绝缘油老化对油纸绝缘介质空间电荷形成及迁移特性的影响

Influence of Oil Aging on the Formation and Migration Behavior of Space Charge in Oil-paper Insulation Dielectrics

探索绝缘油老化或绝缘纸老化对油纸绝缘介质在老化过程中空间电荷形成及迁移特性的影响,能为有效抑制油纸介质空间电荷的形成提供科学依据。首先在130℃下将绝缘油进行22 d加速热老化,并对其老化状态进行表征;然后通过电声脉冲法测量由不同老化程度绝缘油浸渍的油纸试品,分析在加压、瞬时去压和去压情况下绝缘油老化对油纸试品直流空间电荷动态行为的影响;最后通过计算分析绝缘油老化对油纸试品的空间电荷总量、表面陷阱能级分布和电场畸变率的影响。结果表明:在负极性电源电压下,贴近阳极(铝板)侧绝缘纸层内注入的正电荷密度以及在靠近阳极侧绝缘纸–绝缘纸界面处积聚的负电荷密度均随绝缘油老化程度加深而增大;绝缘油老化越严重,相应绝缘油浸渍油纸试品的空间电荷总量、表面陷阱能级密度和电场畸变率也越大。

Investigating the influence of oil aging or insulation paper aging on the formation and migration of space charge in oil-paper insulation dielectrics during its ageing process is helpful to provide the method to restrain the space charge formation. In this paper, the insulation oil was thermally aged at 130 ~C for up to 22 days and its ageing condition was identified. The space charge behavior of the oil-paper sample impregnated with oil aged for different times was investigated by the pulsed electro-acoustic （PEA） method. The space chargemeasurements were taken at various times during the stressing period of both voltage-on and voltage-off（short-circuit condition）, as well as the decay process. The influence of oil ageing on the total charge amount, the surface trap energy density and the electric field distortion was analyzed. Results show that under the negative polarity power supply, the more the deterioration of the oil, the larger the maximum charge density of positive charge injected into the paper near to the anode and the negative charge accumulated at the paper-paper interface near to the anode. The total amount of charge, the surface trap energy density and the electric field distortion of the oil-paper sample increase with the oil aging degree.