基于Nuttall窗四谱线插值FFT的电力谐波分析

快速傅里叶变换(Fast Fourier Transform, FFT)在非同步采样和非整数周期截断时难以精确检测谐波各参数。加窗和插值算法可提高FFT的精确度。分析了Nuttall窗的频谱特性，提出了基于Nuttall窗四谱线插值FFT的电力谐波分析算法。该算法充分利用峰值谱线频点附近的四条谱线进行加权运算以提高谐波分析精度，运用多项式拟合推导出实用的插值修正公式。仿真结果验证了在非同步采样时，该算法检测谐波的精度更高，有效地抑制了频谱泄漏。

Harmonic analysis of power system based on Nuttall window four-spectrum-line interpolation FFT

There is difficult for Fast Fourier Transform to obtain the exact harmonic parameters in situation of non-synchronized sampling and non-interger cycle truncation. Utilization of window functions and interpolation algorithms can improve the accuracy of FFT. The spectral characteristics of Nuttall window are analyzed and an algorithm based on Nuttall window four-spectrum-line interpolation FFT is proposed to analyze electric power harmonic. The algorithm has improved the accuracy of harmonic analysis by using weighted arithmetic of four spectral lines near the peak spectrum-line frequency point. The applicable formulas are obtained by fitting of polynomials. Simulation results verify a higher accuracy of harmonic analysis and a better effect of restraining the spectral leakage in non-synchronized sampling by using the algorithm.