基于准Z源逆变器的光伏并网控制策略研究

摘要

准Z源逆变器由于采用独特的阻抗网络,可利用桥臂直通实现升压,实现了与两级系统类似的功能.同时传统桥臂的死区设置被省去,可改善输出波形的质量,减小并网电流的谐波.基于单级准Z源逆变器的结构简单、可靠性高等优势,将这种新型逆变器应用于光伏发电系统,分析了准Z源逆变器的拓扑结构及工作原理,论述了基于三次谐波注入的升压控制,并对准Z源逆变器光伏并网控制系统进行设计,从而满足光伏并网的要求.通过仿真验证了系统结构和控制策略的有效性和正确性.%Because of the unique impedance network,a Quasi-Z-source inverter can realize a boost function by making the bridge arm shoot-though,similarly as that of a two stage system.At the same time,the dead zone set of a traditional bridge arm is omitted,which can improve the quality of output waveforms and reduce the harmonic of grid current.Based on the advantages of a Quasi-Z-source inverter,such as its simple structure,high reliability and so on,this new type inverter is applied to a photovoltaic power generation system.A topology structure and its operating principle are analyzed,the boost control based on three harmonic injections is explained,and the control of a photovoltaic grid-connected system based on a Quasi-Z-source inverter is designed for meeting the requirement of a photovoltaic grid-connection.The correctness and validity of the whole structural system and control strategy are verified through the simulation.