绝缘油种类对油纸绝缘直流空间电荷特性的影响

In converter transformer, oil-paper insulation structure is mainly composed of mineral oil and insulating paper, while vegetable oil is rarely used. In order to study the influences of different types of insulating oil on the space charge characteristics of oil-paper insulation, two kinds of oil-paper insulation structures, KI 50X mineral oil and FR3 vegetable oil combined with Kraft insulation paper, were prepared. The space charge waveform distribution of two kinds of oil-paper samples under DC electric field was measured by the pulsed electro-acoustic method when they were under pressurization and depressurization. The space charge accumulation and dissipation characteristics of mineral oil-paper and vegetable oil-paper were obtained. The results show that, in the pressurization stage, the FR3 sample accumulates more space charge; in the depressurization stage, the FR3 sample has less residual space charge. The internal traps of the two oil-paper samples are mainly shallow energy level traps, and FR3 sample has more shallow energy level traps, which can enable the space charge to dissipate faster. KI 50X sample has more deep energy level traps and more residual space charge. From the perspective of space charge characteristics, vegetable oil-paper can be applied to the insulation structure of converter transformer.