电流二次回路两点接地引起主变压器差动保护区外故障误动分析

华电技术 ›› 2015, Vol. 37 ›› Issue (1): 55-57.

电流二次回路两点接地引起主变压器差动保护区外故障误动分析

(宁东供电公司，银川〓750411)

出版日期:2015-01-25 发布日期:2015-03-25

Analysis on false action of main transformer differential protection responding outside area fault caused by twopoint grounding of secondary current circuit

(Ningdong Power Supply Bureau，Yinchuan 750411，China)

Online:2015-01-25 Published:2015-03-25

摘要/Abstract

摘要： 摘要：介绍了一起330kV主变压器在其所带110kV线路发生接地故障时，主变压器差动保护动作跳闸事故，从装置录波图中发现差动保护装置在区外动作时B相电流异常增大，结合现场对CT二次回路的检查，发现B相存在两点接地现象。分析了B相两点接地时主变压器差动保护区外故障动作的原因，提出了防范措施。

关键词: 关键词：主变压器, 差动保护, 区外故障, B相电流, CT两点接地

Abstract: Abstract:An 110kV line is one of output lines of the 330kV main transformer. When a ground fault of the 110kV line occurred, the differential protection of the main transformer tripped incorrectly. The fault record figure was investigated, and it was found that when the differential protection device tripped due to the outside area fault, the phase B current increased abnormally. The CT secondary circuit site was inspected, and it was found that there was two points ground phenomenon in the secondary circuit phase B. It was analyzed that when the CT secondary circuit phase B grounded through two points, why the outside area fault can cause the differential protection of the main transformer to trip incorrectly. The preventive measures were proposed.

Key words: Keywords:main transformer, differential protection, outside area fault, phase B current, two points ground of CT

廖洪涛. 电流二次回路两点接地引起主变压器差动保护区外故障误动分析[J]. 华电技术, 2015, 37(1): 55-57.

LIAO Hongtao. Analysis on false action of main transformer differential protection responding outside area fault caused by twopoint grounding of secondary current circuit[J]. Huadian Technology, 2015, 37(1): 55-57.

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