Design Of Voltage Harmonic Monitor Based On Niosâ…¡

With the explosive development for the modern industry and national economy,harmonic problems of power system has become more and more serious.Harmoniccontent has become one of the most important influence indexes in power at home andabroad.Eliminating harmonic pollution and controling the harmonic content within thescope of the permition have been a unity of purpose between competent department andthe unit of electricity.So it is necessary to detect the harmonic accurately and timely.In the dissertation,there is a set of voltage harmonic detector has been designedwhich bases on the technology of Nios II soft nuclear processor and employs cycloneEP1C12as the primarily chip.Then,high-speed sampling conversion, calculation andanalysis with the support of Hilbert-Huang Transform(HHT),data storage,display andtransmitting of the single-phase voltage signal can be completed by the device.Thismonitoring system is composed by the following parts:the core board unit about FPGA(Field-Programmable Gate Array),the signal preprocessing unit,A/D samplingunit,Hilbert-Huang Transform computing unit,button control unit,display element andnetwork communication unit.In terms of hardware design,the total design scheme of the system has beengiven,the main chip and main module design,internal logic design of FPGA and PCBdesign in hardware circuit of the system are introduced in the thesis.In terms of software design,the design process of the main program controlmodule,the data acquisition module,algorithm modules about Hilbert-HuangTransform,buttons and display module,and communication module based onRS232,GPRS and ethernet network has been also discussed in this paper.The instrument can be used to measure the effective value of voltage and the vicevalue of2to25times voltage harmonic,each harmonic’s contains rate,total harmoniccontent,total harmonic aberrations rate and other parameters.And the same on,theseparameters can be displayed with the10digital tubes,and also can realize remotetransmission by a variety of communication with the help of the technologies aboutRS232,GPRS and ethernet.Finally,this method is provided to be feasible and right through comparisonbetween the measurement result and the actual value.