基于广义S变换与数学形态学的局部放电窄带干扰抑制方法

Narrowband Interference Suppression of Partial Discharge Based on Generalized S Transform and Mathematical Morphology

针对高压电力设备局部放电信号受周期性窄带干扰影响大的问题,提出了一种基于广义S变换与数学形态学的局部放电窄带干扰抑制方法。该方法可以从染噪局部放电(partial discharge,PD)信号中分离出原始PD信号和窄带干扰信号的时频谱图,从而在时频域内准确辨识出窄带干扰和原始PD信号,避免强能量的窄带干扰掩盖原始PD信号时频特征的问题。再利用总体最小二乘不变旋转矢量技术准确估计窄带干扰的特征参数,以抑制染噪PD信号中窄带干扰。对仿真和实测PD信号开展窄带干扰的抑制测试,测试结果表明:该文所提方法可以有效分离出染噪PD信号时频谱图中窄带干扰和PD信号,提高了时频分析的准确率;同时相比于传统的快速傅里叶变换(fast Fourier transform,FFT)算法谱最小熵解卷积滤波法和自适应奇异值分解法,该文方法能够有效抑制小幅值的窄带干扰,具备更好的窄带干扰抑制效果,以恢复局放信号的波形特征。

To solve the problem that the partial discharge(PD) signals of high voltage power equipment is seriously affected by the periodic narrowband interferences, a narrowband interference suppression of the PD signals based on the generalized S transform and the mathematical morphology is proposed in this paper. The proposed method first separates the time-frequency spectrum images of the original PD signals and the narrowband interferences from the noise-polluted PD signals, accurately identifying the original PD signals and the narrowband interferences in the time-frequency domain and avoiding the problem that the strong narrowband interferences cover the time-frequency characteristics of the original PD signals. Then, the total least squares-estimation of the signal parameters via the rotational invariance technique is used to accurately estimate the characteristic parameters of narrowband interferences in order to suppress the narrowband interferences in the noise-polluted PD signals. The narrowband interference suppression tests are performed in the simulated and the measured PD signals. From the test results, the proposed method succeeds in effectively separating the narrowband interference signals and the PD signals from the time-frequency spectrum images of the noise-polluted PD signals, improving the accuracy of time-frequency analysis. Compared with the traditional FFT spectrum minimum entropy deconvolution filtering method and the adaptive singular value decomposition method, the proposed method effectively suppresses the narrowband interferences with small amplitudes, obtaining a better narrowband interference suppression result and restoring the waveform characteristics of the PD signals.