棒-板油纸复合绝缘的电场数值计算

Numerical Computation of Electric Field of Rod-plane Oil-paper Insulation

换流变压器阀侧绕组端部属极不均匀场,承受交流电压、直流电压及极性反转等电压的作用。为此采用有限元仿真软件对棒-板油纸复合绝缘极不均匀场模型在不同参数情况时的直流场强分布、交流场强分布及极性反转场强分布进行了计算,绘制了绝缘油及绝缘纸板中最大场强与绝缘纸板厚度、纸板长度、棒直径等参数的关系曲线。棒-板油纸复合绝缘模型在交流电压及极性反转电压作用下的场强分布较为接近,但与直流电压下的场强分布有很大的不同。通过提高换流变压器阀侧绕组端部等效棒直径及油的电阻率,选择合理的油与纸空间相对位置及几何尺寸,可比较明显地提高换流变压器阀侧绕组绝缘特性。

The electric field at the valve-winding end of converter transformer is totally nonuniform. The valve-winding of converter transformer withstands not only AC voltage, but also DC voltage and polarity reversal（PR） voltage, which is a special phenomenon occurring during operation of a converter transformer. By finite element method （FEM）, this paper concentrates on calculating electric field distribution on rod-plane oil-paper insulation. It is drawn that the curves of the maximum electric field in pressboard and oil with the pressboard thickness, the ratio of oil conductivity to paper conductivity, duration time of PR and so on. The electric field distribution of rod-plane oil-paper insulation under AC voltage is approximate to that under PR voltage, however, it is very different to that under DC voltage. The insulating properties of converter transformer valve winding end can be improved obviously by a larger the equivalent bar diameter of converter transformer valve winding end , a bigger resistivity of oil and a proper size and position of oil and paper.