The calculate of nonlinear and anisotropic electric field in valve side winding of converter transformer

Oil-immersed insulating material has an anisotropic and nonlinear conductivity, so the direct current (dc) electric field calculation should take these factors into consideration. In this paper, a new calculating method based on ANSYS secondary development technology is proposed. Then, the nonlinear and anisotropic dc electric field is calculated, considering electrical stress and temperature impact on conductivity. The results show that the electric field distribution calculation is very different if considering or not considering these factors. Therefore, the converter transformer insulation design should be calculate as anisotropic and nonlinear field.