In order to suppress the periodic narrow-band interference and white noise in the partial discharge（PD）signal

a denoising method based on the optimized variational mode decomposition（VMD） and threshold of the modes is proposed.Firstly

aiming at the problem that the VMD algorithm may under-decompose or over-decompose the noise signal

a method of K value determination based on spectrum analysis and quantile is proposed

and the narrow-band interference and high frequency white noise are removed by using kurtosis;Secondly

aiming at the residual white noise in the PD-dominant mode

a noise standard deviation estimation method based on two statistical characteristics of decomposing white noise with VMD is proposed to determine the threshold

and the interval threshold function is introduced to further denoise the PD-dominant mode.The denoising method was applied on the simulative and field measured signal

compared with the traditional methods

the results show that the proposed method can preserve the characteristics of the PD signal better while suppressing the noise more effectively.