750kV GIS用变压器端部的快速暂态过电压的研究

GIS内开关操作产生的快速暂态过电压(VFTO)对系统的变压器构成了很大的威胁,对于超高压GIS更是如此。参考多个GIS变电站,建立了750kVGIS系统,并确定了断路器、隔离开关、接地开关及电抗器的计算模型可简化为等值对地电容或入口电容,其参数分别为276pF、240pF、240pF和5000pF。利用EMTP计算了不同操作过程在变压器端部出现的VFTO。分析了系统运行方式、开关操作顺序、变压器入口电容以及变压器与GIS的连接方式对变压器端部VFTO的影响。研究了断路器、隔离开关的并联电阻以及MOA对变压器的保护效果。

Study on the Very Fast Transient Over-voltage at the Transformer Terminals in 750 kV GIS

The operations of CB and DS within GIS will generate VFTO,even for ultra-high voltage GIS,which could endanger the transformer and other equipments.Referring to some GIS substations,the 750 kV GIS system model is set up and the parameters of the system elements are selected.The CB,DS,earthing switch and reactor are simplified as equivalent ground capacitance and entrance capacitance of 276 pF,240 pF,240 pF and 5 000 pF respectively.VFTOs at the transformer terminals at switching processes are calculated by EMTP.The effects of operation modes,switching sequence and the transformer entrance capacitance,as well as the effect of connection of the transformer with GIS on the VFTO at the transformer are analyzed.The protective effects of the shunt resistances of CB?DS and MOA are also studied.