特高压换流站CVT二次回路故障引起过电压保护动作分析  

Analysis of Overvoltage Protection Action Caused by CVT Secondary Circuit Fault in UHV Converter Station

作　　者：乔小冬 于宏伟 QIAO Xiaodong;YU Hongwei(Yimin Converter Station of State Grid East Inner Mongolia Maintenance Company,Hulunbuir 021130,China)

机构地区：[1]国网内蒙古东部电力有限公司检修分公司伊敏换流站,内蒙古呼伦贝尔021130

出　　处：《内蒙古电力技术》2021年第S01期57-59,共3页Inner Mongolia Electric Power

摘　　要：扎鲁特换流站极Ⅰ低端三套阀保护主机换流变压器过电压保护动作,导致扎鲁特直流线路极Ⅰ低端阀组闭锁。对极Ⅰ低端换流变压器出线CVT U相二次电缆、CVT本体进行检查,发现线缆护套存在损伤情况。经过现场检查、分析及验证,确定原因为二次回路出现两次瞬时短路,使得CVT在极短的时间内被激发出两次铁磁谐振。第一次铁磁谐振产生的能量尚未被消除,再叠加第二次铁磁谐振产生的能量,导致谐振恢复过电压幅值迅速上升,触发保护动作,保护出口闭锁阀组。并提出对换流变压器进线CVT进行全面排查等建议。Three sets of valves at the low end of the pole Ⅰ of Zalut converter station protect the host converter transformer overvoltage protection action,resulting in the blocking of the end valve group of Zalut DC line pole Ⅰ of low end.The U-phase secondary cable and CVT body of the outlet line of pole Ⅰ low end converter transformer are inspected on site,and the damage is found in the cable sheath.Through onsite inspection,analysis and verification,it is determined that the reason is that there are two instantaneous short circuits in the secondary circuit,which makes the CVT excited twice ferroresonance in a very short time.The energy generated by the first ferromagnetic resonance has not been eliminated,and the superposition of the energy generated by the second ferromagnetic resonance leads to a rapid rise in the amplitude of the resonance recovery overvoltage,which triggers the protection action and protects the outlet locking valve set.Suggestions are put forward for comprehensive investigation of incoming CVT of converter transformer.

关 键 词：CVT 二次回路 分频谐振 过电压保护 阀组闭锁 

分 类 号：TM45P.2[电气工程—电器]