Research On Three-levelactive Power Filter Based On Space Vector PWM Control

In recent years, with the rapid development of power electronic technology, more andmore nonlinear load is used in the power system, so the harmonic problems which arebrought by power electronic devices become more and more serious. In order to improvethe power quality of the user side, active power filter (APF) is born at the right moment.This paper choose three-level active power filter based on space vector PWM control as theresearch object. The theory of APF is studied, and a new kind of track control method onthe compensation performance is emphatically analyzed. The system of three-level APFbased on SVPWM control is set up on Matlab/Simulink platform which can verify thecorrectness of the system.In this paper, the detection part of the harmonic current is based on instantaneousreactive power theory, the detection principle of p、q operation way and ip、iqoperation wayare mainly studied.When the voltage in power grid distorts, p、q operation mode will appearerror, but ip、iqoperation mode is not affected by voltage distortion，so in building thesimulation, ip、iqoperation way is used at the current detection module in this paper.In harmonic current tracking control, this article compares the advantages anddisadvantages of all kinds of multilevel topology structure and choose diode-clamped typeas the main body of the inverter. First, this paper introduce diode-clamped type three-levelinverter working-state conversion process, then bring the principle of space voltage vectorinto the three-level structure and draw the space vector map under three-level structure.Therelationship between space vector and inverter switch state is studied, which furtherdetermines the position、the action time and the arrangement of the order of the switchvector in the space vector control, and forms a complete three-level space vector controlmethod. This paper also focuses on the DC voltage control method of three-level activefilter, and analyzes the impact of some switch state to the midpoint voltage fluctuation.With no impact to the compensation effect, some redundancy switch states which have anadverse effect upon midpoint voltage are abandoned to maintain the stability of the DC sidevoltage.Finally, based on Simulink platform, the three-level active power filter based on spacevector control is simulated. Simulation results show that the method has a goodcompensation effect which verify the effectiveness of the proposed control method.