基于间谐波泄漏估算的谐波间谐波分离检测法

Harmonics and Interharmonics Separate-Detection Method Based on Estimation of Leakage Values Caused by Interharmonics

某次谐波附近存在间谐波时,信号会发生闪变。本文以IEC61000?4?7推荐的测量环境为前提,提出了一种频谱分离法用于检测谐波及引起闪变的主导间谐波。首先研究了同步采样下谐波、间谐波之间的频谱干扰特性;根据间谐波离散频谱泄漏的特点,利用谐波频点左右谱线,通过变量重组,估算其在谐波频点上的泄漏值;用泄漏值修正原始频谱得到准确的谐波参数;原始信号减去重采样后的拟谐波信号得拟间谐波信号,通过时域补零或CZT求得间谐波参数。仿真算例和实测分析表明,该方法能够有效地分离信号中的谐波和间谐波成分、抑制它们之间的频谱干扰;当某一间谐波与谐波频率差小于5Hz时,仍能较为准确地提取出其中的间谐波参数。

The interharmonics which are closed to harmonics may bring on signal flicker.Based on the specified signal processing recommendations by IEC61000-4-7,this paper presents a new spectrum separation method for detecting harmonics and the main interharmonics in power system.Firstly,the spectral interference between harmonics and interharmonics under synchronized sampling is investigated.According to the characteristic of discrete spectral leakage,leakage values at harmonic frequencies caused by interharmonics can be estimated by using the spectral lines nearby and the technique called variable reorganization.Then the harmonic parameters can be corrected by subtracting leakage value from the original spectrum.Interharmonic signal in time-domain can be got by subtracting the resampled harmonic signal from the original sampled data,then zero-padding or CZT is use to detect the corresponding parameters.From the analysis of simulations and field test,the validity of the proposed method is proved;it can separate harmonics and interharmonics effectively,and strongly restrain the spectral interruption;extract interharmonic component even when the frequency difference between the harmonic and interharmonic is less than 5Hz.