基于加窗插值FFT的电力谐波测量理论──（Ⅰ）窗函数研究

Power Harmonics Measurement Based on Windows and Interpolated FFT(Ⅰ)Study of Windows

本文首先分析了传统频谱分析方法（ＤＦＴ）引入的地漏误差，提出了用一类组合余弦窗对采样数据加权，进而减小谐波相互干扰误差的方法，并严格导出了窗的频谱特性和信号加窗后的频谱公式。对多种窗的零点特性和旁瓣特性的综合分析表明，Ｈａｎｎｉｎｇ窗、Ｂｌａｃｋｍａｎ窗和四项Ｂｌ－ａｃｋｍａｎ－Ｈａｒｒｉｓ窗能较好地抑制整数次和非整数次的谐波泄漏，测量时间大于４个信号周期时．四项Ｂｌａｃｋｍａｎ－Ｈａｒｒｉｓ窗最优。

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.