用于谐波和间谐波检测的频谱分解法

在使用离散傅里叶变换进行电力系统谐波/间谐波分析时,若所分析信号中两频率成分过于密集,就会产生主瓣干扰。本文分析了传统方法在两频率成分发生主瓣干扰时失效的原因,在10个周波采样长度下,提出一种用于抑制主瓣干扰的改进傅里叶算法:根据频域谱线的相位特性,将两个密集频率成分的傅里叶变换结果拆分成两组谱线,分别对这个两组谱线进行频率、幅值以及相位的校正。计算机仿真算例和实测分析表明,该方法计算简单,能在抑制旁瓣干扰的同时,有效拆分出信号中频率差小于频率分辨率的谐波与间谐波成分,或两个间谐波成分,满足工程精度要求。

An Approach for Harmonics/Inter-harmonics Detection Based on Spectral Deposition

If two frequency components in the analyzed signal are too intensive,main lobe interference will generate when the discrete Fourier transform method is used to analyze the harmonics and inter-harmonics in power system.In this paper,the failure reason is analyzed when main lobe interference of two frequency components generates by using of traditional method,and an improved interpolation DFT method is put forward to restrain main lobe interference in ten fundamental harmonic sampling periods.Firstly,Based on the phase characteristics of DFT spectrum line,the Fourier transform results of two intensive frequency components are split into two corresponding groups of spectrum lines that are corrected by frequency,amplitude and phase respectively.The analysis of simulations and field test show that the calculation of proposed method is simple,and the approach can be used to split not only harmonics and inter-harmonics components of the signal with the difference of frequency less than the resolution of frequency,but also the harmonics components of two inter-harmonics,which meet the accuracy requirement of engineering.