复小波包变换抑制PD监测中周期性窄带干扰

为了有效抑制PD测量中的周期性窄带干扰,采用相同滤波器构造小波包和"保持实小波包滤波器的幅频特性,改变其相频特性"构造复小波的方法,构造了与相应实小波包具有相同幅频特性和与相应复小波具有相同相频特性的复小波包;给出了构造复小波包的具体方法,并用描述波形相似程度的NCC和VTP参数以及幅值相对误差,对原始PD仿真信号分解后直接重构的效果进行了定量评价,证明了复小波包构造的正确性和具有很好还原非平稳脉冲信号的能力。最后,用复小波包变换技术对含有不同频率、不同强度窄带干扰的PD混合仿真和实测信号进行了去噪应用,解决了窄带干扰频率在检测仪器频带内用硬件滤波对局放信号有较大损失和用小波包变换去噪效果差的难题。

Suppressing PD's Periodicity Narrow Band Noise in the PD Measurement by Using Complex Wavelet Packet Transform

In order to suppress periodicity narrow band noise in PD measurement,by using the same filter to construct wavelet packet and by remaining phase spectrum of real wavelet packet filter and changing its amplitude-frequency characteristic,complex wavelets packet is constructed with the same amplitude-frequency characteristics of corresponding real wavelet packet and the same phase spectrum of corresponding complex wavelets,and then give the specific method of constructing complex wavelets packet,evaluate the effect of original PD simulative signals' direct reconstruction after decomposition by using Normalized Correlation Coefficient (NCC) and Variational Trend Parameter (VTP) also and the relative error of the amplitude,verify the capability of restore Non-stationary Oscillating Partial Discharge Signals effectively and the correctness of the complex wavelets packet's construction. At last,complex wavelets packet is used to denoise PD admixture simulative and measured signals with different frequency and strength noises,overcome the difficulty of more loss using hardware filter and bad effect using wavelets packet transformation with narrow band noise in the monitoring frequency band.