Research On Gird-connected Control Strategy Of Battery Energy Storage In Electirc Vehicle Charging Station

With the increasing depletion of fossil fuels and growing environmentalpollution, electric vehicles are attracting much attention and favor because of the useof secondary clean energy. At the same time, electric vehicle charging electricalsystems and equipment have also been developed rapidly. Therefore, in order topromote the development of the electric vehicle industry, the State Grid Corporationof China is building energy unified supply system, electric vehicle charging station, toelectric vehicles in accordance with the "replacing the battery mainly, chargingauxiliary, centralized charging, unified distribution " mode. After the large-scaleconstruction to the electric vehicle charging station, the battery energy storage systemcan exchange energy bi-directionally to urban distribution network. It will achieve toload shifting, improve system stability, stabilize power fluctuations and improvepower quality. This paper established on industrial support projects in HunanProvince——Research on city distribution network power quality and flow controlbased on the electric vehicle charging station. The main researches are as follows:At first, this paper summarized the research and the development status of EVcharging station and discussed the development of the EV charging station in ourcountry. Then, reviewed the advantages and disadvantages of energy storage systemsapplied to power system. And this paper proposed battery energy storage in electricvehicle charging station connected grid.Then, the battery energy storage system and network topology of thegrid-connected system are analyzed. Two topologies of single-pole and multi-poleabout grid-connected the battery energy storage system are introduced in details:. ATlast, this paper chooses a topology which has the function of energy-storedbi-directional converter connected to multi-batteries.The difficulties of system of EV charging station grid-connected including thethree-phase PWM inverter control, the bi-directional DC-DC converter control andhow to both coordinated control. Therefore, network topologies, working principlesand mode of operation of three-phase PWM converter and bi-directional DC-DCconverter are analyzed in details. At last, this paper focuses on designing keyparameters such as the DC link capacitors, AC filter, DC inductor.Next, the research on control method of the network system are carried out. According to the principles of three-phase PWM converter and DC-DC convertercontrol strategies, the methods of power decoupling and constant current control areadopted respectively. The simulation model of battery energy storage grid-connectedsystem is established in MATLAB software. The simulation results verify thefeasibility of the control strategy.At last, hardware system about the main circuit of grid-connected control systemis designed, and the design control circuit of it is focused on.