纳米改性复合液体硅橡胶电导率及直流击穿特性研究

发布时间：2018-02-28 20:01

本文关键词： 高压直流电缆附件纳米复合硅橡胶电导率直流击穿场强温度掺杂浓度　出处：《哈尔滨理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：作为高压直流输电系统中不可或缺的一部分，高压直流电缆在运行中不仅要承受额定直流电压，还需承受极性反转电压、雷电冲击电压和操作冲击电压的作用，而电缆附件更是由于其复杂的绝缘结构和复合绝缘成为电缆绝缘中最为关键和薄弱的环节。为解决高压直流下，电缆附件内复合绝缘因电导率差异引起的电场分布不均问题，本文通过对附件绝缘液体硅橡胶(LSR)进行纳米改性，使其电导率在不同温度和电场强度下均能与电缆本体绝缘交联聚乙烯电导率良好匹配，实现电场分布的均化。根据硅橡胶试样的制备工艺流程，本文以双组份加成型液体硅橡胶为基料，纳米氧化镁(MgO)和纳米碳化硅(SiC)为改性填料，在实验室制备了不同掺杂浓度的纳米复合液体硅橡胶试样和纯硅橡胶试样。在此基础上，分别对其电导率和直流击穿强度进行了测量与比较，并且研究分析了不同纳米掺杂浓度、温度和电场强度对电导率特性及直流击穿特性的影响。最后，通过电场仿真分析，验证了纳米改性前后复合液体硅橡胶下高压直流电缆附件内电场分布的均匀情况。实验结果表明，与纯液体硅橡胶相比，MgO/LSR纳米复合材料的电导率几乎没变，而SiC/LSR纳米复合材料的电导率有了明显的改善提高。MgO/LSR纳米复合材料的直流击穿强度先缓慢下降后突然上升，而SiC/LSR纳米复合材料先小幅上升后逐渐下降，与纯硅橡胶相比，均差别大不。通过仿真结果发现，纳米复合氧化镁/硅橡胶下的电缆附件内电场分布依旧不均匀，而纳米复合碳化硅/硅橡胶下的电缆附件内电场分布相对均匀，表明纳米氧化镁的掺杂改性无法实现电缆附件内的电场均化，而纳米碳化硅的掺杂改性使得纳米复合碳化硅/硅橡胶能与交联聚乙烯电导率良好匹配，并且实现电缆附件内的电场分布均化。
[Abstract]:As an indispensable part of HVDC transmission system, HVDC cable not only bears rated DC voltage, but also bears the effects of polarity reversal voltage, lightning impulse voltage and operating impulse voltage. Cable accessories are the most important and weak link in cable insulation because of their complex insulation structure and composite insulation. In order to solve the problem of uneven distribution of electric field caused by the difference of electrical conductivity in cable accessories under high voltage DC, In this paper, through the nano-modification of LSRs, the conductivity of LSRs can match well with the conductivities of XLPE at different temperature and electric field strength, and the electric field distribution can be homogenized. According to the technological process of preparation of silicone rubber sample, in this paper, two-component additive liquid silicone rubber was used as base material, and nano-MgO and sic _ 3 were used as the modified fillers. Nano-composite liquid silicone rubber samples with different doping concentrations and pure silicone rubber samples were prepared in laboratory. The electrical conductivity and DC breakdown strength were measured and compared respectively. The effects of different nanocrystalline doping concentration, temperature and electric field intensity on the conductivity and DC breakdown characteristics are studied. Finally, the electric field simulation analysis is carried out. The uniformity of electric field distribution in the attachment of HVDC cable before and after nano-modification was verified. The results show that the conductivity of MgO / LSR nanocomposites is almost the same as that of pure liquid silicone rubber. The electrical conductivity of SiC/LSR nanocomposites was improved obviously. The DC breakdown strength of MGO / LSR nanocomposites decreased slowly and then increased suddenly, while that of SiC/LSR nanocomposites increased slightly and then decreased gradually, compared with pure silicone rubber, the DC breakdown strength of MGO / LSR nanocomposites decreased gradually. The simulation results show that the electric field distribution in the cable accessory is still uneven, while the electric field distribution in the cable accessory under nano-composite silicon carbide / silicone rubber is relatively uniform. The results show that the doping modification of nano-MgO can not achieve the electric field homogenization in the cable accessory, while the doping modification of nano-silicon carbide can make the nano-composite sic / silicone rubber match well with the conductivity of crosslinked polyethylene. And the electric field distribution in the cable accessory is homogenized.
【学位授予单位】：哈尔滨理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM215.2

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