Effect of Vibration on Partial Discharge Inception Voltage in Transformers with Needle-Plate Defects

This study investigates the partial discharge inception voltage Phase-Resolved Partial Discharge (PDIV) of needle-plate defects in oil-paper-insulated power transformers under coupled electromechanical stress conditions. By conducting meticulously designed experiments on an artificially manufactured transformers’ oil-paper insulation needle-plate defect model, under precisely-controlled vibration frequencies and amplitudes, along with variable electric field strengths, advanced sensors were used to precisely record the inception voltage. Without vibration, the partial discharge inception voltage of the needle-plate defect is 12.3 kV, and discharge pulses emerge near the voltage wave peak. When an AC voltage of 12.8 kV is applied, the measured PRPD pattern indicates that the discharge is mainly concentrated in the positive half-cycle with negative polarity. The results further show that when vibrations with frequencies of 100 Hz and 150 Hz, and amplitudes of 0.25g and 0.3g are applied, the partial discharge inception voltage of the needle-plate defect increases. Moreover, the application of vibration also exerts certain effects on the characteristics of partial discharge. Through theory and data fitting analysis, there is a complex nonlinear correlation between these factors. This study provides important insights for improving the design, operation, and maintenance of transformers, thereby promoting a more reliable power system.