Research On Control Strategy Of Active Power Filter Based On Improved Repetitive Control

With the use of a large number of power electronic equipment in my country's industrial production,it has brought unprecedented pressure on the governance of the power grid environment Active power filters can dynamically suppress harmonics and compensate reactive power,so they are favored in the field of harmonic management.The pros and cons of the active power filter control strategy seriously affect the final compensation effect.At present,the effect of conventional control strategies is not ideal,so this paper proposes a composite control strategy that improves repetitive control and quasi-PR control.The specific research contents of this article are as follows:(1)Analysis of source power filter and LCL filter.Firstly,the classification and basic working principle of APF are introduced.The three-phase three-wire parallel APF is determined as the research object of this article,and its topology,mathematical model and working principle are introduced in detail.Secondly,by introducing LCL filter on the AC side to suppress the high-frequency harmonics generated by the inverter,and its mathematical model,device parameter selection and stability were analyzed and introduced.(2)Current detection and modulation strategy analysis of active power filter.Firstly,the instantaneous reactive power theory is introduced.Secondly,the detection method based on the theory and the detection method are analyzed and compared.Because the latter detection is convenient and not prone to distortion,this paper chooses to use the detection method to detect the harmonics of the power grid and It was simulated and verified.The modulation method selects space voltage vector pulse width modulation,and its basic principles,reference voltage vector sector determination,voltage vector action time calculation and switching time calculation are elaborated and verified by simulation.(3)Improve the compound control strategy of repetitive control and quasi-PR control.Firstly,the APF double closed-loop control structure and internal model principle are introduced.The auxiliary compensator,internal model and compensator of the repetitive controller are improved,and related performance analysis is carried out,followed by the performance of the PR controller.An analysis was introduced.Aiming at the current inner loop,this paper proposes a compound control strategy to improve repetitive control and quasi-PR control,which will help to improve the problem of poor response speed of repetitive control and enhance the effect of APF compensation.(4)Simulation analysis of three-phase three-wire parallel active power filter.Using MATLAB/Simulink simulation software to build an overall simulation model,the power grid current waveform,current harmonic distortion rate,tracking command signal waveform and error waveform of PI controller and series composite control are compared and analyzed.The results The simulation effect of the series-type compound control strategy is ideal,with a harmonic distortion rate of 2.64%,good error characteristics and ideal tracking effect.Finally,the system response speed is simulated and verified by the method of sudden disturbance,and the effect is ideal.The improvement of the active power filter control link has greatly improved its harmonic suppression effect,promoted the improvement and optimization of the power grid environment and provided a reference for future work in the field of harmonic suppression.