三绕组变压器差动电流计算与差动保护新技术

Calculation of Three-Winding Transformer Differential Current and New Differential Protection Technology

变压器调挡过程中往往由于差动保护定值整定时的变压器挡位与实际运行挡位不一致产生差流,并触发差动保护相关告警,威胁电网稳定运行。以一起某110kV变电站三绕组变压器差动保护CT报警缺陷处理实例为依据,介绍了故障排查步骤,并以现场保护二次电流记录为基础,探讨了三绕组变压器差动电流大小计算方法,采用工作现场数据计算变压器差动保护告警时的差流大小,为类似事件的计算分析提供参考,并提出预防措施。

In the process of shifting gears of transformer,differential current is often caused by the inconsistency between the gear at the differential protection value setting of the transformer and the gear in the actual operation of the transformer,with differential protection alarm triggered,which will threaten the stable operation of power grid.In an example of CT alarm defect treatment of differential protection of three-winding transformer in a 110kV substation,this paper introduced the troubleshooting steps,and discussed the calculation method of differential current of three-winding transformer based on the records of secondary current in field protection,where the field data was used to calculate the differential current when transformer differential protection alarm was triggered,so as to provide references for the calculation and analysis of similar events as well as the preventive measures.