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High quality of electric energy has the vital significance for national economic development and production and life, the worsening power quality problem has already become the power sector and power users widely concerned problems. Therefore, we need to monitor and analyze power quality parameters at real-time, assess the quality of power quality and find out the cause of power quality deterioration, provide basic support on researching effective measures to improve the quality of power for the power sector.Traditional power quality monitoring instrument has single function, complicated structure, and high cost, current monitoring methods and form has many problems, already no longer adapt to the current increasingly complex requirements of power quality monitoring. With the steady progress of computer technology, communication, measuring and control technique, virtual instrument technical which produced in 1986 gradually developed. LabVIEW graphical software has some advantages of high-performance, strong extensibility, short development time, simple hardware structure. It’s widely used in the engineering industry measuring and control areas, greatly shortens the product development cycles, improve the efficiency.Therefore this paper uses virtual instrument benefits to development electrical energy monitoring and analysis system. The system can monitor main electric energy parameters including voltage, current, frequency, phase, power, harmonic and three-phase voltage unbalance,and can also provide certain analysis function . Its characteristic is simple structure hardware, low cost and rich function, greatly offset the disadvantages of traditional monitoring instruments and monitoring methods.This paper firstly studies the basic problem of power quality monitoring, including the necessity of power quality parameters monitoring, the shortcomings of traditional power quality monitoring theory and method, the superiority and feasibility to make use of virtual instruments to monitor power quality. It mainly studies the mathematical model and digital processing of monitoring voltage deviation, frequency deviation, three-phase voltage unbalance and harmonics as focus. Harmonic analysis adopted fast Fourier transform method. Formulate the hardware and software design, emphasis on research system individual functional modules development with LabVIEW software. The software is tested at the same time.Finally it summarizes the research and insufficiencies, and makes prospect of the power quality monitoring development direction in the future.
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