特高压直流换流站多柱并联避雷器组局部故障机理研究

Local Fault Mechanism of Multi-Column In-Parallel Surge Arresters in UHV DC Converter Station

特高压直流换流站内的避雷器为了满足能量吸收需求,通常采用多柱并联的结构。但是多柱并联避雷器由于电流及吸收能量不均匀的问题容易发生局部故障,导致系统闭锁。为了明确故障机理,本研究分析了直流换流站内容易发生局部故障的金属回线转换开关(MRTB)避雷器以及中性母线金属回线(EM)避雷器的运行工况及结构特点,研究了不平衡故障的发生过程、故障现象以及解体检查结果,从氧化锌压敏电阻微观结构到避雷器组并联特性总结了局部故障发生的原因、机理,并提出了对应的故障应对措施。

In order to meet the energy absorption requirements,the surge arresters in UHV DC converter stations usually adopt the structure of multi column parallel connection.However,due to the non-uniform current and absorbed energy,multi column parallel surge arresters are prone to local faults,leading to system lockout.In order to clarify the fault mechanism,the author analyzes the operating conditions and structural characteristics of the metal return transfer switch(MRTB)arrester and the neutral bus EM arrester that are prone to local faults in the DC converter station,studies the occurrence process,fault phenomena and troubleshooting results of the unbalanced fault,and summarizes the causes and mechanisms of local faults from the microstructure of zinc oxide varistor to the parallel characteristics of the arrester group.The corresponding countermeasures are proposed.