Characteristics of partial discharge in oil-paper insulation system under high frequency voltage

Increasing frequency is favorable to boost the efficiency of transporting electricity, but it leads to critical insulation challenge inside transformer. To explore the deterioration characteristics of oil-paper insulation system under high-frequency voltage, a column-plate model is adopted to simulate the surface discharge defect and an experimental platform for partial discharge test is established. Tests under high-frequencies of 10 kHz, 20 kHz and 30 kHz and power frequency of 50 Hz are carried out when constant voltages are applied. Video camera is taken to observe the column-plate model, and Rogowski coil is used to collect the partial discharge (PD) signal. Then characteristics of partial discharge signals and dissolved gas under different frequencies are compared and analyzed. Conclusions are drawn that the content of gas produced from oil-paper insulation system under high frequencies are much more than that of 50 Hz, while the content of key gases especially H2 are boosted. As for the PD amplitude-phase diagram, the PD signals center on the moment when the polarity of voltage changes. Besides, the discharge phase range under high frequencies are wider than that under power frequency. Finally, the average amplitude and number of partial discharge (PD) present a peak value around 20 kHz in a single period.