特高压气体绝缘金属封闭输电线路绝缘设计

Research on Insulation Design of UHV Gas-Insulated Metal-Enclosed Transmission Line

气体绝缘金属封闭输电线路(gas-insulated metal-enclosed transmission line,GIL)是架空输电方式在地理或环境条件受限情况下的重要补充,在特高压工程中具有较好的应用前景。研究特高压GIL的绝缘设计关键技术,包括典型绝缘结构型式、间隙设计与优化、绝缘子设计与优化、金属微粒抑制和混合气体方案探讨。提出了GIL间隙设计的原则和电场控制值,优化设计了电连接的两段圆弧连接式倒角结构,较好地满足了电场控制值要求。提出了GIL绝缘子设计的原则和电场控制值,优化设计了一种屏蔽电极结构和绝缘子形状综合优化的盆式绝缘子结构,全面满足了电场控制值要求。分析了GIL中金属微粒的运动特性,指出需在绝缘子附近装设微粒陷阱,并开展金属微粒老练试验。分析了SF6/N2混合气体GIL的绝缘特性、设计原则及电场控制值,指出最优混合比为20%。所得研究结果有助于提升我国特高压GIL设计技术水平,促进设备研制工作。

Gas-insulated metal-enclosed transmission line（GIL） is important supplement for overhead transmission line under restricted geographic and environmental conditions. It has wide application prospect in ultra high voltage（UHV） engineering. Key technologies of insulation design for UHV GIL were investigated, including typical insulation structure, gap design and optimization, insulator design and optimization, inhibition of metal particles and mixed gas scheme. Design principle and electric field criterion for gaps in GIL was discussed. Connection structure of two adjacent circular chamfering was optimally designed for electrical connection, well meeting electric criterion. Design principle and electric field criterion for GIL insulators was put forward. Basin-type insulator structure with comprehensively optimized shield electrode and insulator shape was designed, completely meeting electric criterion. Movement characteristics of metal particles in GIL were analyzed. It was concluded that it was necessary to install particle traps near insulators.Ripening tests for metal particles were performed. Finally, insulation property, design principle and electric field criterion of mixed gas SF6/N2 in GIL were discussed. Results showed that optimal mixing rate of SF6 is 20%.