架空线对GIS变电站VFTO抑制效果的分析

VFTO inhibitory effect analysis of overhead line in GIS substation

针对GIS变电站开关操作产生快速暂态过电压（VFTO）的抑制问题,基于电磁暂态仿真软件ATP-EMTP搭建的仿真模型,提出采用架空线来连接GIS母线出口套管和主变压器的思路,利用架空线单位长度内几何电感较大,以及考虑架空线产生电晕等影响因素来削弱VFTO的幅值和波头陡度,保护主变压器的安全运行。通过搭建ATP-EMTP仿真模型,分别采用1~45 m架空线连接GIS母线出口套管和主变压器,仿真计算得到入口处的VFTO波形。仿真结果表明：架设20 m左右架空线就能够把变压器入口处的VFTO波头陡度降到允许值范围内,具有一定的工程实用价值。

In order to suppress the very fast transient overvoltage （VFTO）caused by switching operation in GIS substation,a simulation model based on electromagnetic transient simulation software ATP-EMTP was built,and a VFTO suppression method which used overhead line to connect GIS output bus bushing and main transformer was also proposed.Owing to the larger ge-ometrical inductance in overhead line per unit length and the corona of overhead line,VFTO am-plitude and wave-head steepness were suppressed,and the safe operation of GIS substation was guaranteed.Simulation results showed that,with about 20 m overhead line,the VFTO wave-head steepness could be suppressed in the allowed range.The suppression method has a great practical application value.