Research On Power Harnomic Monitor Device And The Communication Technology

In recent years, because of rapid growth of power and electronic device,harmonic pollution in electricity grid system becomes more and more serious.It can produce harmful affect to all kinds of power device, communicationequipment and wiring, even generate accident of power system so that directlyeffect safety production and normal running of lives. In addition, due tothe improvement of industrial automation, such parts of an apparatus as MPUand PLC are applied to industrial process controls, which are disturbedeasily by stirs from power system. Therefore modern industry needs higherpower quality than old one does. As a consequenceto monitor and study powernetwork is not only a premise to confine and eliminate harmonic but also aurgently demand to assure power supply system to run safely and economicallyand devices and personal safety.This paper presents a new design of a harmonic test apparatus for powersystem after read lots of information of this area. The apparatus is makeuse of the techniques of digital signal processing, and based on thetechniques of DSP andARM. The apparatus on the spot performs mathematicsand numerical processing including FFTand so on tovoltage and current signand transfers data to PC. By the advanced network interface technology ofARM, this device is an embeddedsystem by which the network interface based on the TCP/IP agreement and the RS232C interface based on the modem totransfer the data to PC. Besides, the paper introduces that the Power QualityData Inter-change Format (PQDIF) which is recommended by StandardCoordinating Committee 22 (SC22) on Power Quality and IEEE 1159 Working Groupon Power Quality Monitoring. It offers a solution to the problem of differentpower quality file formats. The paper are laid on the following:(1) overallplan design and hardware introduction of system, (2)Design of hardwareincluding circuit and principle of the examination electric circuit of theelectric voltage electric current, A/D conversion, phase lock, thecommunication module of ARM, liquid crystal display and keystroke and soon,(3) D Design of system software including digital filtering, FFT, A/Dconversion and monitor interface of PC and so on, (4)make detailed analysisto the structure and merit of Power Quality Data Interchange Format (PQDIF).