特高压变压器磁屏蔽接地线断裂引起局部放电异常的检测与分析

针对特高压某站主变压器交接试验中出现的局部放电异常现象，排除了外部干扰、试验检测系统的影响，分析了变压器磁屏蔽及其接地的结构特点，对放电部位进行定位。首次发现了特高压主体变压器内存在的磁屏蔽接地线断裂重大缺陷，该缺陷导致磁屏蔽悬浮放电产生大量乙炔。更换磁屏蔽接地后变压器运行正常，成功消除了该缺陷。分析处理结果表明，综合运用局部放电试验方法、超声波定位方法和油中溶解气体色谱分析能够准确判断缺陷类型并进行精准定位。

Detection and analysis of abnormal partial discharge caused by the fracture of magnetic shielding ground line in UHV transformer

Based on the detection and analysis of the abnormal phenomenon in UHV transformer partial discharge test, this paper eliminates the influence of external disturbance and the test system, analyzes the structure characteristics of transformer magnetic shielding and grounding, and carries out the discharge location. It first discovers the fracture of magnetic shielding ground line in UHV transformer, which causes the magnetic shielding floating potential discharge and thereby produce a large amount of acetylene gas. The defect is eliminated successfully, and then the transformer operates normally by replacing the magnetic shielding ground line. The analysis shows that the integrated use of partial discharge test, ultrasonic positioning method and oil chromatographic analysis can accurately diagnose defect types and position them. This work is supported by National High-tech R & D Program of China (No. 2015AA050204).