Research On Secure And Intelligent Interaction Technology Between Cluster Electric Vehicles And Power Grid

With energy problem increasingly serious,electric vehicles have been vigorously promoting due to superior energy-saving and environmental protection characteristics such as zero emissions,low energy consumption and zero pollution,but with the rapid growth of electric vehicle ownership in China,large-scale disorderly charging of electric vehicles has brought great challenges to the safe,economic and stable operation of the distribution network.Therefore,it is particularly vital to carry out the evaluation of the charging load acceptance capacity of electric vehicles in the distribution network and the secure interaction strategy between electric vehicles and power grid.The main research contents of this paper are as follows:(1)The factors affecting the charging load of electric vehicles are analyzed,electric vehicles are classified by use,and the charging load of various types of electric vehicles is modeled taking into account the unique charging behavior of electric taxis and buses at noon,and the charging load time distribution of various types of electric vehicles at different scales is simulated,and the simulation results show that random charging of large-scale electric vehicles will increase the power supply pressure of the power grid,and the charging behavior of various types of electric vehicles is different due to the differences.Therefore,the total charging load curve has the characteristics of multiple peaks.(2)Based on the impact of disorderly charging of electric vehicles on power grid,the acceptance capacity of power grid for electric vehicles under different access modes is analyzed.Based on the established prediction models of various electric vehicle charging loads,the acceptance capacity of the distribution network for electric vehicle charging load is evaluated and analyzed by introducing the maximum load capacity of the system,the nodal voltage deviation and the static voltage stability margin,and the specific steps of the evaluation method are given.Finally,taking the IEEE-33 node distribution network system as an example,a variety of simulation cases are set up,and the maximum access scale of electric vehicles in different seasons is obtained,and the static voltage stability margin of the distribution network under the maximum electric vehicle access scale is analyzed.(3)The two-layer optimization strategy of electric vehicle and grid security interaction is studied.Firstly,the concepts of time-of-use electricity price and real-time electricity price are analyzed,the characteristics of the two electricity price models are compared,and a two-layer optimization model for the safe interaction between electric vehicles and the power grid is constructed.The upper model adjusts the charging price of electric vehicles in each period according to the regional grid load,and the lower-level optimization model,based on the charging price data transmitted by the upper model,optimizes and schedules the charging load taking the total charging cost of users and the total peakvalley difference of load as the objective function.The optimization results show that the secure interaction strategy proposed can better reduce the charging cost of electric vehicle users,achieve the optimization goal of reducing the peak-valley difference of system load,effectively alleviate the climbing power problem caused by disorderly charging load,reduce the impact of disorderly charging behavior of electric vehicles on power quality of power grid,and also bring greater economic benefits,thereby promoting the safe and economic stable operation of regional power grid.