励磁变压器差动保护五次谐波闭锁新判据  

New criterion for fifth harmonic blocking differential protection of excitation transformers

作　　者：陈赟[1] 杨定乾[2] 王毅[1] 

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,河北保定071003 [2]国网新疆电力公司电力科学研究院,乌鲁木齐830000

出　　处：《电测与仪表》2016年第3期93-98,116,共7页Electrical Measurement & Instrumentation

基　　金：国家自然科学基金资助项目(51277072);中央高校基本科研业务费专项资金资助项目(2014ZZD11)

摘　　要：励磁变压器为谐波电流含量很高的负载变压器,其比率制动特性曲线斜率低,易受谐波电流的影响,存在因变压器过励磁导致保护误动作的情况,因此,需要为比率制动辅以过励磁闭锁判据。传统的过励磁闭锁判据存在解锁延迟、解锁失败的缺陷,文中提出了一种以差动电流中工频负序分量为辅助判据的新型五次谐波闭锁判据。通过MATLAB/Simulink对新旧两种判据的仿真分析,在负载为整流桥的励磁变压器系统中验证了所提新判据的有效性,解决了传统判据易受故障电流谐波分量影响的缺陷,解锁速度更快、解锁范围更广,更适用于励磁变压器这类谐波含量较高器件的比率差动保护。Excitation transformer as a load transformer includes large harmonic current,which may influence its lowslope percentage restraint characteristic curve and cause the false protection because of over excitation. Therefore,it is necessary to design an over-excitation blocking criterion of percentage differential protection for the excitation transformer. Due to defects in the traditional over-excitation blocking criterion,such as unlock delay and unlock failure,this paper proposes a new type of fifth harmonic blocking criterion which uses the power frequency negative sequence components in the differential current as the auxiliary criterion. The traditional and proposed criteria were compared by MATLAB / Simulink,and the effectiveness of the proposed criterion was proved. The simulation result shows that the new blocking element can not only unlock fast and wide,but also avoid the influence of harmonic current in the system with rectifier load,which is more suitable for the percentage differential protection for devices such as excitation transformer with large harmonic current.

关 键 词：励磁变压器 五次谐波闭锁判据 工频负序过电流 比率差动保护 

分 类 号：TM614[电气工程—电力系统及自动化]