电工技术学报  2024, Vol. 39 Issue (21): 6908-6920    DOI: 10.19595/j.cnki.1000-6753.tces.231759
高电压与放电 |
交联聚乙烯绝缘高温直流击穿威布尔分布的厚度效应
朱敏慧, 闵道敏, 林宋佳, 王诗航
电工材料电气绝缘全国重点实验室(西安交通大学) 西安 710049
Effect of Thickness on DC Breakdown Weibull Distribution of XLPE Insulated Cables at High Temperature
Zhu Minhui, Min Daomin, Lin Songjia, Wang Shihang
State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049 China
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摘要 交联聚乙烯绝缘层厚度设计是高压直流电缆研发的关键任务之一。然而,实验室中难以获得厚绝缘样品的直流击穿性能参数,绝缘层厚度设计缺少直接的数据支撑,因此研究交联聚乙烯绝缘直流击穿的厚度效应具有重要意义。该文获得了不同厚度交联聚乙烯绝缘样品在90℃下的直流击穿特性,揭示了交联聚乙烯绝缘威布尔特征击穿场强和形状参数随样品厚度的增加而减小的厚度效应。采用电荷输运和分子链位移调制模型计算了交联聚乙烯的直流击穿过程,结果表明击穿威布尔形状参数受陷阱能级、陷阱密度、载流子迁移率随机变量标准差的影响。在厚试样中,三种电荷陷阱参数的高斯分布更宽、标准差大,导致击穿场强分散性增大,其中电荷陷阱能级随机变量标准差的影响最显著。因此,交联聚乙烯绝缘电荷陷阱参数分布是决定其高温直流击穿厚度效应的关键。该研究可为高压电缆绝缘设计提供理论指导和实验依据。
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朱敏慧
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关键词 交联聚乙烯厚度效应威布尔分布电荷输运    
Abstract:The design of XLPE insulation thickness is one of the key tasks in the development and manufacturing of HVDC cables. However, it is difficult to obtain the DC breakdown performance parameters of thick insulation samples in the laboratory, and the design of insulation thickness lacks direct data support. Meanwhile, although there are continuous attention and researches on the thickness effect of breakdown field strength and the breakdown Weibull probability distribution of solid dielectric, there are few studies on the DC breakdown field thickness effect based on XLPE at high temperatures, and there are few reports on the dispersion of the DC breakdown field strength. Therefore, it is of great significance to study the effect of thickness on DC breakdown of XLPE insulation. In this paper, the high temperature DC breakdown experiment of XLPE insulation samples with different thicknesses was carried out, and charge transport and molecular displacement modulated model (CTMD) was used to simulate and analyze the breakdown process. Besides, the characteristic breakdown field strength and Weibull distribution shape parameters of XLPE insulation under high temperature DC voltage are studied with sample thickness.
In dielectric insulation, the deep trap captures carriers, forming space charges at the interface of the insulating medium, and the continuous aggregation of space charges make the electric field strength distorted. At the same time, by the Coulomb force, the displacement of the molecular chains make the expansion of the free volume, the charge energy increases dramatically. When the charge energy increases to the point where it can leap over the trap barrier, the insulating material breaks down. DC breakdown experiments were carried out on 160, 300, 400, 550 and 650 μm XLPE specimens at 90℃. The characteristic DC Weibull breakdown field strengths were 264.1, 212.6, 185.0, 147.7, 136.4 kV/mm and the shape parameters of the Weibull distribution were 21.3, 20.5, 19.9, 14.1 and 13.5.
The process of carrier transport and energy accumulation in dielectric insulating materials ultimately leads to the breakdown of the dielectric, and this process is closely related to the charge transport parameters. Therefore, three charge transport random variables, which are trap energy level, trap density and carrier mobility, are introduced into the CTMD model. By adjusting the trap charge transport random variables, the standard deviations of trap energy level, trap density and carrier mobility corresponding to XLPE are obtained.
The following conclusions are obtained from the experiment and simulations: (1) Thick XLPE insulation has a wider Gaussian distribution trap, making the DC breakdown field strength dispersion more obvious. Therefore, the thickness effects of reduced characteristic breakdown strength and increased breakdown strength dispersion need to be considered simultaneously in the design of high-voltage-rated cable insulation. (2) CTMD simulations yield that the shape parameter of the Weibull distribution decreases with increasing standard deviation of the charge transport random variable, and the dispersion of the breakdown field strength data increases. The dispersion of the characteristic Weibull breakdown field strength varies most significantly with increasing standard deviation of the trap energy level. (3) The high-temperature DC breakdown field strength of XLPE insulation decreases with increasing thickness in an inverse power function relationship, and variations in the standard deviation of the charge transport parameter do not affect the characteristic breakdown field strength.
Key wordsXLPE    thickness effect    Weibull distribution    charge transport   
收稿日期: 2023-10-22     
PACS: TM215  
  TM85  
基金资助:国家自然科学基金(52077162, 51777162)和中央高校基本科研业务费专项资金(xzy012019022)资助项目
通讯作者: 闵道敏, 男,1985年生,副教授,博士生导师,研究方向为先进绝缘材料与技术,高储能密度复合电介质,多物理场高效计算,局部放电、击穿、沿面闪络建模仿真与性能提升方法。E-mail:forrestmin@foxmail.com   
作者简介: 朱敏慧, 女,1999年生,硕士研究生,研究方向为交联聚乙烯的介电、击穿性能,交联聚乙烯的多物理仿真特性。E-mail:zzzminhui@stu.xjtu.edu.cn
引用本文:   
朱敏慧, 闵道敏, 林宋佳, 王诗航. 交联聚乙烯绝缘高温直流击穿威布尔分布的厚度效应[J]. 电工技术学报, 2024, 39(21): 6908-6920. Zhu Minhui, Min Daomin, Lin Songjia, Wang Shihang. Effect of Thickness on DC Breakdown Weibull Distribution of XLPE Insulated Cables at High Temperature. Transactions of China Electrotechnical Society, 2024, 39(21): 6908-6920.
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