基于四项余弦窗三谱线插值FFT的谐波检测方法  

Harmonic detection approach based on 4-term cosine window triple-spectrum-line interpolation FFT

作　　者：牛胜锁[1] 梁志瑞[1] 张建华[1] 苏海锋[1] 

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,保定071003

出　　处：《仪器仪表学报》2012年第9期2002-2008,共7页Chinese Journal of Scientific Instrument

摘　　要：快速傅里叶变换(fast Fourier transform,FFT)在非同步采样情况下存在较大的误差,为了减小非同步采样对FFT的影响,通过选择旁瓣性能良好的4项5阶Nuttall窗结合插值FFT进行电力谐波检测。推导了实用的三谱线插值修正公式,利用谐波频点附近的三根离散频谱的幅值确定谐波谱线的准确位置,进而得到谐波幅值、频率及相位的修正公式。仿真结果验证了该算法在非同步采样时,与加Hanning窗和Blackman-Harris窗插值FFT相比有更高的分析准确度,同时,在加相同窗函数情况下,与双谱线插值修正算法相比也具有更高的准确度。仿真结果还验证了测量数据含有白噪声时,算法仍然具有较高的准确度。基于该算法的检测仪器的实测结果也验证了算法的有效性。When used in a non-synchronized sample sequence the fast Fourier transform（FFT） has large error; to reduce the influence of an unsynchronized sample sequence on FFT, this paper carries out electrical harmonic detection using a good sidelobe characteristic 4-term continuous fifth derivative Nuttall window combined with FFr interpolation method. A triple-spectrum-line interpolation correction formula is deduced, and the amplitudes of three neighboring spectrum lines near the harmonic frequencies are used to locate the accuracy position of the harmonic spectrum lines, and then the correction formulas of amplitude, frequency and phase of the harmonic can be obtained. The simulation results have verified that the algorithm has a better analysis precision than Hanning window and Blackman-Harfis window interpolated FFTs in non-synchronized sampling; at the same time, the algorithm has a better precision than double-spectrum-line interpolation correction algorithm when the same window is used. The simulation results have also proved that the algorithm has very high precision when the data contain white noise. The actual measurement results of the instrument based on the algorithm also have verified the effectiveness of the algorithm.

关 键 词：谐波分析 频谱泄漏 快速傅里叶变换 4项5阶Nuttall窗 三谱线插值 

分 类 号：TM935[电气工程—电力电子与电力传动]