Partial Discharge Growth Characteristics of Transformer Insulation Board Under AC-DC Compound Electric Field

One of the most prominent problems under operation condition of converter transformer is that the oil-paper insulation is bearing superposition of AC-DC voltage. However, there are only pure DC and AC Voltage test in the delivery test. There is large difference between test and operation condition. Therefore, it is necessary to carry out research on oil-paper insulation system partial discharge and breakdown voltage characteristics and mechanism under AC-DC compound voltage. This research set the superposition of AC-DC power and the test system. Some tests had been carried out to research the influence of initial voltage of partial discharge under different AC and DC component and summarize the law of initial partial discharge. Explored the transformer board partial discharge characteristics and mechanism under AC-DC compound voltage.