Traditionally, power system planning problem focuses on finding the least-cost generation resources including typical conventional fossil fuel based units without paying attention to a complete set of available generation portfolio alternatives. The predominant share of conventional fossil fuel units in power generation sector has increased concerns on climate changes, energy security, and price volatility . Having these challenges in mind, many power systems have started changing their generation portfolio including significant amounts of renewable energy resources toward a sustainable energy development.This paper presents a comprehensive approach for Generation Expansion Planning (GEP) problem in the presence of Distributed Energy Resources (DER). Different support schemes for DER investors are considered and their impacts on sustainable development are modeled. Regarding this matter, several indicators are presented for evaluating different aspects of sustainable development achievements. Moreover, a decision making framework is proposed using a combined fuzzy Analytic Hierarchy Process (AHP) and Technique for Order Performance by Similarity to Ideal Solution (TOPSIS). The effectiveness of the proposed framework is assessed by a numerical study on a test system.