Nuttall最小旁瓣窗的插值FFT谐波分析-电测与仪表.DOC

基于四项最低旁瓣Nuttall窗的插值FFT谐波分析* 李得民，（，(fast Fourier transform, FFT)在非同步采样和非整数周期截断时存在频谱泄漏，无法精确得到谐波参数。为了减少非同步采样对FFT的影响，本文采用四项最低旁瓣Nuttall窗结合双谱线插值FFT进行谐波分析。文章分析了四项最低旁瓣Nuttall窗的频谱特性，提出了基于四项最低旁瓣Nuttall窗插值的分析算法，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，该算法与加Blackman窗和Blackman-Harris窗的插值FFT相比具有更高的精确度，更好的抑制了频谱泄漏。 关键词：；；中图分类号：TM 文献标识码： 文章编号：1001-1390（201）00-0000-00nterpolation FFT algorithm based on 4-term minimum sidelobe Nuttall window Li Demin, He Yigang ( School of Electrical Engineering and Automation, Hefei University of Technology, Hefei 230009, China) Abstract：n situation of non-synchronized sampling and non-integer cycle truncation for fast Fourier transform (FFT) and the high measurement accuracy of harmonic parameters can not be detected. To reduce the influence of non-synchronized sampling on FFT, this paper adopts harmonic analysis using the 4-term minimum sidelobe Nuttall window combined with double-spectrum-line interpolation FFT algorithm. The spectral characteristics of 4-term minimum sidelobe Nuttall window are analyzed in this paper and an algorithm based on 4-term minimum sidelobe Nuttall window interpolation FFT has been proposed. The applicable formulas are obtained by fitting of polynomials. The simulation results show that the algorithm has a better detection precision than Blackman window and Blackman-Harris window interpolation FFT algorithms in non-synchronized sampling which will control the spectral leakage more efficiently. Keywords: non-synchronized sampling, spectral leakage, harmonic analysis, 4-term minimum sidelobe Nuttall window, polynomial fitting0 引言 电力系统中使用的发电机、电力电子装置等非线性设备，在实现电能转换的同时，也产生了谐波，导致电能质量恶化[1]，使绝缘设备损坏。精确的检测各次谐波，对电力系统的安全稳定运行具有重要意义。 快速傅里叶变换（Fast Fourier Transform, FFT）是目前分析电力谐波最主要的工具，同步采样时，FFT算法可以精确的检测谐波各参数。但电网频率不恒定，即使采用离散锁相环技术，也很难严格实现同步采样[2]。当被测信号因频率改变导致非同步采样时，会产生频谱泄漏现象[3]。研究表明，时域加窗可有效抑制频谱泄漏，采用性能优良的窗函数可以提高FFT算法的分析精度[4]，对计算结果进行插值校正可以减少栅栏效应引起的误差[5]。国内外学者提出基于Blackman窗[6]，Blackman-Harris窗[7]，Nuttall窗[8]等加窗插值FFT分析方法，