Using of surrogate models of electrophysical characteristics for the design of high-voltage insulators, taking into account the potential presence of defects

The article is devoted to the construction of surrogate models as a tool for assessing the influence of the properties of materials of insulating structures and the defects present in them, the geometry of insulating structures, on the electrical strength in the area of the defect location. Using the example of a glass part of the PS-70E (U70) insulator, it is shown that a surrogate model in the form of a polynomial of four seventh-order variables, which takes into account changes in the dielectric permittivity and specific conductivities of the model materials, is sufficient to analyze the electrical strength in the area of the defect location when the properties of materials change. The relative error in determining the electric field based on the results of simulation modeling and calculation using the surrogate model is no more than 11.2 % and 10.7 % for the maximum and minimum electric field strengths in the defect, respectively. It is shown that the dielectric constant of the substance of the insulating structure has a significant effect on the field strength only when the permeability of the defect substance is less than 6, which is typical for defects in the form of gas inclusions. The change in the characteristics of the field in the defect, depending on the geometry of the structure, was also considered using the example of the head of the glass part of the PS-70E insulator. The change in geometry was studied at different values of the amplitudes of the first spatial harmonics of the forming boundaries with a simultaneous change in the location of the spherical defect inside the structure. It is shown that in this case, a polynomial of 5 degrees of 4 variables is sufficient to construct a surrogate model. The maximum margin of error is no more than 7.6 %. The analysis of the dependences of the field strengths inside the defect in the considered surrogate models, as well as in the obtained model, suggests that defects in high-voltage insulators ranging in size from 0.1 to 2 mm can be considered potentially dangerous.