各向异性非线性直流电场数值算法研究

The Study on Numerical Method for Anisotropic Nonlinear DC Electric Field

油纸复合绝缘中的直流电场与交流电场在数值算法上有很大不同，其中油浸纸的层叠结构使其电导率呈各向异性。本文应用Ｇａｌｅｒｋｉｎ法建立了各向异性直流电场的有限元模型，通过一个算例验证了模型的正确性；针对材料的非线性特征，给出了合理的收敛判据和松驰因子；最后应用所建模型计算了一种典型的换流变压器绕组端部绝缘中的直流电场的分布，并与线性各向同性、非线性各向同性电场的计算结果进行了比较，所得结论与已有的试验结论一致。

Numerical computation of DC electric field in oil immersed paper insulation is quite different from that of AC electric field.Due to its laminated structure,The conductivity of the oil immersed paper is anisotropic.A new finite element model based on Galerkin`s method is established and verified by a simple numerical example.A reasonable choice of relaxation factor and convergence criteria for solving the nonlinear electric filed is given.The developed model is employed to compute the DC lelectric field distribution in the typical winding end insulation of a converter transformer.The calculated results are compared with those of linear,isotropic electric field and nonlinear,isotropic electric field.Derived conclusions are in goog agreement with test results.