Study of PT Fuse Melting Triggered by Low Frequency Nonlinear Oscillation in Distribution Network

The generation and suppression of ferromagnetic resonance in 10~35kV distribution systems have been widely studied, but there is relatively little research on the generation, development and suppression methods of ferromagnetic resonance overvoltage in 66 kV systems, and there is a lack of actual fault recording data in the field to support it. Therefore, we obtained the recorded wave data of resonant overvoltage fault of 66kV side voltage transformer in a 500kV substation, combined with the actual equipment data of the substation, established the simulation model of the substation based on ATP-EMTP electromagnetic transient simulation software, analyzed the causes and development of resonant overvoltage during charging of 66kV busbar closing breaker, and compared the simulation results with the actual recorded wave to verify the validity of the simulation model. The simulation results are compared with the actual recordings to verify the validity of the simulation model, and the resonant overvoltage suppression method of 4PT wiring is proposed by reducing the magnetic density of the voltage transformer at rated voltage, optimizing the excitation characteristics and shorting the delta winding in series with a small resistance.