An Improved Window and Interpolation Algorithm Using Trispectrum for Measuring Power Harmonics Based on FFT

Fast Fourier Transform is quite effective in power harmonic measurement. But due to the spectral leakage caused by asynchronous sampling process, this method usually cannot achieve a satisfying accuracy. So the window and interpolation method is presented to improve it. In this paper, first the NUTTALL window is employed to decrease the long-range leakage and three spectrum lines are chosen to reduce the short-range leakage by interpolation. Then the magnitude is amended through weighed average method to improve the accuracy. Finally a simulation experiment using MATLAB is done and the result shows that the improved algorithm can obtain a much better accuracy.