摘要
分析了相电流差动方式差流、Y→△方式差流、△→Y方式差流及Y侧相电流在Y侧空载合闸时与原始磁化电流的关系,表明只有相电流差动方式的差流能完全保留原始磁化电流的特征,而其余几种方式都可能弱化某相电流的涌流特征。同时,分析了变压器对称涌流产生的原因,计算说明对称涌流中的二次谐波含量并不一定比单向涌流低。对于220 kV以上采用三单相变压器组连线的三相变压器,基于一种新型的三相变压器差动保护电流互感器配置方案,既能实现基于相电流差动方式的涌流制动方案,又不会缩短变压器差动保护的保护区。理论分析及仿真实验都表明,该涌流制动方案优于基于Y→△转角方式差流、△→Y转角方式差流及Y侧相电流的二次谐波制动方案。
The relations between the differential current and the magnetizing current are analyzed in phase current differential mode,Y→△ mode and △→Y mode,as well as between the Y-side phase current and the magnetizing current during no-load switch-on at Y side,which shows that only the phase current differential mode keeps completely the characters of the magnetizing current. The cause of symmetric inrush current is analyzed and calculation shows that the second harmonic of symmetric inrush current is not always lower than that of asymmetric inrush current. A new configuration of protection CT is proposed for 3- phase transformer over 220 kV composed of three single- phase transformers,which realizes the inrush current restraint in phase current differential mode while keeps the protective zone of transformer differential protection un-shortened. Theoretical analysis and simulative result show that the proposed scheme is better than the second harmonic restraint schemes in other three modes.
出处
《电力自动化设备》
EI
CSCD
北大核心
2008年第12期48-51,55,共5页
Electric Power Automation Equipment
关键词
变压器差动保护
励磁涌流
相位补偿
二次谐波制动
Y/△接线
transformer differential protection
inrush current
phase compensation
second harmonicrestraint
Y/△ connection
