Study On Electric Vehicle Charging Piles To Network Considering The Constraint Of Power Quality

Due to the environmental pollution and the energy stress,the pollution-free pure electric vehicle is more and more popular in the domestic.At present,the electric vehicles are increasing rapidly in China.For meeting the charging demand of large number of electric vehicles and promoting the development of electric vehicles,charging facilities must be built simultaneously.As an important vehicle electric power supply facilities,the planning of the Charging pile is becoming focus of the social attention now.It is the most important question in the charging piles planning to determine the quantity of the charging piles under the condition of the standard of the power quality.In this paper,the model of the DC charging pile is built,the influence of the charging piles is studied and then the improved TLBO optimization algorithm is provided to determine the quantity of the charging piles.The main work is as follows:(1)The type of charging pile,the development of charging facilities and the related research status of charging piles are introduced in this paper.What's more,the standard of power quality is a significant factor in the planning.(2)The impact of the DC charging pile is the focus in this paper.Firstly,the structure of the rectifier and the high-frequency DC/DC converter with large influence which could impact the performance of the charging pile is analyzed.The working process of the VIENNA rectifier and the working state for different working mode of the phase-shifted full-bridge zero-voltage switch(ZVS)DC/DC converter is introduced.And then,the simulation model of VIENNA rectifier and phase-shifted full-bridge zero-voltage switch DC converter is built by Matlab/Simulink as simulation platform.Then the simulation results are given.The simulation result shows that the output of the mode can conform to the standard of the charging piles in the grid,and the mode can describe the process of the two stage of charging which contains constant current phase and constant voltage phase.(3)Based on the simulation model of DC charging pile,the influence of the number and location of the pile,the voltage of the access node on the voltage deviation,the power loss and the current harmonics of the grid are studied.And the principle of the influence process is analyzed at last.(4)An improved method of TLBO algorithm is proposed,and the result shows that the improved TLBO has a better search accuracy.In the reconstructed IEEE33 node distribution network test system,three nodes are selected as the access nodes of the charging pile.Taking the power quality index as the constraint conditions and the minimal grid loss as objective,the largest number of charging piles and capacity of different access node is determined by the TLBO optimization algorithm.According to the results,the optimization could improve the capacity of the charging pile and reduce the loss rate of the power grid.