In this paper a long term planning for distributed generation and renewable resources is applied. The dependence on fossil fuel imports render the adoption and diffusion of distributed generation technologies and renewable resources a field of research increasingly recognized as important. This study contains both technical and economic feasibility of the distributed generation and renewable concept highlighting a set of items that must be investigated before this opportunity can be adequately pursued. Among them are understanding the technological impact, evaluating the kind of penetration in the distribution grid, developing planning procedures that incorporate dispersed generation into distribution systems, designing interfaces between distributed generation technologies and existing distribution systems. The above clearly requires adequate modeling, and the presentation will focus on this point. The experimental work is applied to Iran' Power system as a real power system. The planning results are presented and discussed.