Three-phase Current Harmonic Detection Applied To The Active Power Filter

Due to the rapid development of power electronics technology, a variety ofpower electronic devices are widely applied to power system, industry,transportation and family. At the same time harmonic hazards are becoming moreand more serious and they are considered as major hazards to the grid. Ifuncontrolled, they will affect secure and economic operation of the entire powergrid.Active power filter (APF) is a major device for dynamic compensation ofharmonics in power system, the basic princi_ple of compensation is to detectharmonic current from the compensation object and then to generate compensationcurrent which has equal size to the harmonic current and opposite direction by thecompensation device so that the harmonic current in the system is offset. Therefore,accurate and real-time detection of harmonic content in the grid has very importantsignificance to prevent harmonic hazards and ensure secure operation of the grid.The basic concepts of harmonic, harmonic generation and harmonic hazardsare introduced in this paper. The development, classification and topology of activepower filter lay a theoretical foundation for analysis of harmonics and designationof active filters. A three-phase detection method based on single-phase harmonicdetection is proposed by studying three-phase harmonic current detection andanalyzing several common harmonic detection algorithms. Because of theengineering application, a more mature i_p-i_q algorithm is adopted to carry outexperiment of which TI’s TMS320F2812chi_p is selected. The hardware andsoftware designation of the experimental platform as well as selection anddesignation of the low-pass filter is analyzed in detail. Experimental results areidentical to simulation results and the reliability of the detection algorithm and theexperimental platform is proved.