Comprehensive Framework for Long-Term Distribution System Planning

System designers typically use intuitive, knowledge based, or heuristic methods in long term distribution planning. While there are no faults to this approach, room is left for improvement from an optimization (and cost) perspective. This paper presents a long-term, system based, optimization approach to distribution systems planning for existing system configurations. Applicable to both radial and loop/grid systems, this approach allows substation, feeder, and distributed generation upgrades while accounting for line limits, technology limitations, varying energy prices, environmental (emissions) limits, and zoning restrictions. Constructed as a mixed integer nonlinear programming (MINLP) model, only recent advances in operations research have made solving such a problem even possible. This model is tested on a 9-bus radial system and analytical results are presented.