混合电场作用下换流变压器阀侧绕组电场分析

为了计算换流变压器阀侧绕组端部电场分布,建立了油纸复合绝缘结构的电路模型。并在分析阀侧绕组励磁电压类型的基础上,利用有限元分析法计算了在交流、直流、交直流叠加和极性反转电压作用下的电场分布,总结了电场分布规律。结果表明,换流变压器阀侧绕组电场分布既有其规律性又有其复杂性,在直流电场作用下的阻性电场分布将导致纸板中的电场集中;而交流电场作用下的容性电场分布将导致变压器油中的电场集中;在极性反转过程中由于空间电荷的存在,油中承担了较高的电压。该分析结果可为换流变压器阀侧绕组端部的绝缘设计提供依据。

Analysis of Complex Electrical Field on Valve Side Winding of Converter Transformer

In order to analyze the electrical field distribution of the converter transformer,the simulation model of oil-paper combination is established,and the maximal field intensity positions of the insulation under different excited voltages such as DC field,AC field,superimposed AC-DC field and a polarity reversal voltage are emulated with FEM(Finite Element Method).The distinguishing features of the transient field are summarized,and the calculation results show that the characteristics of electric field at valve side winding of converter transformer are both regularity and complexity.The electric field's distribution under the DC voltage is depended on the resistivity,which leads to the higher electric-field intensity in the insulating carboard.And the electrical field distribution under AC voltages is depended on the dielectric constant,which leads to the higher electrical field intensity in the oil.Under the polarity reversal voltage,the oil will undertake a very high voltage caused by the space charge accumulation.