In order to effectively suppress the periodic narrowband interference in partial discharge (PD) signal

a method combining shorttime Fourier transform and matrix pencil is proposed. The short-time Fourier transform algorithm is used to analyze the noisy PD signal

and to obtain the number of narrowband interference and separate noise frame and signal frame from noisy PD signal. The matrix pencil algorithm is used to estimate the narrowband interference parameters in the noise frame

and to reconstruct the narrowband interference of the entire period and suppress the narrowband interference in partial discharge. The denoising results of the simulated and measured noisy PD signals show that compared with the traditional Fourier series method and local energy ratio method

the proposed method can get the smaller residual noise and produce a good effect of narrowband interference suppression.