Study On Nonlinear Dynamic Characteristics And Stability Of Quasi-Z-source Photovoltaic Inverter

Focusing on the development of photovoltaic power generation is an important measure to promote low-carbon and green development,accelerate the construction of ecological civilization,and ensure that China achieves carbon peak by 2030 and carbon neutral by 2060.The important function of inverter is the transfer of energy.The inverter arm of the traditional inverter can not conduct directly,the boost effect is limited,and the resistance to electromagnetic interference noise is weak.In order to overcome many influences and deficiencies of traditional inverters,quasi-Z source photovoltaic inverters are selected as the research object in this paper.The quasi-Z-source photovoltaic inverter itself is a typical nonlinear dynamic system.During the actual operation of the inverter,due to the change of the circuit parameters of the quasi-Z-source photovoltaic inverter or the switching of the switch,there may be differences.nonlinear dynamics such as bifurcation and chaos.This not only affects the research,design,and development of aligned Z-source photovoltaic inverters,but also affects the stability of the inverters.Therefore,this paper takes the quasi-Z source photovoltaic inverter as the research object to study its nonlinear dynamic characteristics and stability.First,analyzing the background information and meaning of this thesis,and the research methods for nonlinear dynamics characteristics and stability of inverters are summarized,laying a solid theoretical foundation for subsequent research and analysis.Then,by analyzing the working principle of the quasi-Z source converter,the state equation of the system is derived,and the discrete model of the system is constructed.The nonlinear dynamics characteristics of quasi-Z source converters are compared and analyzed by numerical simulation with bifurcation diagram,maximum model eigenvalue trajectory of Jacobian matrix and poincare section.The Matlab/Simulink simulation model of quasi-Z source converter is built,which further verifies the accuracy of the analysis of nonlinear dynamics characteristics of quasi-Z source converter,and lays a solid foundation for the subsequent study of nonlinear dynamics characteristics and stability of quasi-Z source photovoltaic inverter.Secondly,taking the quasi-Z source photovoltaic inverter as the research object,the discrete mapping iterative model of quasi-Z source photovoltaic inverter is established by analyzing the working principle and state equation of quasi-Z source photovoltaic inverter.The bifurcation diagram,stroboscopic sampling diagram,stroboscopic sampling folding diagram and folded phase diagram of quasi-Z source photovoltaic inverter were obtained by numerical simulation.The nonlinear dynamics characteristics of bifurcation and chaos of the system were analyzed from multiple angles,and the parameter domain of the quasi-Z source photovoltaic inverter was obtained.The Matlab/ Simulink simulation model of quasi-Z-source photovoltaic inverter is built,which further verifies the accuracy of nonlinear dynamic characteristics and stability analysis of quasi-Z-source photovoltaic inverter in this paper.Finally,the experimental platform of quasi-Z source photovoltaic inverter is built,and the accuracy of theoretical analysis and simulation analysis of nonlinear dynamic characteristics and stability of quasi-Z source photovoltaic inverter is verified experimentally.