optimization. If the operational constraints are not satisfied, previously prepared expansion plan candidates are evaluated quantitatively, and then the best candidate is decided. Voronoi diagram is applied to realize the geographical optimization, and tabu search is used to accomplish the configuration optimization. In order to check the validity of the proposed method, numerical results are shown for a distribution system model.