Research On Three Phase Three Wire Active Power Filter Based On Repeated Control

The research object of power electronics technology is fast and controllable power conversion,which is characterized by convenience,economy and safety,and improves human's efficiency in production and life.However,with the wide application of nonlinear and time-varying load power electronic devices,the negative effects become increasingly obvious.The switching action of the power electronic device injects a large amount of harmonic components into the power grid,resulting in serious distortion of the voltage and current waveforms in the power grid.The operation of power electronic equipment caused severe harmonics in the power grid.Active filters can effectively control harmonic pollution.The application prospect is very broad.This paper first introduces the related knowledge of harmonics and its adverse effects.After comparing the existing methods of harmonic control,the advantages and theoretical basis of active power filters are described.Secondly,the mathematical model of parallel three-phase three-wire active power filter is established.On this basis,this paper introduces the technology of harmonic command extraction and the generation of compensation current.Active power filter control effect of a direct impact on the compensation performance.The current loop controller is designed in d-q coordinate system by mathematical modeling of active power filter system.Aiming at the shortcomings of repetitive control in current loop control,which has a fundamental period delay,the fuzzy PI controller with better dynamic response is used in combination with it to study the compound controller in series and in parallel respectively.In the composite controller,the PI controller is used to improve the dynamic response of the system.The fuzzy control real-time adaptively adjusts the PI parameters on-line.The repetitive control is used to improve the steady-state compensation accuracy of the system.The detailed design of the two kinds of compound controllers process.Finally,the parallel three-phase three-wire active power filter is modeled and simulated in Matlab/simulink.The simulation results show that the parallel three-phase three-wire active power filter with good harmonic compensation accuracy and fast dynamic response.