Research On Power Quality Control Of Ev Charging Station

With the development of social economy and China's attention to environmental protection has been increasing,New energy vehicles are attracting more and more attention as a clean and efficient way to travel.Electric vehicle charging is the key to the development of electric vehicle industry,and it has gradually become a research hotspot.As a typical nonlinear load,ev charging stations will inevitably affect the power quality of the power grid.This paper studies the power quality control strategy of ev charging stations to solve this problem.Firstly,introduced several circuits used in ev charger and common structures of ev charging stations.Several commonly used power quality control methods are analyzed and introduced.And Unified Power Quality Conditioner is selected for centralized control of power quality problems in ev charging stations and shortly introduced the UPQC.In order to systematically study the influence of ev charging stations on power quality of power grid,a simulation model of ev charging stations is built.Simulate the charging scenarios of single and multiple chargers with this model,summarizes the law of power quality problems in the operation of single or multiple charging machines,laying a foundation for the following studies on power quality control strategies and the establishment of overall simulation model.A unified power quality conditioner based on modular multi-level converter topology is designed for several possible influences of ev charging stations on power grid power quality.The main contents are as follows: Firstly,a new algorithm with fast response,high accuracy and simple programming was designed to improve the shortcomings of the existing compensation detection algorithm.Then designed the bottom modulation strategy of the converter.At last,designed a PI controller for converter to reduce output error.Designed part of the hardware circuit and software flow of the system.The hardware part mainly includes control system structure,converter level,LCL filter and so on,The software mainly includes the pre-charging strategy and the main program flow of the serial and parallel control board.The simulation model is built in Matlab/Simulink to verify the design,as the result shows,The UPQC designed in this paper has a good compensation effect,It is an ideal equipment to control the power quality of electric vehicle charging station.In the end of the paper,Summarized the unfinished work and prospected the futureresearch.