Distribution network expansion planning is one of the most important prob- lems in power systems. Modeling distribution network expansion planning in the presence of distributed generators needs new requirements to model the renewable energies, electricity price, and demand uncertainties. In this paper, 2 risk indices are proposed: (1) If a scenario is flexible, it requires a relatively low investment, introduced as adjustment cost, to attain the efficiency of the opti- mal solution in other scenarios (ie, flexibility criterion) and (2) if the maximum distance of a solution is minimum from the optimal solution of all scenarios, then the scenario is robust (ie, robustness criterion). The resulted model is a multiobjective mixed-integer nonlinear problem, which is solved using non- dominated sorting improved harmony search algorithm-II. To obtain the final plan, the fuzzy decision-making analysis is applied, and to demonstrate the effectiveness of the model, it was applied to 9-node and 69-node distribution systems.
