Recently, the first UHV AC project in southwest China, the Sichuan-Chongqing 1000 kV UHV AC project of the State Grid Co. The project will build four new UHV substations in Ganzi, Tianfu South, Chengdu East and Tongliang, Chongqing, with a transformer capacity of 24 million kVA and 658 km of new double-return UHV lines, with a total investment of 28.8 billion RMB, and is scheduled to be put into operation before the summer peak in 2025.
Compared with similar projects completed so far, Sichuan-Chongqing UHV AC project is the world's highest altitude UHV AC transmission project, the highest altitude of UHV transmission line will jump from the existing 2300 meters to more than 4700 meters; the highest altitude of China's 1000 kV substation will jump from 1300 meters to 3500 meters, and the equipment size will increase by more than 30%. The construction of the project faces the triple challenges of high altitude, heavy ice cover and high seismic intensity at the same time. To this end, the technical research team of State Grid Corporation has overcome the key technologies of high altitude air gap, external insulation, electromagnetic environment and equipment development, and successfully developed a full set of high altitude EHV equipment and special construction tools, laying the technical foundation for the first time in the world to complete the construction of EHV at high altitude and heavy ice cover.
Sichuan-Chongqing UHV AC project is the starting project to connect Sichuan and Chongqing power and load centers and build the backbone of southwest UHV AC network. After the completion of the project, the voltage level of the main network of China's southwest power grid will be raised from 500 kV to 1000 kV, which will deliver clean electricity of over 35 billion degrees per year, which can strongly meet the needs of diversified power supply development and transmission, effectively undertake the electricity from northwest China and Tibet, and significantly improve the overall power security capacity of the twin-city economic circle in Chengdu and Chongqing. It is important to build a clean, low-carbon, safe and efficient energy system and guarantee regional energy security.