Research On The Control Scheme For The Three-Phase Four-Wire Tri-Level APFs Without Harmonic Detection

With the massive investment in non-linear load applications, we concern aboutharmonics governance issues in three-phase four-wire distribution power system.As thethree-phase four-wire three-level active filter can effectively filter out the currentcomponent of load harmonic, so this paper focuses on three-wire four-wire APF systemwith three-level Bridge,this paper mainly research the following aspects.This paper derived three-phase four-wire APF the average linear mathematical modeland mathematical mode.in the stationary coordinate system converter which APF isexpressed as equivalent controlled voltage source and a controlled current source,This paper analyzes the energy transmission process between APF DC side and ACside and obtained this conclusion that APF can obtain the reference current through theadjustable capacitor voltage.Such a study proposed a theoretical basis for the control withnon-harmonic detection.I also research on non-traditional APF power and active control ofthe system model and found the adverse effects with harmonic detection of the system, so Iindirectly obtained the conclusions that the system don’t need to harmonic detection.This paper analyzes double-closed-loop controlled system architecture of the APFbased on harmonic detection, and through the improvement of the original system derivedcontrolled structure, I proposed a new type of double-closed-loop control strategy withnon-harmonic detection.This paper found a way of control with repeative control and P control in currenttedloop,and analyze each parameter of the repetitive controller,and according to three-phasefour-wire three-level Bridge carved arm-type capacitor structure, I designed the controllerwith the mathematical analysis and related basis.This paper has set up a simulation map, with the three-phase non-linear unbalancedload and three-phase nonlinear balanced load,at the same time,I improved the experimentaldevice ofthree-phase-four-wire-three-level-Bridge carved arm-type capacitor, done anexperiment with three-phase nonlinear unbalanced load to test the proposed theory andcontrolled method.