Simulation Study On Very Fast Transient Overvoltage Of 1000 KV GIS Substation

As ultra-high voltage and UHV transmission technology gradually develop,each substation usually adopts fully enclosed gas insulated substation(GIS,Gas Insulated Switchgear)facilities.There is a very fast transient overvoltage(VFTO),which has characteristics such as large amplitude,high frequency,and less fluctuation time,when the disconnector in GIS is implemented.It leads to some problems associated with the GIS body and electrical insulation safety equipment easily and greatly increases the probability of accidents such as electrical insulation break down.Therefore,it is very important to study the special transient overvoltage in UHV transmission system GIS.This paper mainly studies the generation of VFTO and its influencing factors,and explores several effective measures of suppressing VFTO.In this paper,VFTO generated in GIS substation of 1000kV UHV transmission system is selected as the research object,and the simulation model is established.The waveform generated by VFTO is simulated by ATPDraw.The waveform of closing disconnector by the isolation switch of the GIS is simulated,and the detailed analysis is made.The main factors influencing key equipment as VFTO in GIS are mainly studied,including the inlet capacitance,the branch length of the GIS and the resistance of the switch arc.On the basis of the original simulation model,various factors are changed to simulate results to find out the main factor of influencing VFTO,and then find further effective method of suppressing the VFTO on the basis of the original model to install a variety of suppression measures.The article mainly studies the installation of ferrite magnetic ring,the installation of shock absorbers in the disconnector,and parallel resistance in the transformer.The VFTO waveforms are simulated and analyzed to find out the best suppression measures,so as to effectively reduce the harmfulness of the transient overvoltage in the GIS.This will have a significant impact on the future development of GIS and its related facilities,the stability of the power system and the stable operation of the economy.