Development of Smart Silicone Rubber Insulating Materials for HVDC Transmission Systems

硅橡胶绝缘子显示出优异的防污染性能，因此在交流（AC）架空输电系统中已取代由瓷或钢化玻璃制成的传统绝缘子。这些绝缘子也被推荐用于高压直流（HVDC）输电线路系统，在几何形状上做一些改变，但不考虑外壳材料设计。通过增加爬电距离来修改几何形状可以确保短期内可接受的闪络性能，但老化仍然是一个非常值得关注的问题。 鉴于高压直流输电线路在电网中的应用越来越多，这一问题促使人们对开发用于高压直流输电系统的可靠的硅橡胶绝缘外壳材料产生了兴趣。 传统的硅橡胶外壳材料是基于50多年的交流绝缘子行业经验开发的。但是，这种基于经验的方法不能应用于直流绝缘子的开发，因为在直流电压下的绝缘子老化方面的经验是有限的。该研究计划提出在基于机械的框架中开发可靠、具有成本效益且智能的硅橡胶外壳材料，用于直流室外绝缘应用。根据拟议的研究计划执行以下项目。 (1)侵蚀机制：由于在外壳材料表面上引起的干带电弧而引起的硅橡胶绝缘体的腐蚀是导致在污染的使用条件下绝缘失效的关键老化机制。的DC相比，AC干带电弧的动态性质进行了研究，以开发一个电热模型的干带电弧作为热源，撞击表面，造成热烧蚀。 (2)无机填料的作用：传统上，房屋材料复合材料尽可能多地装载无机填料。作为阻燃剂的无机填料抑制了由于干带电弧导致表面分解而形成的碳质轨迹。然而，硅橡胶是耐漏电的，因此腐蚀是一个问题。本课题主要研究无机填料的防蚀效果。重点也将给予理解的作用，界面纳米尺寸的填料。因此，开发了热模型来预测使用无机填料配制用于DC户外绝缘的复合材料的侵蚀性能。 (3)材料筛选方法：为了满足绝缘子制造商和公用事业公司的需求，开发了一种用于直流户外绝缘材料耐腐蚀性鉴定的材料筛选方法，以提供与实际使用性能相关的可重复结果。

Silicone rubber insulators have shown excellent pollution performance and thus have been replacing the conventional insulators made from porcelain or toughened glass in alternating current (AC) overhead power transmission systems. These insulators are also recommended for use in high voltage direct current (HVDC) transmission line systems, with a few changes made in the geometry but with no consideration given to the housing material design. Modifying the geometry by increasing the creepage distance may ensure an acceptable flashover performance over the short term, but aging remains an issue of a great concern. In the light of the increased application of HVDC links in the electricity grid, this concern has driven an interest in developing reliable silicone rubber insulation housing materials for HVDC systems. Conventional silicone rubber housing materials have been developed based on more than 50 years of industry experience in AC insulators. But, this experience-based approach cannot be applied in the development of DC insulators as experience is limited in insulator aging under DC voltages. This research program proposes the development of reliable, cost-effective, and thus smart, silicone rubber housing materials for DC outdoor insulation applications in a mechanistic-based framework. The following projects are executed under the proposed research program. (1) Erosion Mechanisms: erosion of silicone rubber insulators as a result of dry-band arcing induced on the surface of the housing material is a critical aging mechanism leading to insulation failure in polluted service condition. The dynamic nature of the DC as compared to the AC dry-band arcing is studied in order to develop an electro-thermal model for the dry-band arcing as a heat source, impinging the surface and causing heat ablation. (2) The Role of Inorganic Fillers: Traditionally, housing material composites are loaded as much as possible with inorganic fillers. Inorganic fillers, as flame retardants, suppress the formation of carbonaceous tracks as a result of dry-band arcing causing decomposition of the surface. However, silicone rubber is tracking-resistant and thus erosion is of a concern. In this project, the erosion suppression effects of inorganic fillers are investigated. Emphasis will also be given to understand role of interface as nano-sized fillers are employed. Accordingly, a thermal model is developed to predict the erosion performance of composites formulated for DC outdoor insulation using inorganic fillers. (3) Material Screening Methods: In response to a great demand raised by insulator manufacturers and utilities, a material screening method for the qualification of erosion resistance of DC outdoor insulating materials is developed to provide reproducible outcomes that correlate with the actual performance in service.