Abstract:
Distribution system planning is an essential problem of a distribution utility. Appropriate distribution system planning is recognized as a complex problem due to a large number of customer load points. The dissertation proposes a method for solving radial distribution system planning problems. It consists of four main steps, i.e. 1) determine appropriate substation locations, 2) determine optimal routing, 3) select optimal sizes of feeders, and 4) select optimal substation capacity. With this proposed method the appropriate location and size of a substation, routing of feeders, and appropriate sizes of conductors can be automatically selected. Moreover, the existing infrastructure and geographical constraints, e.g. streets, canals are also taken into account in determining the results. In addition, another important problem of the distribution utility concerns the protection system design. To serve its customers with high reliable and low cost of power supply, the utility must design an effective protection system. This dissertation proposes a method for identifying number, types, and locations of the protective devices in order to minimize overall system cost. The system cost includes investment cost and customer interruption cost, both for permanent interruption and momentary interruption. The developed methods have been tested with an actual distribution system in Thailand, and the RBTS which has been widely used internationally. The results clearly illustrate the impacts of the geographical constraints and the momentary interruption cost.