Research On Detection And Analysis Of Harmonics Based On Virtual Instrument Technology

With the wide application of power electronic devices, the harmonic problem isbecoming more and more serious. Industrial processes and people's daily lives areincreasingly affected by the harm of harmonics during to the harmonics problem. Sohow to solve the harmonic problem has became an urging demand. Harmonicdetection, as an important branch of harmonic problems, is getting more and morepeople's attention because of its keyposition in resolving harmonic problems.Currently the traditional harmonic detection equipments have the disadvantages ofvery few choices in function, poor scalability and high costs of the development andmaintenance. Virtual instrument technology has developed with instrumenttechnology and computer technology, whose essence is a virtual instrument systemwhich uses the computer as the hardware platformand designs functions depend onuser's requirements and realizes its measurement function through software. Theideology of Virtual instrument technology is "software is the instrument".Theemergence of virtual instrument changes the traditional concept of harmonicdetection,which is becoming an important direction of harmonic detection.This paper applies virtual instrument technology to harmonic detection to studyand develop a virtual harmonic detecting instrument based on virtual instrumenttechnology. Firstly, the concept and harm of harmonic are described, and then makedetailed analysis on the advantages and disadvantages of five current harmonicdetection theories. The fast Fourier transform is selected as the theory basis of thedesigning of virtual harmonic analyzer.The virtual harmonic analyzer has three functional modules: data collectionmodule, data processing module and the data storage module.The data collectionmodule can realize the offline and online transmission of external signals. Offlinetransmission can be realized by reading external files through Virtual Instrument andonline transmission can be realized by collecting data using AD7656 controlled byDSP2812. Data processing module can realize harmonic detection and spectralanalysis based on the fast Fourier transform with the help of powerful data analysiscapability provided by Labview; Data storage module can store analysis results asExcel files or image files for further analysis. The virtual harmonic analyzer designed in this paper can get accurate results withthe input of simulation signals and external signals collected bydata collectionmodule, which proves the rationality and Feasibilityof applying virtual instrumenttechnologyto harmonic detection.