一起主变零序保护越级跳闸事故分析与处理

Analysis and countermeasure of leapfrog trip in main transformer zero-sequence protection

介绍了一起主变零序保护越级跳闸事故的相关情况,通过对现场相关电气设备进行了特性试验、绝缘检查、二次回路测量等,并就保护动作报告和事故录波进行分析,得出事故原因:1、线路保护CT极性接反;2、主变中性点CT变比配置不合适;3、中性点土壤阻值超标。以上三个问题的存在,造成主变零序保护越级跳闸事故。针对运行中的缺陷提出了:接入保护装置的电压、电流极性必须正确;降低土壤电阻率,确保接地电阻满足规程的要求等纠正措施及解决方案。

This paper introduces main transformer together with the protection of zero-sequence leapfrog trip-related accidents. Acoording to on-site relevant electrical equipment characteristics of the test, insulation inspection, the secondary loop measurement, and the analysis of reporting and action on the protection of the incident waves, the paper points out the causes of the accident： 1. the line to protect polar is the anti-CT; 2.the main transformer neutral CT configuration change is inappropriate; 3.neutral soil resistance is out of standard. The three reasons, result in zero change principal protection order leapfrog tripping accidents. It presents the countermeasures for the deficiencies in the operation, including the access protection device voltage and current polarity must be correct, reducing soil resistivity earthing resistance,and ensuring that procedures meet the requirements.