| The ice surface flashover in high-voltage transmission line is partly caused by the ice on the surface of the insulator and will have a diverse impact on the reliability of grid. Therefore, it is necessary to study the characteristics of flashover of ice insulator covered with ice. In china, studies on insulator covered with ice are mainly concentrated on the field test and flashover mechanism of flashover of the insulator covered with ice studied by this paper will provide a theoretical basis for engineering tests.Under the setting of manual boundary condition, electric field control equation of 220kV insulators covered with ice has been soluted by finite element method and got the distribution of electric field and potential and relevant physical parameters of the surface of insulators under high voltage, such as the length of icicles, continuity, length of gap and the situation of ice. It is indicated that The results have showed that the ice caused by electric field and potential distribution of insulator surface distortion, in particular, when the insulator sheds ice completely covered bridge, the maximum electric field and potential distortion. Icicles the same length, location of the air gap is not the same distortion of electric field and potential are also different. The presence of high electrical conductivity of water film, the ice near a body of such potential, further increase the air gap on the pressure drop. The maximum field intensity appears in the head of arc caused by the emergence of arc. But the maximum of arc in high end and low end are difference, about 41.5 kV cm and 17.5 kV cm, respectively.This paper built AC and DC discharge model by MATLAB based on Obenaus concept and simulated the change of arc with time under AC and DC voltage. The simulation results are fully in line with the results of field tests. Therefore, it is indicated that the model is correct. |
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