高压直流换流变压器阀侧非线性电场的求解

为研究换流变压器阀侧绕组端部的高度非线性直流电场,经理论分析建立了非线性电场的有限元计算模型。针对绝缘材料的非线性特征应用所建模型通过迭代求解,获得了工程关心部位的电场强度分布。计算一种典型的换流变压器绕组端部绝缘中直流电场分布的结果表明,绝缘纸板、变压器油中的最高场强值均变小,尤其是绝缘纸板中最大单元场强明显降低,这个变化趋势对绝缘结构设计非常有益。

Solution to Nonlinear Electric Field of HVDC at Ends of Valve-side Winding in Converter Transformer

To study the serious nonlinearity of electric field at ends of valve-side winding in converter transformer HVDC,this paper presents and develops a finite element method calculation model for nonlinear electric field based on theoretical analyses.Considering the nonlinearity of the insulation materials,the validity of the FEM model 1s proved with iterative solution by illustration examples,the electric field intensity at the part concerned by engineer is obtained as a result.Finally,the FEM model is employed to calculate the DC electric field distribution in a typical insulation structure of Valve-Side Winding in Converter Transformer.The results show that the maximum electric field intensity among the elements in both the insulation papers and transformer oil have drops down obviously,especially in the insulation papers which are very beneficial for the design of the insulation structure.This change tendency indicates that the traditional calculation method for the electric field is conservative and the insulation design is forced to be more difficult and complicated,meanwhile the FEM nonlinear calculation method can provide a theoretical guide for the insulation design and manufacture.