Study On Control Strategy Of Electric Vehicle Battery Charging And Swapping Station In Grid Frequency Regulation

The scale of electric vehicle is growing in recently years because of its low emission and high performance. The charging infrastructure network for electric vehicles will be constructing everywhere in the future. The electric vehicle battery charging and swapping station can provide charging service, battery-swapping service and also can be regarded as energy storage power station. The charging and swapping station integrate in the grid which can act as controllable loads and energy storage systems to supply ancillary service such as frequency regulation. Help the power grid to suppress the fluctuation of frequency and reduce the impact of new energy sources such as wind and solar integrate in grid. Therefore, it is of great theoretical and practical importance to research the control strategy for charging and swapping station participates in grid ancillary services.This paper focuses on the research of control strategy and method of power distribution, the main research content as follows:Firstly, this paper analyzes the basic principle of frequency regulation. Compare with traditional regulation methods, the charging and swapping station integrate in the grid to supply ancillary services has many advantages, describes the two differences realization methods of frequency regulation, analyzes several important issues about the frequency regulation.Secondly, this paper analyzes the topology of charging system and chooses suitable main circuit topology considering the characteristics of frequency regulation system. Calculate the main parameter in main circuit topology. The batteries are set to different level of response to avoid overcharge or over discharge.Thirdly, this paper calculates the available power capacity for regulation based on the SOC of the battery to ensure the charging and swapping station participate in grid frequency regulation effectively. Design a distribution method of power in different abnormal situation to reduce the overcharge or over discharge of the batteries.Fourthly, this paper proposes the corresponding control strategy for charge and discharge in different modes, experiments based on WSCC mode is carried out for two cases of the rise and fall of frequency. The results verify that the charging and swapping station can accurate response the power request from the gird when the frequency is disturbing.Finally, this paper designs the hardware and software of the frequency regulation system, and verifies the reliability of the system through experiment. The research of this paper could provide a reference for charging and swapping station integrate in the grid to supply ancillary services.