【作者】 王雅群；

【导师】 尹毅；

【作者基本信息】 上海交通大学 ， 高电压与绝缘技术， 2009， 硕士

【摘要】 直流输电技术由于其在稳定性与经济性等方面的诸多优点,成为目前电气工程领域内研究的热点。高压直流塑料电缆是直流输电的关键设备之一,相对于油纸绝缘直流电缆,具有体积小、输送容量高和免维护等优势,因此研究和开发塑料绝缘直流电缆对直流输电至关重要。然而在塑料绝缘中,由于空间电荷分布不均匀会造成电缆绝缘内电场畸变影响其绝缘强度以及加速绝缘的老化,因此研制塑料绝缘的关键问题是解决绝缘内空间电荷积聚的问题。本文采用电声脉冲法研究聚乙烯及其复合介质内空间电荷分布发现:聚乙烯生产工艺的不同,造成了其内部空间电荷分布的差异。以不同厂家生产的低密度聚乙烯作为基础材料,掺杂相同类型与含量的填料,复合介质内空间电荷分布有较大差别。复合介质的结晶行为影响其内部空间电荷分布,但其对空间电荷的影响小于杂质离子浓度等因素的影响。交联聚乙烯内交联副产物含量对其空间电荷分布影响较大;研究还发现电极材料也是影响XLPE及其复合介质内空间电荷分布的重要因素之一。添加适量的纳米MgO粉末可以有效的改善复合介质内空间电荷分布、击穿特性、电导率和机械性能。利用傅里叶变化红外光谱(FT-IR)与差热分析(DSC)对XLPE与MgO/XLPE纳米复合介质进行研究发现,MgO与XLPE的分子基团之间有相对较强的相互作用。更多还原

【Abstract】 Direct current transmission technology has been a hot topic in the electrical engineering domain, on account of the considerably numerous advantages of it. The high voltage direct current plastic insulated cable is one of the most important equipments in DC transmission technology. Compared with paper insulated DC cables, there are many excellent characteristics of the HVDC plastic insulated cable, such as, relatively small volume, great transmission capability and maintenance-free. So it is crucial to research and develop HVDC plastic insulated cables. The non-homogenous distribution of space charge in the cable insulation may distort the distribution of electric field which will reduce the dielectric strength and accelerate the deterioration of the insulation. As a result, solving the problem of the space charge accumulation in dielectrics is the indispensable and first step to develop HVDC plastic insulated cables.The pulsed electro-acoustic method is utilized to investigate the space charge distribution in polyethylene and its composites and some conclusions can be drawn. The differences of production process among different types of polyethylene result in the differences of space charge distribution in them. Although loading with the same kind of filler and the same quantity and the base material is LDPE, LDPE produced by different corporation may also make each composite have different characteristics. The crystallization behavior of composites may also affect the space charge distribution in them. However, this affection is less effective than those of other factors, such as, the concentration of impurities. The cross-linking by-products impose great effect on space charge distribution in XLPE. The research results also show that the material of electrodes is also one of important factors which affect the space charge distribution.Loading proper quantity of nano-MgO can effectively improve the space charge distribution, the breakdown characteristics, conductivity and mechanical performances of composites. By utilizing FT-IR and DSC to investigate XLPE and MgO/XLPE nanocomposites, it can be inferred that there are some strong interaction between the molecular groups of XLPE and MgO nano-particles from analyzing the experiment results.更多还原