Study On Three-phase Active Power Filter With Dual-buck Circuit

With the development of power switch manufacturing technology, large-scaleapplication of power circuits has changed people’s life, followed by a significantproblem of the increase with grid current harmonic content. Nowadays, active powerfilter technology is an effective means to solve the problems of grid power quality.The system can track the grid harmonic with changing frequency and amplitude, andeffectively compensate. Among them, the shunt active power filter occupies themainstream in this field, and is the focus of academic research in various countries.In this paper, after carefully studying and analyzing the scientific literatures,research progress and development trend of active power filter are elaborated. Byanalyzing the shortcomings of traditional inverter circuit and studying dual-buckinverter circuit, dual-buck inverter circuit is proposed to be applied to three-phasethree-wire shunt active power filter. Because of no series switches in dual-buckinverter circuit, the legs are prevented to be straight effectively. Thus, dead circuitsare eliminated which are necessary used in conventional inverter circuit. For theharmonic detection algorithm, the relatively new FBD harmonic detection method isderived in detail. Comparing with it, the current common ip-iq harmonic currentdetection method is analyzed and derived in principle. Two methods are consistent inalgorithm thought. But FBD harmonic current detection has advantages like nomatrix transformation, simple structure and easy programming. For current controlalgorithm, triangular linear control is selected which is widely used in projects. Andalgorithm is optimized for the new main circuit structure. Based on those above,active power filter is designed by FBD method based on dual-buck inverter circuitThe ranges of main components are theoretically derivate and mathematicallycalculated in the system. Simulation software PSCAD/EMTDC in common powersystem is used to do simulation analysis. The simulation model of the system is set up. Under steady-state condition, the compensation cases with RL and RC linear loadare studied. Under dynamic-state condition, the compensation case with RL linearload is studied. The simulation results show the correctness of this system design. Onthis basis, a three-phase dual-buck active power filter hardware experiment platformis set up in this paper. Experimental results show that dual-buck active power filterbased on FBD detection method can effectively compensate grid harmonics. Powerquality is significantly improved after putting into use. The design achieves the statedgoal.