| For the requirement of miniaturization and insulation properties of high voltage and extra high voltage switchgear, three dimensional electric field analysis model of 40.5kV/SF6 C-GIS circuit breaker is analyzed and calculated. Three dimensional electric field of large size 1100kV GIS disconnector cabinet is analyzed and calculated. Transient electric field of 1100kV GIS insulator surface is analyzed and calculated. So electric field distribution of switchgear can be predicted more exactly, then the level of insulation can be improved.Firstly, three dimensional electric field analysis model of 40.5kV/SF6 C-GIS circuit breaker is analyzed and calculated. For the complexity of actual product structure, the model was meshed by using the parameter settings and sparse and dense meshes of the grid dividing control tool, and the regions of complex structure are rebuilt for amplifying dangerous regions and improving the precision of electric filed calculation. According to the analysis result, the positions of maximum electric field strength each area and the intensity values are obtained. Then more theory reference can be provided for the design of insulation structure.Secondly, three dimensional electric field of 1100kV GIS disconnector cabinet is analyzed and calculated. The dimension of 1100kV disconnector cabinet in GIS is seven times larger as of the dimension of circuit breaker, and the shapes of electrodes are complex. This paper compiles program for calculating the three dimensional electric field with using region decomposition method and present software. The distributions of electric field intensity and the curves of electric field intensity distributions in different electrode surfaces are acquired. Then the positions of maximum electric field strength each area and their intensity values are obtained according to the result analysis. The effects on the electric field distribution near the surface of contact caused by change of dimensions of earthing switch static contact diameter and boundary chamfer are analyzed. The capacitance parameters are calculated by using electric field energy method, then the calculation results of capacitance in different positions of disconnector cabinet are acquired, and the calculation results of capacitance parameters are compared with the test results of capacitance parameters.Finally, VFTO is generated when disconnector divide and close bus-bar capacitance current in GIS which has the feature of short rise time and high amplitude. The insulator surface is more dangerous on the effect of VFTO under the working air pressure than on the effect of lightning surge. The insulator surface is more dangerous on the effect of VFTO under the working air pressure than on the effect of lightning surge. Therefore the distribution of electric field intensity along insulator surface caused by VFTO is analyzed in this paper. Primarily the result of numerical simulation is treated by fourier transform method, then the result of numerical simulation is fitted used least-squares procedure. The fitting curve of transient waveform which caused by VFTO is obtained, then the proportion factor of various frequency in the whole is obtained. The frequency-domain mathematic model for calculating transient electric field can be deduced and the potential distribution considering the nonlinear of dielectric constant and various frequency component. Electric field intensity distribution, electric filed intensity tangential component and normal component distribution of insulator and around it caused by VFTO can be calculated, thus the insulating property of insulator can be further analyzed. |
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