极性反转条件下基于双极性载流子-离子混合输运模型的XLPE空间电荷特性研究

Study on space charge characteristics of XLPE under polarity reversal based on bipolar carrier-ion mixed transport model

直流电缆在运行时需承受极性反转的电压,这会使得绝缘内部积累的空间电荷增加,进而可能引起绝缘破坏。同时在绝缘材料实际生产过程中引入的交联副产物等杂质解离产生的离子电荷会加剧电荷的积累。因此本文对传统双极性载流子输运模型进行改进,考虑杂质带电离子的影响,利用改进后的输运模型模拟交联聚乙烯(XLPE)内部空间电荷在电压极性反转期间的分布,研究极性反转时间和电场强度对电荷分布的影响机理。结果表明:在满足电压反转前后空间电荷分布基本呈镜像分布的基础上,引入离子电荷会增大两电极附近稳态时积聚的异极性电荷量;电压反转时间越长,两电极处的界面电荷峰值下降的越多,两电极附近的空间电荷变成相反极性的电荷量也越多,即反转完成时电荷分布更接近于反转稳定后的情况;在相同极性反转时间、不同电场强度下,电荷分布规律基本相同,场强越高,各处积累的电荷量越多。

During the operation of DC cable,the polarity reversal of voltage increases the space charge accumulated in the insulation,and it may damage the insulation.At the same time,the ionic charge generated by the dissociation of impurities such as cross-linking by-products introduced in the actual production process of insulating materials will aggravate the charge accumulation.Therefore,the traditional bipolar carrier transport model was improved in this paper.Considering the influence of impurity charged ions,the distribution of space charge in XLPE during the polarity reversal of voltage were simulated by using the improved transport model,and the influence mechanism of polarity reversal time and electric field intensity on charge distribution was studied.The results show that,on the basis of satisfying the mirror image distribution of space charge before and after the polarity reversal of voltage,the introduction of ionic charge increases the amount of heteropolar charge accumulated near the two electrodes in the steady state.Under the same polarity reversal time and different electric field intensity,the charge distribution law is basically the same,the higher the field strength,the more charge accumulates everywhere.