The Modeling And Nonlinear Behavior Analysis Of Power Electronics Multi-period Systems

Carbon peaking and carbon neutral require distributed power systems(massive wind farms and photovoltaic cells as power plants)with the high penetration rate of power electronic converters to generate the electrical energy and connect to power grids.Hence,power electronic converters are the core device of distributed power systems,and so its stability is associated with the safe operation of a whole power system.However,some important equipment,like cascaded DC-DC converters and inverters,has more than one running periods,such that the traditional discreite-mapping model cannot be used to analyze those systems.Thus the explanation and mechanism of their nonlinear behavior that has negative effects on the system cannot be provided.Therefore,this dissertation studies the modeling method of power electronics multi-period systems including cascaded DC-DC converters and inverters,and researches their nonlinear dynamics.The following works have been carried out:(1)First of all,according to the characteristics of cascaded DC-DC converters,inverters and rectifiers,the definition of power electronics multi-period system is proposed,and some typical examples are exhibited.Then,their difficulty of modeling and stability analysis is explained;(2)Secondly,for cascaded DC-DC converters,a simplifying modeling method is proposed,which can establish their accurate mathematical model considering the switching process.Meanwhile,the corresponding stability analysis methods are depicted,and a cascaded Boost converters system with peak-current controllers is taken as an example to show how to use this method.A hardware experimental platform is established to verify the correctness of theoretical analysis;(3)Thirdly,based a ground that some non-ideal factors,such as time delay,are considered,the state-space average model of a single phase full H-bridge inverter is built.Bode diagram and poles analysis are applied to study its stability analysis.A hardware experimental platform is established to verify the correctness of theoretical analysis;(4)Finally,the state-space average model and Filippov method are employed to study the stability of a double-loop PI control full H-bridge inverter.The mechanism and sources of its slow-scale instability and fast-scale instability are discussed.The passive damping method and sine wave compensation technique are exploited to the inverter to suppress its Hopf bifurcation and period-doubling bifurcation.A hardware experimental platform is established to verify the correctness of theoretical analysis;...