Recently, Sutong 1000 kV UHV AC GIL integrated pipe corridor project was completed and put into operation, the project achieved a new leap in the world power grid technology, is the world's leading pioneering transmission project, and has an important milestone in the history of the development of China's power industry.

The 1000 kV UHV GIL transmission technology compreses the double 1000 kV UHV line corridor up to 450 meters and nearly 100 meters wide into a tunnel with an inner diameter of 10.5 meters. Before this, there is no mature experience and products at home and abroad for reference. In addition, Sutong GIL pipe corridor transmission, long distance, large buried depth, high voltage, there are electrical, thermal, force and surface defects, suspended particles, SF6 decomposition products, temperature and pressure changes and other complex factors, typical insulation structure, complex material characteristics, strong interface effect, multi-field coupling difficult, diverse discharge forms.

Aiming at the key core technology problems of UHV AC GIL transmission insulation and discharge in engineering, Professor Peng Zonren's team from the School of Electrical Engineering of Xi 'an Jiaotong University, in collaboration with domestic first-class switch manufacturers and scientific research institutions, mastered the electro-thermal characteristics of GIL insulation materials, interface materials and conductive materials, and obtained the multi-physical field distribution law of typical structural engineering application schemes. The methods and approaches of voltage balancing, field balancing and interface effect elimination are proposed, and the influencing factors of insulator gas-solid interface discharge are given. The causes of insulator body discharge ablation and carbonization are obtained. The configuration mode of GIL insulator and the structure type of voltage balancing shield are optimized, and the multi-physical field distribution and structure rationalization of UHV GIL insulator are realized. A series of innovative results have been achieved, providing an important basis for the independent research and development, quality improvement, test assessment and safe and reliable operation of the world's first UHV GIL transmission equipment, breaking the foreign monopoly, improving the competitiveness of similar products in China and abroad, and achieving key technology breakthroughs in UHV GIL, reducing engineering construction costs and equipment localization. It has great technical, economic and social benefits.

Sutong 1000 kV UHV GIL integrated pipe corridor project is the control project of 1000 kV UHV AC ring network across the Yangtze River in East China, and is also the "throat road" of UHV AC ring network in East China. It is connected with Huainan - Southern Anhui - Shanghai UHV project, which has been put into operation, and forms an "O-shaped" UHV AC ring network in East China that runs through the load centers in Anhui, Jiangsu, Zhejiang and Shanghai. The completion of the project has promoted the energy technology revolution, opened up the fast track of China's energy development, and strongly supported the construction of China's power grid with "three types and two networks, and world class". It has significant comprehensive benefits and long-term strategic significance for optimizing energy allocation, ensuring power supply, preventing and controlling air pollution, driving economic growth, and leading technological innovation.