Distribution expansion planning in the presence of plug-in electric vehicle: A bilevel optimization approach

Abstract

Popularization of plug-in electric vehicles has changed the traditional strategies for distribution expansion planning problem. Therefore, considering the high penetration of electric vehicles, it is necessary to propose new models and strategies for this problem. The present study proposes a new multi-stage model to expand the distribution network based on the bilevel optimization taking the plug-in electric vehicles into account. In the upper level, whose objective function is the total annualized investment cost plus annual expected production and maintenance cost, the investment and utilization decision variables are identified. In comparison, in the lower problem, whose objective function is the cost of purchased energy from the main grid, the daily optimal scheduling is determined. By using primal-dual formulation, this bilevel optimization is recast as a mixed-integer linear programming problem, which can be solved by off-the-shelf solvers. A 24-node distribution network is used to show the efficiency, tractability, and economic advantages of the proposed methodology. The results indicate that the DEP with the smart charging strategy will lead to less investment cost compared with the case in which the dumb charging strategy is utilized. In addition, the results show that the optimal solution of the proposed bilevel model is superior to the optimal solution of the model in which the smart charging problem is solved in a separate optimization problem.