Power Harmonics Measurement Based on Windows and Interpolated FFT(Ⅰ)Study of Windows
Pan Wen; Qian Yushou; Zhou E(Southeast University)
The spectral leakage errors of DFT caused by the non-synchronous sampling process are analyzed in this paper. In order to decrease the effect of harmonic interference. the constructed windows based on cosine windows are used for the sampling data windowing. The general magnitude frequency charactenstic formulas of the windows and the windowed signals are precisely derived. The calculations results show that the Hanning window, the Blackman window and the 4term BlackmanHarns window,respectively compared with the windows of the same terms,can largely reduce the harmonic interference errors and when the measuring time is more than four signal.periods, the 4-term Blackman-Harris is best to prefer.