Research Of ARM-based Detection Device For Power Quarity

Nowadays, more nonlinear large loads were used, so that the quality of power systemdecline with each passing day.Although the electric locomotive and rectifying device improvethe technical and economic, but the harmonic also greatly increases in power system. Inaddition to quality problems of the power harmonic, other quality problem of power has alsobrought negative effect. Such as the abnormal deviation of voltage and frequency will makethe big deviation between power, rotational speed of asynchronous motor and the normalvalue, and make the efficiency of the production machinery is reduced and the quality of theproduct is influenced. Therefore, in order to improvement of power quality, power quality inpower system must be detected, evaluated and analyzed. According to the currentdevelopment and requirement of power quality detection devices, this paper studied anddesigned a kind of power quality detection device, which has the function of underlying dataacquisition, data calculation, local storage, local real-time display and ethernetcommunication. The device has the advantages of high speed, high efficiency, real time andnetwork transmission and other characteristics, and has the advantages of small volume, lowpower consumption, cheap cost.Referring to the large numbers of related literatures and national standards of powerquality, a FFT harmonic analysis method was researched. The work in this paper is dividedinto the following major parts:(1) In this paper, the spectrum characteristic of Nuttall self-convolution window wasanalysed, the principle and application of phase difference correcting method of discretespectrum was researched. And combining with the design requirements, phase difference FFTharmonic analysis based on Nuttall self-convolution window was researched. The algorithmwas simulated utilizing MATLAB to validate the correctness and precision of the algorithm.(2) According to the function requirement of the power quality detection device, thehardware circuit was designed and realized. Firstly, the circuit of data acquisition modulebased on the16bit,6channels simultaneous sampling ADS8364was designed andproducted.Secondly, the local SD storage, liquid crystal display, ethernet communication andselecting circuit of peripheral chip were designed and realized.(3) According to the requirements of the system, the software system which takes uC/OS-II as real-time operating system was designed and realized.The uC/OS-II operatingsystem was transplanted, and the modules of data collection, FFT analysis, SD storage, liquidcrystal display and ethernet communication were compiled.(4) The error and anti-interference of detecting system were analysed, And throughexperiments the detection device was tested.