The Power Quality Monitoring System Based On Virtual Instrument

With the economic development, industrial and living power equipment is more andmore multifarious. Electricity consumption is more and more big which caused a series ofpower quality problems. High power quality has become an object of power sector andpower users. To ensure the plant’s production efficiency and the safe use of electricalappliances, power quality required to ensure certain standards. Energy parameters formonitoring results can be used as a basis for measures to be taken. When problems arise, todetermine who is responsible. So power quality monitoring is very meaningful.This paper first studied the power quality monitoring devices at home and abroad, andexplains the lack of conventional devices. Recalling virtual instrument development processand pointed out some of the advantages of virtual instrument. Studied the meaning of eachparameter of electric power and several main parameters of power quality does not accordwith a standard may lead to harm.System formed the signal acquisition module, mainly including: transformer module,signal adjusting circuit, A/D conversion circuit, protection circuit and single-chipmicrocomputer sampling circuit. Use the virtual instrument NISA module to establishcommunication with the microcontroller, and use C code in single chip microcomputercommunication program. Finally virtual instrument and SCM systems can communicate, sothat the signal can be collected.Studied power quality fluctuation and the harmonic value measurement in the processof signal processing problems and algorithms. And Analyzed the method of FFT and IECrecommended flicker measurement method. To set up mathematical model in the virtualinstrument provides a theoretical basis. At the same time, to study the other indicators ofmathematical algorithm, finally established including voltage, current, frequency, power,imbalance, harmonic and flicker mathematical model and the corresponding virtualinstrument program.Finally, the paper studied that the IEC recommended measuring method is notsensitive to high frequency harmonics. An improved method is proposed, which makesflicker measurements can get accurate value when the signal contains higher harmonic, someasurement system is further perfect.