Research on Capacity Optimization of Hybrid Energy Storage Charging Station

To reduce the peak power caused by fast charging of numerous electric vehicles, and to decrease the cost of fast charging stations, a hybrid energy storage system composed of super capacitors and lithium batteries, corresponding to high power density devices and high energy density devices, respectively, is developed to improve the economic benefit of charging stations and alleviate the load fluctuation by properly allocating the capacity of energy storage. A mixed integer nonlinear model is built to evaluate the optimal configuration of the hybrid energy storage system, by minimizing the total cost of the fast charging station and establishing the real-time power balance, along with the working state of the energy storage system as constraints. A two-stage cooperative optimization algorithm is proposed to solve this model. The simulation results demonstrate that the peak power can be significantly reduced, and the total cost of the fast charging station can be effectively reduced, which validates the feasibility of our proposed capacity configuration model and algorithm.