Research On Control Stystem Of Active Power Filter

With the rapid development of the power electronics,more and more nonlinear electronic equipments have been used in power system.The harmonic of voltage and current brought from these equipments have affected the quality of power.The active power filters is a new harmonic and reactive power compensation equipment. Compared with the traditional L-C filters,the active power filters have the merits in rapid reflect,better compensation and the ability in dynamic compensation.In this paper the components of the active power filters are introduced,which mainly contains harmonic current detecting and tracking control of current.The p,q,i_p,i_q and an improved harmonic current detection methods based on the instantaneous reactive power theory have been analyzed.Several strategies of current tracking control are used in shunt active power filters such as triangular carrier control and hysteresis loop current control have been researched,and the characters of them have been gained through theoretical analysis.A linear feedback approach based on inverse system method is presented in this paper.Aiming at the nonlinear identity of the mathematic model of the active power filter in d-q synchronous reference frame,a pseudo-linear model is given based on the inverse system method.A linear quadratic controller is designed to meet some performance index in terms of the pseudo-linear system.Then the active power balance among voltage-source APF(Active Power Filter),source and nonlinear load is analyzed.Based on this analysis a direct source current control strategy of shunt APF based on inverse system method is presented.Then the tache of harmonic current detection is omitted.In this control scheme,source reference current is obtained applying the PI regulator to the instantaneous difference between the reference DC-link voltage and the actual DC-link voltage.On the basis of theoretical analysis and simulated research,the shunt active power filter based on TMS320F2812 has been designed,meanwhile the software and hardware have been introduced in detail.Initial lab research on the shunt active power filter has been done.