Design And Research Of Three Phase Parallel Hybrid Active Power Filter

In recent years,the pollution problem of the nonlinear electrical equipment has become increasingly prominent,and harmonic control has become an important mission in the electric field.Shunt hybrid active power filter(HAPF)is one of the main ways to restrain the harmonic current of power system.This paper mainly explores the existing problems of parallel HAPF.Firstly,the key technical problems of parallel HAPF are expounded,and its operating mechanism and harmonic compensation characteristics are analyzed.And the stability of parallel HAPF is studied emphatically,the equivalent control block diagram of the parallel HAPF is deduced,and the resonance mechanism between the passive filter and the grid impedance is studied.In order to improve the stability of HAPF,a method to enhance the damping of the system is proposed.By adding a certain proportion of the harmonic components of the power grid voltage to the current command signal,the system resonance is suppressed.Secondly,as to the resonance problem of the LCL filter,the characteristics of several passive damping methods are analyzed.The active damping method of grid side inductor current feedback is mainly studied,and its physical model is established.As to the damping method of the feedback of the grid-side-inductor current through the high-pass filter,the mechanism of time delay in digital system is analyzed.The discrete domain model of the system is established,and the influence of the high-pass filter parameters is studied.Considering the influence of time delay,an optimization design method for high-pass filter parameters is proposed.Through the analysis of system root locus and zero poles,the stable interval of high-pass filter parameters is determined,and the active damping ring and digital current controller are optimized.Finally,the parameter design method of single tuned filter and active filter is introduced.And the simulation model of the system based on Matlab/Simulink platform is established,the simulations have verified that the parallel HAPF can achieve good harmonic compensation effects under various operating modes.At the same time,the simulation of the resonance of the parallel HAPF system is performed.The simulation results show the effectiveness of the proposed strategy.