| With the rapid increase of electric power load, especially the increase of unbalanced, impact and nonlinear loads, the power quality problems have been more and more serious. On the other hand, more sensitive loads need higher power quality with the development of information technology.At present, our country power quality national standard was chiefly stipulated five quotas: frequency, harmonic and voltage deviation, three-phase unbalance and the voltage fluctuation and flicker. The objective of this paper is using the newest technology of the field of measurement and control now, the virtual instrument technique to which mentioned above five power quality standards. Its real time monitoring is able to go deep into analysis to the monitoring and then the influence. It also can provide the detailed power quality monitoring analysis and results for the power department.The virtual instrument is follow-on product outcome of software and hardware of computer technique, and it is replacing traditional electronic instrumentation step by step, and is the development direction of modern electrician's electronic measurement instrument. The virtual instrument technique is mainly used in measurement, control and emulation. Leading the virtual instrument technique to the power system possesses the most vast application foreground. LabVIEW of American Nation Instrument company development system is the outstanding representative of virtual instrument in the research and development at present. The key part of the technology of on-line monitoring and measurement of power quality in this paper is using LabVIEW and its compatible ADLINK's DAQ(Data Acquisition Card) to develop."The software is the instrument" is the major characteristic of virtual instrument technology. In this paper, LabVIEW graph software is adapted to realize a series of functions such as EFT, avoiding frequency spectrum leakage and interleaving etc that are realized by hardware realization originally. The hardware uses a personal computer based on PCI bus and a signal converter.The online power quality analyzer is designed and implemented in this paper. It is a new type of virtual instrument based on the advanced the DSP and computer technology. The analyzerhas the abilities of long-term online operating, real-time measuring and analyzing, managing of history data, etc. Compared with the traditional analyzer, it has many advantages, such as easy controlling, strong processing and graphics output, etc. It is able to record the abundant and integrated data for the Electric Department, and provide the reference for selecting correct compensation technology.In this paper, some key technologies are discussed and analyzed. The software function modules, such as data acquisition, data processing, data display, data saving, data playback and power quality reporting, are introduced. The crucial software design concepts of using multithread and Queue for exchanging data are emphasized.
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