外电场对硅烷交联聚乙烯电介质材料分子空间结构影响的分子模拟研究
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摘要
为了从分子层面上揭示外电场作用下硅烷交联聚乙烯电缆材料内部分子结构特性的变化情况,采用计算量子化学模拟方法构建硅烷交联聚乙烯分子模型。沿聚乙烯主链方向施加不同大小的电场,分析硅烷交联聚乙烯分子的稳态总能量、偶极矩、分子极化率、电荷分布、能隙和红外光谱变化规律。结果表明:随着电场强度的增大,硅烷交联聚乙烯分子结构发生明显变化。当电场强度达到一定值后,分子稳定结构遭到破坏进而出现断键现象。硅烷交联聚乙烯分子在强电场作用下,主链两端的C-C键和C-H键最先断裂形成自由基。分子内部电荷在电场作用下发生转移,使得聚乙烯链端部C、H原子带电量最大且不断增加,最终导致断键后的C、H自由基带有较高电荷量。这些游离的自由基会形成空间电荷,外电场越大,空间电荷量越大。这些电介质内部微观特性的变化对研究交联聚乙烯电缆的电树枝老化机理具有重要意义。
In order to reveal the internal molecular structural property changes of silane crosslinked polyethylene(XLPE) cable material under external electric field at molecular level, a molecular model of silane XLPE was built by computational quantum chemical simulation method. Different intensities of electric field were applied along the main chain of polyethylene, and then the change law of the steady-state total energy, dipole moment, molecular polarizability, charge distribution, energy gap, and infrared spectrum of the silane XLPE were analyzed. The results show that the molecular structure of silane XLPE has obvious change with the increase of electric field intensity. When the electric field intensity reaches to a certain value, the stable molecular structure is destroyed and the bonds break. Under high electric field, the C-C bonds and C-H bonds at the both ends of silane XLPE main chain break at first.and then form free radicals The intramolecular charge would transfer under the effect of electric field, results in the C and H atoms at the ends of polyethylene chain have the largest charge which increase continuously, and finally the C and H free radicals have higher charges after bond breaking. The free radicals would form space charge, and the amount of space charge increases with the increase of external electric field. These resluts have great significance to study the mechanism of electrical tree ageing in XLPE cables.
In order to reveal the internal molecular structural property changes of silane crosslinked polyethylene(XLPE) cable material under external electric field at molecular level, a molecular model of silane XLPE was built by computational quantum chemical simulation method. Different intensities of electric field were applied along the main chain of polyethylene, and then the change law of the steady-state total energy, dipole moment, molecular polarizability, charge distribution, energy gap, and infrared spectrum of the silane XLPE were analyzed. The results show that the molecular structure of silane XLPE has obvious change with the increase of electric field intensity. When the electric field intensity reaches to a certain value, the stable molecular structure is destroyed and the bonds break. Under high electric field, the C-C bonds and C-H bonds at the both ends of silane XLPE main chain break at first.and then form free radicals The intramolecular charge would transfer under the effect of electric field, results in the C and H atoms at the ends of polyethylene chain have the largest charge which increase continuously, and finally the C and H free radicals have higher charges after bond breaking. The free radicals would form space charge, and the amount of space charge increases with the increase of external electric field. These resluts have great significance to study the mechanism of electrical tree ageing in XLPE cables.
引文
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[18]廖瑞金,郝建,梁帅伟,等.水分和酸对矿物油与天然酯混合油-纸绝缘热老化的影响[J].电工技术学报,2010,25(7):31-37.
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[20] HUANG Y L, MERKER T, HEILIG M, et al. Molecular modeling and simulation of vapor-liquid equilibria of ethylene oxide, ethylene glycol, and water as well as their binary mixtures[J]. Industrial&Engineering Chemistry Research,2012,51(21):7428-7440.
[21]王学磊,李庆民,张颖,等.变压器油高温裂解及油中酸影响机理的反应分子动力学模拟[J].高电压技术,2017,43(1):247-255.
[22]廖瑞金,胡舰,杨丽君,等.变压器绝缘纸热老化降解微观机理的分子模拟研究[J].高电压技术,2009,35(7):1565-1570.
[23]马岩.硅烷交联聚乙烯电缆材料的制备与反应动力学研究[D].哈尔滨:哈尔滨工业大学,2006.
[24]蔡绍洪,周业宏,何建勇.外场下丙烯酸甲酯的激发特性研究[J].物理学报,2011,60(9):233-240.
[25]刘晓东,郑晓泉,屠德民,等.交联工艺对交联聚乙烯中空间电荷的影响[J].绝缘材料,2005,38(5):23-27.
[2]朱晓辉,孟峥峥,王浩鸣,等.运行高压交联聚乙烯电力电缆的介电性能[J].高电压技术,2015,41(4):1090-1095.
[3]姚海燕,张静,留毅,等.基于多尺度小波判据和时频特征关联的电缆早期故障检测和识别方法[J].电力系统保护与控制,2015,43(9):115-123.
[4]夏向阳,张琦,李明德,等.证据理论与模糊理论集成的XLPE电缆绝缘状态评估研究[J].电力系统保护与控制,2014,42(20):13-18.
[5]孙仲民,何正友,戴铭.基于灰色预测的电力电缆老化过程预警仿真研究[J].电力系统保护与控制,2012,40(13):55-60.
[6]李伟,任志刚,刘弘景,等.电缆中间接头硅橡胶电树枝生长与形貌特性研究[J].电力系统及其自动化学报,2017,29(6):78-82.
[7]王霞,孙晓彤,刘全宇,等.基于空间电荷效应的绝缘老化寿命模型的研究进展[J].高电压技术,2016,42(3):861-867.
[8]陈向荣,徐阳,刘英,等.交联聚乙烯电缆绝缘材料中电树枝的导电特性研究[J].物理学报,2012,61(8):416-425.
[9] FUKUDA T. Technological progress in high voltage XLPE power cable in japan[J]. IEEE Electrical Insulation Magazine,1998,4(6):15-20.
[10]杜伯学,苏金刚,徐航,等.机械应力下高温硫化硅橡胶电树枝生长特性[J].中国电机工程学报,2016,36(24):6627-6634,6915.
[11]周利军,仇祺沛,成睿,等.不同温度下局部气压对XLPE电缆电树枝生长及局放特性的影响[J].中国电机工程学报,2016,36(18):5094-5102,5135.
[12] ZHANG Ling, ZHOU Yuanxiang, TENG Chenyuan, et al.Effect of epitaxial crystallization on packet-like space charge characteristics in low-density polyethylene under multi-field coupling conditions[J]. Journal of Electrostatics,2017,88:88-93.
[13] MAMMERIC M, LAURENT C, SALON J. Influence of space charge build up on the transition to electrical treeing in PE under AC voltage[J]. IEEE Transactions on Dielectrics and Electrical Insulation,1995,2(1):27-35.
[14]刘刚,谢月,杨婉琪,等.高压退役电缆空间电荷特性[J].高电压技术,2016,42(11):3607-3615.
[15]陈广辉,王安妮,何东欣,等.交联聚乙烯绝缘空间电荷研究进展[J].绝缘材料,2012,45(4):27-40.
[16]李庆民,黄旭炜,刘涛,等.分子模拟技术在高电压绝缘领域的应用进展[J].电工技术学报,2016(12):1-13.
[17]廖瑞金,吴伟强,聂仕军,等.复合热稳定剂对绝缘纸协同抗老化效应的分子模拟研究[J].电工技术学报,2015,30(10):330-337.
[18]廖瑞金,郝建,梁帅伟,等.水分和酸对矿物油与天然酯混合油-纸绝缘热老化的影响[J].电工技术学报,2010,25(7):31-37.
[19] YOUNKER J M, SUNKARA H B, BENDLER H V, et al. Prediction of flex modulus and solubility parameters for environmentally friendly nylon plasticizers by molecular dynamics simulations[C]//248th National Meeting of the American-Chemical-Society.2014:248.
[20] HUANG Y L, MERKER T, HEILIG M, et al. Molecular modeling and simulation of vapor-liquid equilibria of ethylene oxide, ethylene glycol, and water as well as their binary mixtures[J]. Industrial&Engineering Chemistry Research,2012,51(21):7428-7440.
[21]王学磊,李庆民,张颖,等.变压器油高温裂解及油中酸影响机理的反应分子动力学模拟[J].高电压技术,2017,43(1):247-255.
[22]廖瑞金,胡舰,杨丽君,等.变压器绝缘纸热老化降解微观机理的分子模拟研究[J].高电压技术,2009,35(7):1565-1570.
[23]马岩.硅烷交联聚乙烯电缆材料的制备与反应动力学研究[D].哈尔滨:哈尔滨工业大学,2006.
[24]蔡绍洪,周业宏,何建勇.外场下丙烯酸甲酯的激发特性研究[J].物理学报,2011,60(9):233-240.
[25]刘晓东,郑晓泉,屠德民,等.交联工艺对交联聚乙烯中空间电荷的影响[J].绝缘材料,2005,38(5):23-27.