Reserch Of Dower Quality Monitoring System Based On Ethernet

As more and more non-linear electrical equipment have been used, thePower Quality in modern power system have to face serious threaten. To dealwith this threaten, people carry out a useful method which is building a powerfulSmart Grid. One of the key to Smart Grid is to build a powerful power qualitymonitoring system. A powerful power quality monitoring system dose not onlyneed the accuracy of measurement, but also need the reliability and real-time ofcommunication.This paper introduces the standard of Power Quality on the basing on theanalysis of current research in the world. Give the method of computing basicpower parameter which include frequency, value, power parameters; giving thecalculation of voltage deviation, frequency deviation, three-phase unbalance, thenfocus on researching the methods of voltage flicker demodulation. Demodulatingvoltage flicker using energy operator is researched and improved, based onanalysising and researching of several basic methods of voltage flickerdemodulation, such as by using square, by using full-wave recetifier, by usingRMS, by using wavelet transform, by using Hilbert transform. The energyoperator algorithm is applied to voltage flicker measurement feasibility, which isvertified by the simulation software of MATLAB in amplitude flicker signal ofsingal-frequency and multi-frequency and compared with the result of Hilberttransform method and square detection method. Based on introducing the methodof calculating the flicker severity used by the IEC recommended flicker meter,the method based on FFT to calculate the flicker severity is given.The power quality monitoring system based on Ethernet is designed. UsingTMS320F2812as the core of hardware circuit of lower position machine. Itsmine use is to sample and process the signal in the Grid; the processed data isused to compute basic electrical parameters and Power Quality parameters; then communicate with upper computer. The physics layer of the Ethernet’s agreementis realized by ENC28J60. The mine use of upper computer is to the datacomputed by Lower position machine.According to modular programming ideas, the DSP software are designed toachieve the data sampling, electrical parameters metering, demand metering,power quality monitoring, event logging and communicating functions. Thesoftware of the upper computer has been designed and the joint commissioning ofthe communication function with the lower position machine has been carried out.It turned out that it’s reliable and meet the requirement of real time nicely.