A hierarchical multi-objective capacity planning method for distributed energy system considering complementary characteristic of solar and wind

Distributed energy system (DES) integrated with renewable energy (RE) has attracted extensive attentions and developed rapidly for its high energy utilization rate and sustainability. Both solar and wind, as typical renewable energy, are usually considered in researches on DES while the complementary fluctuation charac-teristic of solar and wind is seldom taken into optimization objective during the planning process. This paper introduces a quantitative evaluation index of the complementary characteristics of renewable energies and proposes a multi-objective capacity planning method for DES to minimize the economic cost and to maximize the complementarity rate of fluctuation (CROF) simultaneously. To solve the established multi-objective model, a hierarchical optimization framework is employed, which remodels the multi-objective model into multi-layer optimization model by reconstructing new constraints. The nonlinear part of optimization model is linearized by linearization technique. Finally, branch and bound algorithm is employed to obtain the solution to optimi-zation model. Finally, case studies based on typical daily load characteristic curves in three kinds of seasons were performed and analyzed. The results verify the feasibility and effectiveness of proposed method, indicate that the complementarity rate of fluctuation can be improved by 53%, and the average relative fluctuation rate of power purchased from grid can be reduced by 58.7% compared with single economic objective model.