中文摘要：

长期运行换流变压器中存在由沿面放电导致的绝缘故障的现象,而针对换流变压器中交直流复合电场下老化油纸绝缘的沿面放电发展过程特性研究又相对缺乏不足.因此,采用在130℃下加速热老化方法制备不同老化程度的油纸绝缘试样,并使用CIGRE methodⅡ推荐的典型球板电极模型对不同老化程度油纸绝缘试样在不同比例交直流复合电场下的沿面放电起始电压、闪络电压以及沿面放电发展速度等特性进行了对比分析研究,同时对老化前后油纸绝缘沿面放电发展过程中放电特征参数的变化规律展开了研究.研究结果表明,随着交直流复合电压中直流电压分量的不断增大,老化油纸绝缘沿面放电起始电压和闪络电压均呈现逐渐上升的趋势,其中纯交流电压下的沿面放电起始电压和闪络电压均最低;相同电压作用下的沿面放电起始电压随着油纸绝缘老化程度的不断加剧呈现先上升后下降的趋势;随着油纸绝缘老化程度的不断增加以及交直流复合电压中直流电压分量的不断增加,油纸绝缘沿面的爬电距离不断延长、耐受时间逐渐缩短,沿面放电发展速度逐渐加快.与未老化油纸绝缘沿面放电过程放电特征参数变化规律相比,老化后沿面放电发展特征参数幅值较大,各阶段变化起伏较少,变化趋势直接明显;同时发现交直流复合电压中的直流电压分量对老化油纸绝缘沿面放电发展具有加速的作用,而且直流电压分量越高,加速作用越明显.

英文摘要：

The creepage discharge phenomenon is found in long-term operating transformers. But the characteristics of creepage discharge processes under combined AC-DC voltage do not attract much attention because of the shorter oper- ating time of converter transformers in actual cases. Therefore, we investigated the characteristics of creepage discharge processes of different aged stage oil-paper obtained by the 130 ℃ accelerated aged method under combined AC-DC vol- tage using a sphere-plate electrode configuration, which is recommended by CIGRE method II. The experimental results show that the creepage discharge inception voltage （CDIV） and creepage discharge flashover voltage （CDFV） gradually increase under higher componental DC voltage, and they are the lowest under the pure AC voltage. CDIV and CDFV in- itially increase then decrease in different aged stage of oil-paper under the same voltage. The creepage discharge distance and developed velocity of creepage discharge increase, and the tolerance time is shortened under the higher componental DC voltage and gradually-aged oil-paper. The amplitude of characteristic parameters of aged oil-paper is higher than that of un-aged oil-paper. The relationship of characteristic parameters is more obvious in the processes of aged oil-paper un- der combined AC-DC voltage. The componental DC voltage in combined AC-DC voltage has an accelerated effect on the creepage discharge with aged oil-paper uttder combined AC-DC voltage. The accelerated effect is more obvious under hieher comoonental DC voltage.