According to the unstability of partial discharge pulse signals

a joint time-frequency analysis method was put forward to process the signals to obtain their characteristics in time-frequency domain.Since the wigner-ville distribution which belongs to the Cohen class time-frequency energy distribution is commonly used at present for processing unstable signals

a simulated PD pulse was chosen as the object to investigate its original WVD

smoothing pseudo Wigner distribution（SPWVD） and rearranged-smoothing-pseudo Wigner distribution（RSPWVD）.The results show that WVD is highly sensitive to the short-variation of unstable PD signal

which is more suitable to extract time-varying information.SPWVD can remove the cross-terms of interference caused by the bilinear function but reduce the time-frequency resolution.For having good time-frequency concentration

RSPWVD provides a powerful tool to evaluate parameters for single PD pulse shape

which can be used in PD pattern recognition and in-depth study of PD mechanism in electrical insulation system.