基于Synchrosqueezing小波变换的谐波和间谐波检测方法

Harmonic and inter-harmonic detection method based on synchrosqueezing wavelet transform in power system

非线性电力元件的广泛使用使电力系统的谐波和间谐波污染越来越严重。为准确计算谐波和间谐波的参数特征,以有效克服噪声影响,提出基于Synchrosqueezing小波变换的谐波和间谐波的一种检测方法。首先对电力系统信号进行连续小波变换;然后确定同步挤压阈值,对连续小波变换结果进行同步挤压,并利用同步挤压结果计算电力信号主频率;最后,设置提取频率区间,将电力信号分解为一组内蕴模态类函数分量(IMT),并结合Hilbert变换及最小二乘拟合,精确计算噪声背景下谐波和间谐波的幅值与频率。通过模拟信号和实测信号对所提方法有效性进行了分析,实验结果表明,与Prony和HHT方法相比,本文方法通过同步挤压有效抑制了噪声干扰,谐波和间谐波的检测精度有较好的提高。

The extensive application of non-linear power components makes the harmonic pollution situation of power system increasingly severe. To effectively suppress a variety of noise, and accurately detect harmonic and inter-harmonic parameters, a harmonic detection method based on the synchrosqueezing wavelet transform （SST） and Hilbert transform is proposed. Firstly, the signal in the power system is decomposed into a set of intrinsic mode type （IMT） function components through SST. Then, instantaneous frequency and instantaneous amplitude of each IMT component are calculated through Hilbert transform. At last, the least squares fitting of instantaneous amplitude and instantaneous frequency is calculated to realize the detection of harmonic and inter-harmonic from the noisy signal. The simulation results verify the feasibility and the effectiveness of the proposed method, which can effectively improve the detection accuracy of harmonic and inter-harmonic.