Study On Chaos And Controlling Chaos In Two-stage Photovoltaic Grid Connected Inverter

Solar power is the result of converting sunlight into electricity.Sunlight can be converted directly into electricity using photovoltaics(PV),and it is an important form of rational utilization of solar energy.As the most promising "future energy",solar photovoltaic technology has become the focus of national research,Photovoltaic grid-connected inverter(PVGCI)is an important component of the entire energy-loading system and its stability is particularly important.Therefore,it is very important to study the chaotic behavior of the grid-connected inverter and propose a targeted chaotic protection control strategy,which is very important for the safe and stable operation of the power grid.In this paper,the bifurcation and chaos phenomenon in the two-stage photovoltaic inverter system is analyzed and studied.The concrete work is summarized as follows:First,the background and significance of this research is analyzed,the present situation of chaos control and chaos control of power electronic converter is reviewed,and then the significance of this research is pointed out.The research objectives and content of this subject are determined.Second,based on the research of the main circuit topology structure of PVGCI.the state equation of PVGCI is constructed based on KVL and KCL.Chaos and controlling chaos in PVGCI is studied.The critical parameters,with which chaos are induced in the PVGCI,are investigated by analytical methodsThird,as the two-stage photovoltaic grid-connected inverter state equation parameters are more complex structure of this feature,we designed a chaotic controller based on improved state correlation theory to realize chaotic control of two-stage photovoltaic grid-connected inverter.The control strategy only changes the state variable correlation coefficient,the method has the advantage of less control,the design is simple and easy to implement.Fourth,the controller are designed based on state feedback and parameter perturbation,by adding state feedback to the relevant state variables,the control of PVGCI chaotic behavior is realized.At the same time,it can make the grid connected current and the voltage frequency phase of the public network to achieve synchronization.Because the control strategy belongs to the closed-loop control,it has good robustness in the process of controlling the system.It is necessary to set the desired control objectives in advance.Fifth,based on LaSalle invariant theory,an adaptive law of controlling chaos is presented in this paper,which enables avoiding the influence of undeterministic equilibrium of system.The desired effect of system control can be achieved.Finally,the whole thesis is naturally concluded with the future work clarified.