A Novel Framework for Optimal Sizing of A DC Microgrid Considering Energy Management and Battery Degradation

This paper presents a novel dual-layer framework to find the most economic photovoltaic and battery capacity combination of a grid-connected DC microgrid. The system cost during the whole lifetime is addressed in the optimization framework through the net present cost based objective function, where the investment cost, battery replacement cost and operating and management cost are taken into account. The proposed CAPN model, which combines all of the battery ageing stressing factors, is incorporated to estimate the replacement number of the battery. A particle swarm optimization algorithm, which is initialized with a rule-based power dispatch strategy, is put forward in the energy management level to achieve the optimal power dispatch. In order to adapt to variant operating conditions, the ambient and electric vehicle charging profiles throughout a whole year are employed as the input conditions of the optimization problem. A 61.8k RMB reduction is realized with the optimal configuration under the proposed method compared with the rule-based energy management strategy, indicating the superior of the proposed optimization methodology. Besides, the optimal power dispatch is also implemented with the extra power fed back to the utility grid.