基于Nuttall窗插值FFT的谐波分析方法

Harmonic analysis based on Nuttall window interpolation FFT

用于电力系统谐波分析的加窗插值FFT算法中,Hanning窗算法运算量小,但测量精度较低,Blackman-Harris窗算法分析精度高,但插值修正公式计算复杂。提出一种基于Nuttall窗插值FFT的谐波分析方法。推导了Nuttall窗的显式插值系数公式,以及谐波的频率、幅值和相位的插值修正公式。通过消除基波对2次谐波的频谱干涉,调整2次谐波插值系数的估算方法,提高算法的分析精度。对该算法与Hanning窗、4项Rife-Vincent(Ⅲ)窗和Blackman-Harris窗插值FFT算法进行Matlab仿真对比,验证了该算法具有更高的分析精度。对微波炉电流的实验研究进一步验证了所提算法的有效性。

In the windowed interpolation FFT algorithms of harmonic analysis for power system,Hanning algorithm has small computation but low measuring accuracy,while Blackman-Harris has high precision but complex interpolation formula.An algorithm based on Nuttall interpolation FFT is proposed for harmonic analysis.The explicit interpolation coefficients formula of Nuttall window is derived,as well as the estimation formulas of harmonic frequency,amplitude and phase.The estimation of the second harmonic interpolation coefficients is optimized to enhance the accuracy by eliminating the spectral interference of the fundamental component with the second harmonic.Comparison with Hanning,four Rife-Vincent（Ⅲ） and Blackman-Harris interpolation FFT methods is carried out by Matlab simulation,which verifies its higher analysis accuracy.An experiment on microwave oven current further demonstrates its validity.