Coordinated comprehensive design of distribution systems at medium and low voltage levels

Here, a method is proposed for primary and secondary distribution system planning in a coordinated hierarchy. The required data are supplied by a geographical data system, by a load-modeling program using the Handschin et al. linear model (1988) and Ganjavi et al. fuzzy neural networks (1999), and by a long-term load-forecasting program using trending methods of H.L.Willis et al. (1983). The “appropriate” installation time and place/route for new substations/primary feeders together with the expansion plan for new and existing substations and primary feeders are included in the planning process. Here “appropriate” implies the minimization of the present value of the design cost, or the maximization of the benefits-to-costs ratio as long as voltage profile and capacity constraints are not exceeded. The optimization algorithm uses bounded whole-count dynamic programming during a defined planning period and considers the cost of energy losses, the salvage value of equipment, the installation/removal cost of equipment and the energy price. A novel feature of the method is the automation of searching process. For the appropriate locations/routes of new substations/primary feeders based on engineering experiences