交直流复合电压作用下油纸绝缘典型缺陷放电现象及特征

Discharge Characteristics of the Typical Defects in Oil-paper Insulation Under AC-DC Compound Voltage

为实现换流变压器油纸绝缘故障诊断,搭建了一套交直流复合电压作用下油纸绝缘缺陷局部放电和油中溶解气体检测平台,选取针板模型、沿面模型和悬浮模型作为研究对象,得到每个模型不同发展阶段的局部放电和产气特性,对比了3种典型缺陷模型的特征区别。研究结果表明:1)根据3种典型缺陷模型的脉冲重复率、平均放电量和总烃体积分数变化趋势中的变化现象可以将放电过程划分为起始阶段、发展阶段和邻近击穿阶段;2)针板模型的脉冲重复率最低,沿面模型起始脉冲重复率较低但是放电后期较大,悬浮模型放电脉冲重复率最高;针板模型起始时放电量为97.5 pC,邻近击穿时超过900 pC,沿面模型起始时只有7.1 pC,随后增长到18.2 pC,而邻近击穿时也只有45.6 pC;悬浮模型起始阶段的平均放电量很大,发展阶段迅速减小到1 000 pC,邻近击穿阶段大于1 500 pC;3)针板模型在放电发展阶段总烃中以CH4为主,沿面模型在放电发展阶段中C2H2占到总烃体积分数的60.6%,悬浮模型在放电发展阶段4类烃类气体都有产出,其中C2H2气体最多。

To realize the fault diagnosis of converter transformer, we built a set of test platform for partial discharge and dissolved gas of oil-paper insulation under AC-DC compound voltage. The needle plate model, creep discharge model and suspension model were selected for this study. These differences in partial discharge and gas characteristics between different development stages and the characteristics of three typical defect models were summarized in this paper. These results show that： 1） Based on the phenomenon of the pulse repetition rate, average discharge volume and total hydrocarbon concentration, the development process could be divided into inception stage, development stage and close-to-breakdown stage; 2） The pulse repetition rate of needle model is the lowest. At the beginning, the pulse repetition rate of surface model is low, but becoming great later. The pulse repetition rate of suspension model is the greatest. The repetition discharge capacity of needle model is 97.5 p C, then become to 900 p C, surface discharge is only 7.1 p C, then become to 18.2 p C, before breakdown is only 45.6 p C. The capacity of suspension model is very great at the beginning, then decreases to 1 000 p C. 3） The main gas of needle model is CH4, the 60.6% of surface discharge is C2H2. All of the 4 kinds of gas appear in suspension model, C2H2 is the most.