根据白噪声在S 变换域服从2 分布且平均功率谱与频率成正比的特点，提出了基于S 变换与奇异值分解( SVD) 的局部放电( PD) 信号去噪方法。首先对带噪PD信号进行S 变换，得到时频矩阵; 接着利用SVD 与奇异值差分谱理论，确定PD 信号发生的时间与个数，得到白噪声区域; 然后通过构造与频率成正比的线性方程，采用硬阈值法对时频矩阵进行处理，完成PD 信号的第一次去噪; 最后利用SVD 对PD 信号进行第二次去噪。仿真和实测信号的分析结果表明，文中方法的去噪效果优于小波阈值法，且该方法更简便快捷。

According to the characteristics that white noise follows 2 distribution in the S-transform domain and its average power spectrum is linearly correlated with the frequency，a partial discharge signal denoising method based on S-transform and singular value decomposition was proposed． Firstly，the time-frequency matrix of noisy partial discharge signals was obtained by S-transform． Secondly，the time and number of PD signal were determined by singular value decomposition and singular value difference spectrum theory，and the white noise area was obtained．Then the first denoising of PD signal was carried out by constructing the linear equation in proportion to frequency and dealing with the time-frequency matrix with hard threshold method． Finally，the second denoising of PD signal was done with singular value decomposition theory． Both the simulation and the measured signals show that the denoising effect of the proposed method is better than that of the wavelet threshold method，and the method is simpler and faster．