An Approach for Electrical Harmonic Analysis Based on Nuttall Window Double-spectrum-line Interpolation FFT

The fast Fourier transform(FFT) had already become a main method of the electrical harmonic analysis since it’s easily realized in embedded system,but there were difficulties in performing synchronized sampling and integral period truncation in the electric power harmonic analysis,and the accuracy of the analysis result would be disturbed by the frequency leakage.Some efforts had been made,such as the utilization of window functions and interpolation algorithms,to improve the accuracy of harmonic parameters computation by FFT.The sidelobe characteristic of Nuttall window and the double-spectrum-line interpolation algorithm were both discussed,an approach for electrical harmonic analysis based on the Nuttall window double-spectrum-line interpolation FFT was proposed,the applicable rectification formulas of the double-spectrum-line interpolation was obtained by using polynomial curve fit functions,and subsequently calculating burden was dramatically reduced.The simulation results indicate that,by using the approach presented in this paper under the non-synchronized sampling and non-integral period truncation conditions,the errors of calculating amplitudes of 21 orders harmonics are no more than 0.000 9%,as well as that of calculating phases no more than 0.04%.