变电站35 kV小电流接地系统选线准确率低的原因分析及改进方案

Cause Analysis and Improvement Scheme of Low Line Selection Accuracy of 35 kV Small Current Grounding System in Substation

煤化工行业对供电可靠性要求高,国能新疆化工总变电站35 kV系统采用了中性点经消弧线圈接地的小电流接地方式,文章对现有35 kV小电流接地系统选线准确率低的原因进行分析,提出通过接地变压器中性点与高压可控硅串联后接地,利用可控的强脉冲零序电流信号进行选线,再利用可调匝消弧线圈预补偿减小接地点故障电流,消除孤光接地过电压的单相接地故障管理系统改进方案,提高选线准确率,在准确确定故障支路的基础上灵活有效地确定故障处理方式,形成系统解决方案。

The Coal Chemical Industry Has High Requirements for Power Supply Reliability.the 35 kV System of the Main Transformer of Guoneng Xinjiang Chemical Co.,Ltd.Adopts the Small Current Grounding Mode in Which the Neutral Point is Grounded Through Arc Suppression Coil.This Paper Analyzes the Reasons for the Low Accuracy of Line Selection of the Existing 35 kV Small Current Grounding System,and Puts Forward That It is Grounded After the Neutral Point of Grounding Transformer is Connected in Series with High-voltage Thyristor,the Improvement Scheme of Single-phase Grounding Fault Management System,Which Uses Controllable Strong Pulse Zero Sequence Current Signal for Line Selection,and then Uses Adjustable Turn Arc Suppression Coil for Pre Compensation to Reduce Grounding Fault Current and Eliminate Isolated Light Grounding Overvoltage,Improves the Accuracy of Line Selection,Flexibly and Effectively Determines the Fault Treatment Mode on the Basis of Accurately Determining the Fault Branch,and Forms a System Solution.