Electromagnetic voltage transformers (PTs) are prone to ferromagnetic resonance due to external disturbances, causing the fuse on the high-voltage side of the PT to burn out and endangering the stable operation of the power system "Q1" Text="This is to inform you that corresponding author and email id have been identified as per the information available in the Copyright form." . In the article, the instantaneous symmetrical component method is first used to calculate the resonant overcurrent caused by PT saturation, and the influencing factors of PT transient overcurrent are obtained. Using ATP-EMTP electromagnetic transient simulation software to build a simulation model of 10 kV distribution network, considering the nonlinear characteristics of PT excitation winding, an ideal transformer and a 98 type nonlinear inductor parallel resistor are used to establish the PT model; The PT open zero sequence voltage signal obtained from simulation is decomposed into a series of product function (PF) components through local mean decomposition (LMD). The amplitude and frequency information of each order PF component is extracted through Teager energy operator (TEO), and then integrated along the time axis to obtain the LMD-TEO marginal energy spectrum. Frequency division resonance and high-frequency resonance are identified based on the frequency value corresponding to the maximum peak of the LMD-TEO energy spectrum; Using Hilbert phase difference to calculate the phase difference of zero sequence current and zero sequence voltage of each outgoing line L1, L2, L3 after PT resonance and single-phase grounding fault, in order to identify power frequency resonance.