基于非线性复合材料均压结构的高压直流套管基础研究

The HVDC bushing is the key equipment for high voltage DC power transmission projects. There has been a rapid growth of the market demand for HVDC bushings in China, but the foreign suppliers always monopolized the market. The main technical bottleneck of HVDC bushings is the uneven distribution of electric field. In addition, the special conditions such as DC polarity reversal, AC and DC superposition, and the coupling of temperature field and electric field, bring much more difficulties to the design and manufacture of HVDC bushings. The fundamental research on HVDC bushing with multi-layer insulation structure composed of nonlinear composites is proposed by this project. The nonlinear composites will be used to improve the distribution of electric field inner the insulation parts of HVDC bushings, and a novel solution based on multi-layer insulation structure which is composed of nonlinear composites will be designed for the HVDC bushings. The multi-layer insulation structure composed of nonlinear composites will be prepared by bending the organic polymer solid insulating matrix and non-linear inorganic fillers. As a result, the HVDC bushing will have better performance of insulation breakdown strength, electric field distribution and heat dissipation, which leads to less potential faults and higher reliability.

高压直流套管是直流工程的关键设备之一，市场需求巨大但长期由国外供货商垄断。制约高压直流套管的主要技术瓶颈是电场分布的不均匀问题，此外直流极性反转、交直流叠加等特殊工况，以及内部绝缘介质存在复杂的温度场、电场耦合问题，使得高压直流套管在设计制造上更为困难。本项目拟开展基于非线性复合材料均压结构的高压直流套管基础研究，采用非线性复合材料调控介质内部空间电场分布的创新技术路线，提出研制全新均压结构高压直流套管的设计方法和实现方案；利用有机聚合物固体绝缘基体与非线性无机填料共混制备工艺，研制适用于高压直流套管的非线性复合材料多层组装的新型均压结构，保证套管内部绝缘耐受强度高、各向电场分布均匀、散热性能良好，从根本上避免套管内部介质容易出现的异常放电、介质损耗增大等问题，从而显著提升高压直流套管类设备运行的安全可靠性。

高压直流套管作为直流输电工程中的现场关键设备，市场需求巨大。由于其生产制备复杂、产品质量控制困难，至今仍被国外供应商垄断。即使是国外高端产品，在实际工程中存在不少问题。制约直流套管制作的主要技术瓶颈是由于其内部极不均匀的电场分布。针对这一难题，本项目提出了采用非线性符合材料调控介质内部电场分布的创新技术路线。课题组围绕项目研究内容，开展了如下工作：从局部均压与全局均压、等效电极、局部放电和材料选择四个方面开展研究，建立了非线性复合材料应用于高压直流套管的分析模型；提出了综合考虑导杆选择、主绝缘设计、接地屏设计、电极延伸层设计及参数选择、外绝缘设计五方面因素的自适应套管设计原则，提出了自适应套管芯体设计的重要调控指标及其主要影响因素，并据此对±800 kV电压等级的自适应直流穿墙套管进行优化设计。提出了适用于高压直流套管的非线性复合材料的选型和电、热和机械性能的联合调控方法。揭示了直流套管均压结构中不同介质层结合界面的界面特性和整体响应特性。与南京电气合作，完成了±800 kV非线性材料套管的缩尺样机的研制，并对其先后开展了等效工况下的交流、直流、雷电冲击等试验，获得了该样机的服役特性，并验证了材料特性及设计方法。项目成果具有较好应用前景，有望为国内外高压套管产业带来开创性的技术路线升级。