(1. College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China;2. Electric Power Research Institute of State Grid Zhejiang Electric Power company, Hangzhou 310014, China)

A novel integrated plan optimization method of grid-connected microgrid is presented with the objective to minimize the life-cycle cost. The proposed method is based on joint optimization of optimal sizing and operating considering the grid-connected performance index. Firstly, the self-balancing level, redundancy level, RES utilization level and other indexes are defined to evaluate grid-connected performance as constraints on the optimization method. Secondly, the sizing optimization would be done in multiple random scenarios to deal with the indeterminacy of solar and wind resource based on scenario generation and reduction. Finally, the simulation results based on the actual data on the microgrid project are presented to demonstrate the performance of the proposed approach.