Reseairch On The Influence Of Arc Disconnector Model And Other Parameters On VFTO In GIS Equipment

Gas-insulated substation,or GIS for short,have a wide range of applications and are an important part of the power system.Isolating switches in GIS generate extra-fast transient overvoltage(VFTO)with high amplitude and steep wavefronts during operation.VFTO will greatly threaten the insulation level of the primary electrical equipment and the safety and stability of the electrical secondary equipment.The arc model,the size of the isolating switch bus,the parameters of the pot insulator and the initial value distribution and setting all have a great influence on the theoretical analysis of VFTO.Based on the measured arc equivalent resistance,two different simulation softwares are used to simulate the three-dimensional transient electromagnetic field model and the one-dimensional simulation model respectively and verify each other.First of all,based on the vector dynamics simulation,the influence of the initial value of the electric field on the VFTO is analyzed and the initial value most suitable to the actual situation is selected.Then the influence of the distribution of the electric charge on the VFTO is analyzed and calculated.The nonuniform distribution of charges is more in line with the actual operation.In this paper,the initial value and the nonuniform distribution of charge are used to further simulate.Secondly,based on the measured arc equivalent resistance,the simulation of this paper is based on the 3-D electromagnetic analysis,the use of conductive medium to establish the arc model,this model is consistent with the actual.The effects of different pot insulator models,different radii of cylindrical arc model,different GIS shell sizes and Vibrating Waveform bus bars on VFTO waveforms were analyzed by two software simulations.Finally,VFTO waveforms and peaks at power supply side,arc side and no-load side are analyzed and compared under different arc model radii and GIS shell sizes.When the radius of the arc model drops to a certain value,the value of the radius begins to exert a relatively large influence on the VFTO distribution.The effect is that the size of the radius obviously affects the magnitude of the voltage amplitude at the arc.Therefore,in the analysis of the 3-D electromagnetic field model,you should try to make the radius of the arc model and the actual match.For a compact GIS,the length of the bus from the power side to the side of the arc has an effect on the VFTO waveform.If the length of the pipe is longer,the amplitude of transient overvoltage is greater.