一起电抗器差动保护误动事故的分析和对策  

Analysis on Mal-operation of Reactor Differential Protection and Its Strategy

作　　者：包顺先[1] 韩安兵 李辉 

机构地区：[1]南京南瑞继保电气有限公司,江苏南京211111 [2]国网泸州供电公司,四川泸州646000

出　　处：《四川电力技术》2018年第1期53-55,共3页Sichuan Electric Power Technology

摘　　要：分析了一起在变压器低压侧投入并联电抗器时电抗器差动保护的动作行为,指出CT暂态饱和是引起差动保护误动的根本原因。电抗器差动保护采用比率制动特性和二次谐波闭锁,在一定程度上可以防止CT饱和所引起的误动,当电抗器相电流比较小、制动电流比较小时,比率制动特性不能起到应有的作用。此外,CT饱和后,差流中二次谐波含量很低,导致二次谐波闭锁失效。提出了一种利用差动电流的直流分量和基波分量的比值来修正差动电流的方法,该方法可以有效地防止CT暂态饱和所引起的差动保护误动。理论和实践表明,采用该方法后该电抗器再未发生投入电抗器的误动事故。The behavior of reactor differential protection is analyzed when switching on shunt reactor at the low voltage side of transformer , and it is pointed out that CT transient saturation is the root cause of triggering mal - operation. Applying ratio - brake characteristic and second harmonic blocking can avoid maloperation to a large extend, however, in the case of small phase current and small brake current, the ratio - brake characteristic cannot play its due function. Furthermore, after CT saturation, second harmonic in differential current is very low, which will cause second - harmonic blocking invalid. A new algorithm is presented to avoid mal - operation caused by CT transient saturation. This algorithm makes use of the ratio of DC and fundamental component to get a correction factor, and then get a corrected differential current. Theory and practice show that there is not any mal - operation of shunt reactor differential relaying since this new algorithm is applied.

关 键 词：电抗器 差动保护 暂态饱和 误动 

分 类 号：TM772[电气工程—电力系统及自动化]