Research On The Optimal Operation And Battery Capacity Configuration Of Electric Vehicle Battery Swapping Station Considering B2G Procedure

With energy shortage and environrment pollution becoming more and more obvious, the electric vehicles(EVs) have attracted more attentions of governments all over the world and many enterprises, due to their great advantages in energy saving and emission reduction. At the beginning of industrialization of EVs, the battery swapping staion(BSS) based on leasing mode is regarded as an important energy supply place for EVs. Thus, the research on issues relating to BSS is of great significance to EVs steady development. Based on analyzing the operation characteristics of BSS, this paper is focused on the optimal operation of BSS based on electricity market, the capacity optimization of batteries for BSS, and the coordination operation of BSS and power sysem under low-carbon economy. Some conclusions of the research work are summarized as follows.In this paper, the differences of EVs driving behavior between weekdays and weekends are studied based on the traffic data of private cars surveied by U.S. Department of Transportation. Meanwhile, the EVs swapping demand model with EVs weekly driving characteristics considered is presented. The scenario reduction algorithm based on the Kantorovich distance is used to reduce EVs swapping demand scenarios. On this basis, an optimal operation model of the BSS under time-of-use(TOU) electricity price is proposed. The reasonability and validity of the proposed model are proved by a case study on a certain BSS.After analyzing the state of charge(SoC) and operation characteristics of batteries in the BSS, a state transition model of batteries is proposed. On this basis, a capacity optimization model of batteries in the BSS under time-of-use pricing is developed to minimize the overall cost of BSS, which includes the investment cost, the maintenance cost, the charging cost and the discharging benefit of batteries. The proposed model is effective to evaluate the capacity requirement for batteries of EVs swapping demand and B2G procedure. A case study of a certain BSS is carried on, and the influences of battery price and power rate difference between peak and valley on the optimization results are analyzed.According to the flexible charging/discharging characteristics of BSS and the load fuature of power system in different periods, a multi-period BSS operation mode model is established, which can coordinate the power flow of generation system, power load and BSS. On the basis of the development status of carbon trading market in China, a unit commitment(UC) model of power system with BSSs in the low-carbon economic background is proposed to coordinate the G2B/B2 G procedure of BSSs with the production of each unit, aiming at achieving the minimal overall cost. With the relevant cost arising from emission allowance transactions in the objective fuction, the model proposed can evaluate the UC proplem under low-carbon economy effectivelly. The applicability and optimality of the proposed model are demonstrated by case studies based on a 10-unit test system. And the impact of BSS operation mode and CDM transactions price on the optimization results is discussed.