Research On The Adaptability Of Large-scale Electric Vehicle Charging (Discharging) Stations And The Grid

Along with continuous development of electric vehicle (EV) technology and charging facilities, EV will be increasingly used in people's lives. EVs have to get energy from the grid, resulting in charging load. When EVs and charging stations reach to a certain scale, charging load would be very large and cause a certain influence on the grid. In order to ensure the grid meet the charging needs of EVs, avoiding and reducing their adverse effects on the normal operation of grid, it is necessary to study the adaptability of large-scale charging stations and the grid.Charging load estimation of fast charging station and battery replacement station under the charging time program is studied and load profiles are analyzed. Charging load of large-scale charging stations is estimated as well. The result shows that charging load of special charging station for electric bus is mainly in grid valley time at night, which is conducive to narrow the peak-valley difference, while charging load of fast charging stations and battery replacement stations is mainly in grid peak and other time, which is less in grid valley time, is not conducive to the grid peak load shifting. Based on normal distribution theory, the distribution of charging load under the natural state is analyzed and a certain universality of the load model is established, which can be applied to the estimation of charging load.Combined with existing data, for a period of 5 years, EV and electric bus population of the four stages from 2015 to 2030 in Beijing is estimated. Corresponding charging load is estimated depending on the development of battery technology and charging facilities. The corresponding load of Beijing grid is also estimated.The influence of charging load on grid load is researched. The result shows that along with the development of charging stations, the impact of charging load on the grid gradually increases. The load of fast charging and special charging station for electric bus are relatively regular while load of charging point has certain randomness when superimposed on the grid load. The total charging load produces a certain degree of influence on the grid load.Considering charging/discharging stations with V2G function, they can achieve a variety of functions once the time arrived. Different charging scenes are chosen to analyze charging load and application of different V2G functions.