Active Disturbance Rejection Control Of Quasi-Z Source Inverter Of Photovoltaic Grid-connected System

With the increasing depletion of fossil energy,solar energy,as a new type of clean energy,will be one of the main energy sources that mankind depends on in the future,and photovoltaic power generation is an important way to effectively use solar energy.In the photovoltaic system,the inverter plays an important role in connecting the photovoltaic array to the grid,and its comprehensive performance and economic cost are factors that need to be considered.This paper takes the quasi-Z-source inverter system as the research object.Aiming at the shortcomings of the existing control strategies,a control strategy that applies the active disturbance rejection control technology to the photovoltaic control system is proposed,thereby reducing the total harmonics of the grid-connected current.The wave distortion rate also improves the grid-connected power quality of the photovoltaic system.The main work content of this article can be summarized into the following aspects.(1)The overall design and research of photovoltaic grid-connected system based on quasi-Z-source inverter.Through the research and analysis of the two working states of direct and non-direct Z source network,its working principle is introduced,and its mathematical model is established,and the established quasi-Z source inverter is stabilized by building a MATLAB/Simulink model.Sexual analysis.Then analyze the working principle of the LCL filter and establish a mathematical model,and build a simulation model to analyze its characteristics.Finally,a unified mathematical model is established for the entire photovoltaic system,which provides a theoretical basis for the subsequent controller design,and calculates and selects the parameters of the system’s quasi-Z source network and LCL filter.(2)Research and analyze the overall control strategy of the system.It mainly includes two aspects: inner loop control and outer loop control.Aiming at the problems of dynamic response characteristics and unsatisfactory anti-interference performance of the existing grid-connected inverter control strategy,this paper adopts auto disturbance rejection control as the control strategy of the system to improve it,and analyzes the principle of the auto disturbance rejection control technology.And the establishment of the model,its stability was analyzed.According to the mathematical model and characteristics of the quasi-Z source inverter,the auto-disturbance rejection control strategy is adopted in the voltage outer loop,and PI control is still used in the current inner loop,so as to establish the controller of the quasi-Z source inverter system.(3)Through the MATLAB/Simulink platform,a simulation model of the photovoltaic system is built,and the control strategy of the designed photovoltaic system is simulated and verified.And through comparative analysis,the superiority of active disturbance rejection control is verified.