Research On Grid-connected Control Strategy Of Energy Storage Type Quasi-Z Source Photovoltaic Inverter

The problem of energy depletion is becoming more and more serious,and how to use photovoltaic energy has become a hot research issue.The improvement of photovoltaic power generation efficiency and grid-connected stability has a great significance for the development of the photovoltaic industry at this stage.The paper takes the quasi-Z-source grid-connected inverter as the research object to study in-depth on the power generation efficiency and grid-connected stability.First of all,this article analyzes different inverter topologies,it has theoretical support for us to choose quasi-Z-source inverter.Because of the poor grid-connected stability of traditional quasi-Z-source inverters,we use the energy storage module to the topology and analyze the working principle and function.It’s different from ordinary inverter that we should use an improved ways of SVPWM.Then I have to analyze the four debugging methods about SVPWM to choose the best debugging method for my test.Secondly,given these two issues of speed and accuracy in MPPT algorithms,I propose an algorithm to speed up operation and reduce fluctuations by new fuzzy rules,PI and disturbance controller.It greatly improved the deficiency of power generation.Based on the modulation of ZSVM-six,I added feedforward compensation and quasi-proportional resonance to the two-phase stationary coordinate system.Then I designed a control method for the energy storage of the quasi-Z-source inverter,and also designed a control method for grid connection that based on VSG control technology.Used the control technology of VSG to control the output power,the accumulator could supplement the lack to power automatically.This simulation proves that this control method can respond quickly when the grid frequency is abnormal and can adjust the frequency change of the grid at the same time.Finally,I built a complete system on the platform based on the designed modulation method and many kinds of improved control methods.The full text compared the quasi-Z-source inverter system,the quasi-Z-source inverter system of energy storage and the quasi-Z-source inverter system of energy storage based on VSG control technology.The paper designed a prototype based on them.The results of simulation and physical testing show that these kinds of ways for grid control can improve the efficiency of power generation and improve the stability of grid connection.So that the article can achieve the expected purpose by studying the quasi-Z-source inverter system of energy storage controlled by VSG control technology.