变电站主变压器低压系统谐振分析

Analysis on the Resonance in the LowVoltage Part of Main Transformers

通过对一起500 k V主变压器差动保护动作导致主变压器35 k V低压侧站用变压器等多台低压设备故障的事故进行设备解体和PSCAD/EMTDC仿真分析,发现35 k V站用变压器与低压电容器发生谐振。理论分析发现主变压器低压侧站用变压器与低压电容器可能产生谐振,造成为普遍性重大隐患。最后提出了增加主变压器低压侧跳闸保护联跳低压电容器组的功能来消除隐患的措施。

In this paper,an accident,in which several low voltage elements including a 35 kV station transformer were damaged by the main transformer differential protection action in an AC 500 kV station,is analyzed by transformer disintegration and PSCAD/EMTDC simulation.A resonance is found between station transformer and low voltage capacitors in most EHV/UHV stations,which is proved to be a universality significant problem by theoretical analysis.And then a measure to solve this problem is proposed by adding an inter-tripping function,which will trip the capacitor breakers as soon as the low voltage breakers of main transformer is tripped by main transformer protection.