Study On The Effect Of Harmonic On The Electrical Energy Measurement Of Watt-hour Meters

With the broad application of the electrical and electronic technology in the industry branches and the power apparatuses, the number of non-linear loads is much more and more, and the capacity of them is biggish, so a mass of harmonic is injected into the power system, which produces the waves of voltage and current in power system to be aberrant seriously. Because most of apparatuses and meters are designed according to the 50Hz sinusoidal wave, the showing data are not precise. Electrical energy measurement is the gist of the economic accounting in power system, and the measuring precision affects the economic and society benefit between provider and asker. To insure the veracity of electrical energy measurement is important specially. The watt-hour meters are the core part and the basic measure, whose measuring veracity count for much the precision of the electrical energy measurement, so it is necessary to study thoroughly on the effect of harmonics on the electrical energy measurement of watt-hour meters.By analyzing the structure and working principle of induction watt-hour meter, this paper proposes one non-linear ameliorated mathematic model to study its electrical energy measurement error; By analyzing the structure and working principle of electronic and its time-division-multiplier, this paper founds one simulation model for the first time; Through the calculating analysis and simulation analysis, this paper studies roundly and thoroughly the effect factors and effect degree of the meters under the harmonic; At last, the measurement standard and measurement mode are discussed primarily.The analysis results show that: the frequency characteristic curve assumes the downtrend, so the electrical energy measurement of the induction meter will produce biggish error when the content of the harmonic is big, no matter taking the whole energy as measurement standard or basic wave energy. Compared with the induction meter, the electronic meter's measurement error is affected diminutively by the change of the frequency, that is to say, the electronic meter has a wide frequency respond characteristic and its error-frequency characteristic curve is flat. Therefore, taking the whole energy as measurement standard, the measurement error of electronic meter is less than that of induction meter very much; while the measurement error of electronic meter is bigger than that of induction meter when taking the basic energy as measurement standard. Different measurement standard produce the estimate for the meter's measurement error. The theoretic analysis shows that the non-linear load is harmonic source, and the harmonic produced by it is transformed by part of basic wave absorbed by it from power system, therefore, traditional measurement mode has someimpertinency. One new measurement mode is proposed to be discussed by all.