差流动态追忆法的研究

母线保护中存在母线经高阻接地故障易导致差流特性不明显和母线区外故障易造成电流互感器严重饱和的现象。针对此在SGB750数字式母线保护装置中采用了突变差量电流快速启动及常规差电流慢速积分启动的双启动原理来区分检查各种特性的差流;采用差流动态追忆法抗区外故障电流互感器饱和,通过提取差流的突变量值和对饱和拐点进行分析以区分区内外故障。大量的动态模拟试验证明,这2个原理能抓住故障电流互感器传变特性,快速有效地判断出系统所发生的故障类型,判据准确可靠。

Research on differential current dynamic reminiscing principle

In the bus protection,differential current characteristics are indistinct for the bus grounding fault via the big resistance and the out-zone fault often causes current transformer seriously saturated.The dual start-up principle is adopted in SGB 750 digital bus protection,which uses the differential current sudden change rapid start-up and the differential current integral start-up to distinguish various differential current characteristics,and uses the differential current dynamic reminiscing principle to resist the out-zone fault current transformer saturation by extracting the differential current sudden change and analyzing the saturation inflexion to differentiate between the external and internal fault.Dynamic simulation experiments verify that,introduced principles can fetch current transformer characteristics and distinguish fault types of power systems quickly and effectively.The criterion is correct and credible.