基于密度泛函理论的外电场下高能辐照XLPE分子结构特性研究  

Research on XLPE Molecular Structure Characteristic of High-energy Radiation under the External Electric Field Based on Density Functional Theory

作　　者：张峻伟 ZHANG Jun-wei(The UHV Branch Company State Grid Fujian Power Co.Ltd.,Fuzhou 350000,China)

机构地区：[1]国网福建省电力有限公司超高压分公司,福建福州350000

出　　处：《电气开关》2022年第6期74-79,共6页Electric Switchgear

摘　　要：交联聚乙烯(XLPE)凭借其优越的电气性能、机械性能和耐热性被广泛运用于各电压等级的电力电缆中。但其故障率也在逐年提高,很大程度上影响了电力系统的安全稳定运行。交联聚乙烯的材料老化是其绝缘性能降低的主要原因,老化始于内部,分子空间电荷的改变最终影响分子结构的变化。低电场强度下,分子整体构型改变不大。对比无电场在突加电场时XLPE分子交联点处碳的原子所带正电荷,且电荷量上升。但随着场强的增加,分子体系总能量下降,ΔELUMO-HOMO差值也随之下降。当场强达到Field=X+200时出现拐点,交联点所带电荷突然升高,ΔELUMO-HOMO能隙差骤降,分子构型也扭曲变形。此时XLPE可能发生电树枝老化。当场强达到Field=X+400时,分子发生首次碳氢断键,XLPE分子可能被绝缘击穿。若场强再次增加到Field=X+800时,XLPE将会发生解裂,伴随着大量H离子及自由基的形成。此拐点对于XLPE电缆的状态评估和剩余寿命的预测有重要意义。Cross-linked polyethylene are widely used in the voltage level of the power c-able with its superior, electrical properties, mechanical properties and heat resistance.However, the failure rate was gradually increased, largely affected the safe and st-able operation of the power system, XLPE insulation material aging is the main reason for performance degradation, aging begins inside, and the change of molecular space charge will change the structure of molecules.Under the low field strength, the overall configuration of the molecule changed little.In contrast to the absence of an electric field applied electric field when suddenly inter molecular cross linking point XLPE carbon atoms positive charges, and the amount of charge on the rise.However, with the increase of the field strength, the total energy of molecular systems decrease, XLPE high electric field is applied on the spot intensity reaches Field=X+200 inflection point occurs.When the field strength reaches Field=X+400,the first hydrocarbon molecules bond breaking, If the field strength is increased to Field=X+800,XLPE disintegration will occur, with the formation of a large number of H ions and free radicals.The turning point for the state assessment XLPE cable and remaining life prediction is important.

关 键 词：XLPE分子 电场强度 电荷分布 分子能量 

分 类 号：TM215[一般工业技术—材料科学与工程]