A Mathematical Optimization Technique for the Expansion of Electric Power Transmission Systems

Planning the expansion of a high-voltage transmission system involves deciding which new lines will enable the system to satisfy forthcoming loads with the required degree of reliability. Since these decisions involve considerable investment and operating costs, the planner will wish to keep the present worth of all costs as low as possible. The difficulties of the problem come from the tremendous number of possible alternatives, the need to make the best use of information about future loads, and the complexity of the reliability constraints: The outages of some specific combinations of lines (highest capacity lines among them, perhaps) must not at any time overload any other line in the system. A new computational procedure for system planning is presented; this procedure combines and optimizes the formerly separate computations of load flow, reliability analysis, and economic evaluation. This procedure has been applied successfully to a 17-node system studied by the Bonneville Power Administration.