The Research On Power Quality Monitoring System Based On Virtual Instrument

In modern society, electrical energy has already become a kind of indispensable resources.However, with the increasingly complex power system load and new types of power electronicdevices widely used in the power system, The quality of power supply problem has also beenwidespread concern. So as to the problem of power quality, the power quality monitoring systemis studied in this article using virtual instrument technology developed recently.Firstly, five basic steady state indicators of power quality voltage deviation, gridharmonics, frequency deviation, voltage fluctuations and flicker, three-phase unbalance areanalyzed. On the base of that, the harmonics and frequency analysis algorithms based on IFFTand the flicker analysis algorithm are deep studied. Furthermore, curve fitting is used to correctthe deviation of attenuation characteristics of flicker analysis algorithm.Secondly, according to the demand of each index algorithm, a data acquisition module isdesigned this paper. The MCU C8051F020is taken as the control core of the DAQ module. Thevoltage and current signal in the power grid inputs into the AD of the MCU after taking theprocess of signal conversion, anti-aliasing filtering and amplification. The data after beingconversed will be transmitted to the software of the epistatic machine by USB, in order to beanalyzed. The method of combining NI-VISA and the D2XX Drivers is utilized in thedevelopment of the USB driver.Finally, a power quality monitoring platform is designed by utilizing the LabVIEW software.This platform can show various index results that being analyzed in the form of numbers orgraphics.In order to validate the correctness of the whole system, the function of each module isverified by taking use of the experiment that using the platform to monitoring the power qualityof low voltage power signal. What’s more, a simulation is made to analyze the deviation ofharmonic and frequency analysis. According to the data, the power quality monitoring systemdesigned fully meet the requirements of power supply quality assessment in the power system.