直流输电中换流变压器零序过流保护的探讨

Investigation on Converter Transformer's Zero-Sequence Over-Current in HVDC System

针对银川极1换流变压器在空充时Y0/Y换流变零序过流误动导致开关跳闸这一事故展开思考,通过理论分析发现,换流变压器网侧发生接地故障时,流经Y0/Y换流变压器中性点和Y0/Δ换流变压器中性点零序电流的大小有很大差异。同时,建立仿真模型并以南方电网在许继集团的换流变保护装置RTDS试验中数据和波形为佐证。综合分析后得出:对于Y0/Y换流变压器而言,其零序过流保护没有投入的必要。

An investigation is made on the accident of switch trip in Yinchuan Pole 1 converter transformer caused by zero-sequence over-current malfunction of Y0/Y converter transformer during charging period. It was found that a big difference exists between the zero-sequence current that goes through the Y0/Y converter transformer neutral point and the one that goes through the Y0/A converter transformer neutral point when the line-side earth fault occurs. A model simulation is made based on the data and wave shape of XJ GROUP＇s converter transformer protective device-RTDS used in CSG＇s project. It is concluded through synthetic analysis that the zero-sequence over-current protection is not necessary for Y0/Y converter transformer.