单层油纸绝缘结构合成电场数值计算

Numerical Calculation of Synthetic Electric Field in Single-Layer Oil Paper Insulation Structure

直流电压下换流变压器阀侧油纸绝缘介质中存在空间电荷的积聚,对其结构内部的电场分布造成影响。考虑了异极性空间电荷间的复合以及入陷、脱陷效应,采用有限元法求解泊松方程和电流连续性方程,基于多物理场耦合迭代的思想实现了单层油纸绝缘介质中空间电荷运动特性及瞬态电场分布的动态仿真。考虑系统潮流反转的情况,模拟了电压极性反转条件下油纸绝缘结构内部合成电场的变化过程,计算结果表明:极性反转瞬间,油纸绝缘介质中空间电荷造成的附加影响使得极板处电场强度急剧增高,电场畸变率高达56.3%,严重危及介质绝缘性能,研究内容为换流变压器内绝缘结构优化设计提供了参考依据。

The accumulation of space charges in the oil paper insulation medium on the valve side of the converter transformer under DC voltage affects the electric field distribution inside the structure.This paper considered the recombination of space charges of different polarities and the effects of trapping and de-trapping,used the finite element method to solve the poisson equation and the current continuity equation,and realized the dynamic simulation of space charge motion characteristics and transient electric field distribution in a single-layer oil paper insulation medium based on the coupling of multi-physical field iteration idea.Moreover,it reflected the power flow reversal of the system.In addition,it simulated the change process of the synthetic electric field inside the oil paper insulation structure under the voltage polarity reversal.The result calculation showed that the electric field intensity at the plate increased sharply and the electric field distortion rate was up to 56.3%because of the additional influence space charge in the oil paper insulation.The effect jeopardized the dielectric insulation performance.The re-search provides a reference for the optimization design of the internal insulation structure of the converter transformer.