SYSTEM AND METHOD FOR MEASURING HARMONIC DISTORTION RATIO IN WATT-HOUR METER

摘要

The present invention relates to a watt-hour meter measuring system for harmonic distortion and a method thereof. The watt-hour meter measuring system for harmonic distortion according to the present invention comprises a step of producing the fundamental frequency (fo) from a voltage signal of the target of the harmonic distortion, a step of generating a sine and a cosine signal by using the calculated fundamental frequency (fo) respectively, a step of calculating the number of each component by using the correlation between the voltage signals of the generated sine and cosine signals, a step of generating a fundamental frequency sinusoidal signal based on the calculated numbers of each component, a step of detecting the harmonic signal from the difference between the voltage signal and the fundamental frequency sinusoidal signal, and a step of calculating Total Harmonic Distortion (THD) by using the harmonic signal and the voltage signal. According to the present invention, the target voltage signal can be separated into the harmonic signal and the fundamental frequency signal to obtain harmonic distortion (THD) which can overcome the disadvantages of the error performance of Fast Fourier Transform (FFT) method, and it can enhance the speed of the calculation since the complex calculation of FTT will not be processed.;COPYRIGHT KIPO 2014; [Reference numerals] (AA) Start; (BB) End; (S201) Detecting fundamental frequency(fo) from voltage signals among Total Harmonic Distortions (THD); (S202) Minimizing leak frequency of voltage signals by windowing; (S203) Generating sine and cosine signales by using detected fo; (S204) Calculating size of each component by using correlation of generated sine and cosine signals; (S205) Generating fundamental frequency sinusoidal signals based on each size of component; (S206) Detecting other harmonic signals from difference between volatge signals and sinusoidal signals; (S207) Calculating THD by using harmonic signals and voltage signals