Research On VFTO Waveform And Suppressing Method With Magnetic-rings

VFTO waveform is affected by the operation mode, the position of the disconnector and the structural parameters of the substation. The VFTO waveforms change greatly under different operating modes. It is necessary to analyze the characteristics of the VFTO waveforms when operating different disconnectors in different operating modes, to use the magnetic rings to suppress the VFTO need to establish the simulation model of the magnetic ring, and the application of magnetic ring in substation should be studied.In this paper, the simulation model of GIS components is built by using EMTP software. The simulation circuit is simulated in 252kV Zhanjiang substation. After comparing the VFTO waveforms on the power supply side and the load side under various operating modes, the load side waveform is selected as the typical waveform and the four operation modes of the GIS isolation switch operation are summarized. The characteristic parameters of VFTO waveforms generated by the operation of 500kV Houziyan and 750kV Xishan substation in different operation mode are analyzed and the rules of VFTO waveform are summarized. The bus length of power supply side and load side of isolation switch on the impact of VFTO is also analyzed.In order to study the characteristics of the suppressing method with magnetic-rings, the application characteristics and main characteristics of different magnetic materials are analyzed,and the parameter calculation method of magnetic ring equivalent model is established by combining with the properties of magnetic ring materials. The attenuated VFTO waveforms obtained by this method are compared with the experimental results. The simulation results are in good agreement with the experimental results.The simulation model of 1000kV Fuzhou substation is built. Based on this, the influence of magnetic rings' position on the suppression effect is studied. The VFTO amplitude is attenuated by 26.8% when the equivalent resistance is 250 ohm and the inductance is 0.02mH, the VFTO amplitude is reduced by 23.5%when the magnetic ring is installed between the arrester and the busbar.When the magnetic ring is installed on the load side of the disconnector and in the vicinity of the arrester, the equivalent resistance of the load side magnetic ring of the disconnector is reduced to 60 ohms, and the amplitude is suppressed by 46.6%.