柔性直流背靠背换流站子模块炸裂故障分析

Analysis on Submodule Burst of Flexible DC Back-to-Back Converter Station

为了研究某±420 kV柔性直流背靠背换流站子模块炸裂事故的原因,避免此类事故再次发生,通过现场检查、录波分析和返厂解体分析等手段,获取了较多的支撑原因的证据。研究表明:在换流阀不控充电过程中出现的子模块上行通信故障会导致黑模块的产生,黑模块导致子模块不可控,旁路开关无法合闸将其旁路,解锁后子模块持续充电,在有源钳位的功能下最终引起了上、下管直通放电,导致子模块炸裂。

In order to study the cause of the submodule burst accident of a ±420 kV flexible DC back-to-back converter station and avoid the recurrence of such accidents,this paper uses the approach of field inspection,recorded wave analysis and return-to-factory disassembly analysis to obtain a lot of evidences supporting the cause.The research results are shown as follows:The uplink communication failure of the submodule during the process of non-controlled charging of the converter valve will result in the generation of black modules. The black module causes the submodule to be uncontrollable,and the bypass switch fails to close and bypass the submodule. After unlocking the submodule,it keeps charging,and finally causes the direct discharge of the upper and lower tubes under the function of the active clamp,resulting in the bursting of the submodule.