Influence Of Electric Vehicle Access Mode On Voltage Stability Of Distribution Network

The charging load of electric vehicle has the characteristics of randomness,fluctuation and source load duality.Its large-scale disordered access will have a serious impact on the safety and stability and economic operation of distribution network.Once the explosive growth of charging facilities occurs,the maladjustment of the current power grid will seriously restrict the development of electric vehicles.Firstly,this paper divides electric vehicles into three different types:bus,taxi and private car,and analyzes the behavior characteristics of different types of electric vehicle owners.The demand model of electric vehicle charging load is established based on Monte Carlo stochastic simulation method.M language program is written to predict the power demand of a certain number of different types of electric vehicles based on MATLAB simulation software.The results show that when the large-scale disordered access of electric vehicles to the distribution network,it may lead to the increase of peak valley difference,peak time shift and peak duration.Secondly,the influence of electric vehicle charging load on the voltage deviation of distribution network is analyzed.The voltage deviation changes with time before and after the connection of electric vehicle and the participation of electric vehicle in V2G are compared.The mathematical model of static voltage stability is established from two aspects:the existence of power flow equation solution and the anti disturbance ability of the system.The results show that the large-scale disordered charging of electric vehicles will have a serious impact on the voltage stability of the distribution netwo rk,such as the increase of the number of nodes whose voltage deviation does not satisfy the requirements,and the extension of the duration.Finally,a quantitative evaluation model of the accessibility of distribution network to electric vehicles is established from two aspects of voltage deviation and static voltage safety and stability margin.Taking IEEE 33 node distribution network as an example,four different access modes of electric vehicles are defined,and the accessibility of distribution network to electric vehicles under different access modes is quantitatively evaluated.Taking a 10kV line of the actual distribution network as the object,the paper analyzes the acceptance capacity of the current power grid for electric vehicles,and verifies the effectiveness of the model and algorithm proposed in this paper.The research results show that the access mode of electric vehicle will have a great impact on the access ability of distribution network.The more the number of access nodes of electric vehicle,the lower the basic load,the stronger the access ability of distribution network to electric vehicle.