The Research Of Portable Power Quality Analyzer Based On Dual CPU And Embedded Linux

With the rapid development of China’s national economy and strong&smart griddepth construction, a great number of electrical equipments which adopt new technologiesare used in industrial production and daily life, it makes the modern grid electricity loadconstitute undergone tremendous changes. On the one hand, the new electrical equipmentswhich sensitive to electromagnetic interference require better power quality; On the otherhand, the universal application of a large number of non-linear and the impact load lead tothe utility grid harmonic pollution and the decline of the power quality, causing a variety ofpower quality problems. With the increasing emphasis on power quality of the electricitymarket, also proposed higher requirements for power quality detection means. Therefore,researching and designing a high-performance power quality analyzer has a very importantpractical significance.This paper designed a portable power quality analyzer which based on dual CPU andembedded Linux. The hardware circuit design and software programming ideas of analyzerwas introduced in detail. The analyzer is consist of the underlying DSP data processingplatform and the upper ARM11control management platform. The DSP data processingplatform using hardware phase-lock frequency multiplication technology, to realize thewhole cycle synchronous AC sampling of the grid AC signal which after conditioning. Thesoftware algorithms used windowed FFT algorithm to reduce spectral leakage and fenceeffect. The ARM11control management platform worked with embedded Linux operatingsystem to achieve the good interactive interface, instrument configuration and networkcommunication of analyzer. The dual CPU communicated with each other via the SPI bus.This design not only could detect the basic electrical parameters of the utility grid, such asthree-phase voltage RMS, three-phase current RMS, active power, reactive power,apparent power, power factor, but also could detect power quality indicators which arespecified in GB, such as voltage deviation, frequency deviation, three-phase unbalance,power grid harmonics, voltage fluctuations and flicker, the analyzer also has Ethernetcommunication function.The paper first introduced the research background and research significance of thesubject, by comparing the commonly used power quality analysis algorithms, proposed thepower quality index calculation method that based on the windowed FFT algorithm andanalyzed the problems that need attention when the FFT algorithm practical used. Thenusing the modular design concept designed the hardware and software system of theanalyzer. The hardware design includes signal conditioning module design, frequencytracking module design, the A/D data acquisition module design, DSP data processingmodule design and ARM11control management module design. The Software designincludes DSP main program design, the frequency measurement program design, A/D analog-to-digital conversion control program design, windowed FFT data processingprogram design, the SPI communication program design, embedded Linux softwaredevelopment environment build, S3C6410’s SPI devices add under Linux&itscommunications program design and analyzer interactive interface design. Finally, thehardware and software anti-jamming design was introduced, the analyzer was tested andthe error analysis was given. The test results show that the analyzer can meet the testingrequirements of power quality indicators and has a good prospect.