Optimal Distribution Substation and Primary Feeder Planning VIA the Fixed Charge Network Formulation

The planning methodology presented in this paper is an application of recent advances in optimization techniques for distribution substation siting and radial feeder planning. The concept of a long range horizon year (target) is used together with a time-phased expansion process beginning with the base year and progressing to the target year. An optimal static horizon year design is first determined using a fixed charge transshipment problem formulation (FCNP). The FCNP solution methodology employs the branch-and- bound algorithm and includes explicit modeling of fixed charge and variable cost components for improved accu- racy. The time-phased expansion process selects substation sites and feeder routings from the horizon (or target) year plan, thus providing an orderly and coherent expansion. This method easily incorporates existing facilities in the decision process for maximum benefit. An example of an actual planning study is presented to illustrate the horizon year target system selection and the corresponding time-phased expansion patterns.