Research On Power Quality Monitoring System Based On LabVIEW

In recent years, the power load characteristic has significant change. The influence,which causes by the nonlinearity, impact and asymmetry load, is not ignored for thepower quality. While, the sensitive consumers represented by IT and micro-electronicsindustry for the power quality, particularly, for the transient power quality, put forward themore strict requirement. To do well the management of power quality, is inseparable fromthe detailed and reliable first-hand data. At present, owing to lacking of the effective andcomprehensive power quality monitoring system, our country lags behind the developedcountries in power quality management. To study the power quality monitoring system,which is overall, effective and suitable for the experimental teaching, has importantsignificance. The traditional electric parameter test system is based on the hardware, itsfunction is single. So it is not convenient to be used in experiment teaching. In this paper,the whole power quality monitoring system is designed. Combining the idea of virtualinstrument, the development of power quality monitoring system is developed using theflexible data flow programming ability and abundant functions of LabVIEW. The systemcan simultaneously monitor five steady-state power quality indexes set by governmentstandard, the indexes include power grid harmonic, voltage deviation, frequency deviation,flicker and three-phase unbalance fluctuation.According to the actual requirement, this paper selects PXI4472data acquisitioncard in NI Company to finish the real-time collection of actual three-phase voltage. WithLabVIEW development environment as a platform, using data flow programming model,the power quality monitoring and analyzing system is estabilshed in PC to monitor anddisplay the wave and data. At the same time, the calculation and analysis of three-phasevoltage unbalance degree is completed. Because the actual power grid fault signal isdifficult to capture, meanwhile, considering the need of teaching experiment, this topicdesigned the power quality transient fault signals experimental platform basing on theLabVIEW, implemented three-phase electrical transient fault simulation analysis,provided the reliable power quality monitoring analysis results for the power sector.And established three phase voltage harmonics and waveform distortion monitoring and analysis system, completed the three phase voltage harmonics calculation using FFTimproved FAFT algorithm, designed the digital band-pass filter to realize the digtaldetection and analysis for three voltage fluctuation and flicker, so as to complete the testof three-phase voltage harmonics and waveform distortion.Finally in this paper, some indexes of power quality national standard (three-phasevoltage deviation, three-phase current allowable deviation, system frequency allowabledeviation) was analyzed, and the related indicators measurement method is studied, thekey parameters detection and analysis in power quality monitoring system was completedbasing on LabVIEW. While completing the actual three-phase voltage unbalance signalcalculation and analysis. Completed in the monitoring of real-time waveform displayinterface, monitor its operating status. For A, B, C phase voltage amplitude, phaseanalysis of the relationship. Comparison with national standards, complete power qualityassessment. And build a transient power quality fault simulation experiment platform, thisproject will expand the electrical tests applied to virtual instrument teaching experiment,make up the practical shortcomings of grid failure is difficult to capture. System canharmonic distortion, voltage fluctuations and flicker rate level is calculated to meet initialfunction of a single instrument to make up for domestic-related defects.