Ji Hongxin, Tang Zijian, Zheng Chao, Liu Xinghua, Liu Liqing
School of Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, China.
College of Mechanical and Electronic Engineering, Shandong Agricultural University, Tai'an 271018, China.
Sensors (Basel). 2025 Jun 30;25(13):4089. doi: 10.3390/s25134089.
Partial discharge (PD) in insulators will not only lead to the gradual degradation of insulation performance but even cause power system failure in serious cases. Because there is strong noise interference in the field, it is difficult to accurately locate the position of the PD source. Therefore, this paper proposes a three-dimensional spatial localization method of the PD source with a four-element ultra-high-frequency (UHF) array based on improved wavelet packet dynamic threshold denoising and the Gxx-β generalized cross-correlation algorithm. Firstly, considering the field noise interference, the PD signal is decomposed into sub-signals with different frequency bands by the wavelet packet, and the corresponding wavelet packet coefficients are extracted. By using the improved threshold function to process the wavelet packet coefficients, the PD signal with low distortion rate and high signal-to-noise ratio (SNR) is reconstructed. Secondly, in order to solve the problem that the amplitude of the first wave of the PD signal is small and the SNR is low, an improved weighting function, Gxx-β, is proposed, which is based on the self-power spectral density of the signal and is adjusted by introducing an exponential factor to improve the accuracy of the first wave arrival time and time difference calculation. Finally, the influence of different sensor array shapes and PD source positions on the localization results is analyzed, and a reasonable arrangement scheme is found. In order to verify the performance of the proposed method, simulation and experimental analysis are carried out. The results show that the improved wavelet packet denoising algorithm can effectively realize the separation of PD signal and noise and improve the SNR of the localization signal with low distortion rate. The improved Gxx-β weighting function significantly improves the estimation accuracy of the time difference between UHF sensors. With the sensor array designed in this paper, the relative localization error is 3.46%, and the absolute error is within 6 cm, which meets the requirements of engineering applications.
绝缘子中的局部放电（PD）不仅会导致绝缘性能逐渐退化，严重时甚至会引发电力系统故障。由于现场存在强烈的噪声干扰，难以精确确定局部放电源的位置。因此，本文提出了一种基于改进小波包动态阈值去噪和Gxx-β广义互相关算法的四元超高频（UHF）阵列局部放电源三维空间定位方法。首先，考虑现场噪声干扰，利用小波包将局部放电信号分解为不同频段的子信号，并提取相应的小波包系数。通过使用改进的阈值函数处理小波包系数，重构出失真率低、信噪比（SNR）高的局部放电信号。其次，为了解决局部放电信号首波幅度小、信噪比低的问题，提出了一种基于信号自功率谱密度并通过引入指数因子进行调整的改进加权函数Gxx-β，以提高首波到达时间和时差计算的准确性。最后，分析了不同传感器阵列形状和局部放电源位置对定位结果的影响，找到了合理的布置方案。为验证所提方法的性能，进行了仿真和实验分析。结果表明，改进的小波包去噪算法能够有效实现局部放电信号与噪声的分离，提高定位信号的信噪比且失真率低。改进的Gxx-β加权函数显著提高了超高频传感器之间时差的估计精度。采用本文设计的传感器阵列，相对定位误差为3.46%，绝对误差在6 cm以内，满足工程应用要求。
