Modeling And Control Strategy Of Double PWM Converter For Doubly Fed Induction Generator

Energy is an important material basis for the survival and development of human civilization.The development and progress of human civilization society can not be separated from the emergence of high-quality energy and the use of advanced energy technology.As a clean renewable energy,the utilization of wind energy can effectively solve the above problems.In the past twenty years,the control of doubly fed induction generator(DFIG)has been greatly improved with the development of control theory.However,Considering the complex structure,incomplete information and strong nonlinearity in some parts of DFIG system and the state of power grid is sometimes unstable so that the DFIG control strategy is required to withstand the power grid fault.Therefore,the research of modeling and control strategy of dual PWM converter in DFIG is of great significance.In this paper,the DFIG power generation system is taken as the research object.Research on linear identification modeling and DFIG control strategy of dual PWM converter is emphasized.Firstly,the operation principle and characteristics of the back-to-back dual PWM converter are introduced in this paper.After that,an approximate linear mathematical model of SVPWM link in dual PWM converter is established by using hybrid modeling method.The structure of the model is determined by mechanism analysis method,and the specific parameters of the model are obtained by experimental method.At the same time,based on the LabVIEW simulation platform,the simulation model of double PWM converter is obtained.Then,based on the research on the control strategy of the DFIG's power grid side converter(PGSC)and the DFIG's generator rotor side converter(GRSC)under ideal grid voltage conditions,the principle of unbalanced power grid and its influence on the operation of DFIG power generation system are analyzed.The principle of unbalanced power grid and its influence on the operation of DFIG power generation system are analyzed.Then the control strategy is further improved:the structure and characteristics of the resonant link are studied,and an auxiliary proportional resonant controller and an active proportional integral resonant controller are constructed by using the resonant link.Based on these two controllers,the improved control strategy of PGSC and GRSC is established in the case of unbalanced power grid.In order to facilitate the use of the above control strategy,a set of engineering parameters setting method is given.Finally,based on the software simulation platform of LabVIEW,the simulation model of 1.5MW DFIG power generation system model is built.The traditional vector control strategy and the vector control strategy based on the resonant controller are compared and analyzed by using the simulation model.It is proved that the vector control strategy based on the resonant controller is feasible and effective in the case of imbalance.