基于时-频能量群的非稳态谐波检测方法的研究

A Method for Detection of Non-stationary Harmonics Based on Time-frequency Energy Group

电力系统中稳态谐波常用的分析方法是FFT,然而FFT并不适合分析非稳态谐波。针对非稳态谐波的频谱具有一定带宽的特点,文中提出了一种基于小波包时-频能量群的检测新方法。该方法采用改进的小波包滤波器组结构,对非稳态谐波进行小波包时-频分解,使非稳态谐波在不同的时间间隔内分解到不同的频带中,得到信号的小波包时-频能量群。通过对小波包时-频能量群的检测,完成各时间间隔内的非稳态谐波分析。为了验证新方法的准确度,文中通过实验平台产生了谐波电压凸起、中断、高频扰动、暂态振荡和暂态脉冲5种典型的非稳态谐波,对新方法进行了测试,分析结果表明新方法适合分析多种典型的非稳态谐波。

The common method for analysis of stationary harmonics in power system is FFT, but it is unsuitable for non-stationary harmonics. As the spectrum of non-stationary harmonic is expanded to a band, a new method for detection--time-frequency energy group based on wavelet packet was presented in this paper. The non-stationary harmonics were decomposed in different frequency bands by wavelet packet transform in different time intervals, using an improved filter bank structure, and then all the spectrums of the non-stationary harmonic in different time-frequency areas were called wavelet packet time-frequency energy groups. Through measurement of the energy groups, the analysis of non-stationary harmonic in each time intervals was realized. To verify this new method, five typical non-stationary harmonics signals were generated through experiment platform, such as voltage swell harmonic, interruption harmonic, high frequency interferential, transient oscillation and transient disturbance. The analysis results show that, the method in this paper has extensive applicability for various non-stationary harmonics.