The first AC unit for Qinghai-Henan UHV DC project (Qinghai side) arrived at the site

The first 700 MW / 750 kV site-assembled transformer Produced by BTW(Qing Huangdao) has been successfully transported from the Converter Assembling Workshop of State Grid Qinghai Electric Power Xining Maintenance Base to the project sending port of± 800 kV Hainan converter station after 4 days transportation on January 5. This is for Qinghai-Henan±800 KV UHV DC project (Qinghai side) which belongs to China's first clean energy EHV outgoing channel.

This 750 kV AC transformer will be used in Qinghai-Henan±800 KV converter station, it is the first transformer which successfully assembled in the first UHV converter on-site assembly plant in China, and was assembled completely in Xining converter assembly plant at the end of 2019 and passed all the factory tests.

The Qinghai-Henan±800 KV UHV DC project is a major innovation in the development and utilization of UHV transmission technology to promote large-scale development and utilization of new energy in China. The project starts at Qingnan Converter Station in Hainan Tibetan Autonomous Prefecture, Qinghai Province, passes through 4 provinces -Qinghai, Gansu, Shaanxi, and Henan, and ends at Zhumadian Converter Station in Henan Province. The total length of the line is 1,562.872 kilometers, and the total investment is about 22.6 billion CNY, the project was started in December 2018 and is scheduled to be completed and put into operation in mid-2020.

BTW subcontracted total 28 units converter transformers and 6 units 750 kV AC transformers at both the high and low ends of Hainan Station from Qinghai-Henan ± 800 kV UHV DC transmission project from the State Grid Corporation of China. Among which, the 7units high-end converter transformers and 2 units 750 kV AC transformers required for the Qinghai side for the project will be assembled and tested at the Xining Maintenance Base.

Generally, transformers need to be assembled in the factory of manufacturer before the transportation to the substation. Domestic converter transformer manufacturers are mainly concentrated in the central and eastern regions. The size and weight of UHV converter transformers are too large to meet the requirements of railway transportation under normal circumstances, whereas, there are multiple transportation obstacles such as bridge loads and toll gates when transporting the converter transformers by road, hence the project adopts the technical scheme of assembling on site in Qinghai.

The successful assembly on site and successful transportation to the site of this 750 kV AC transformer, accumulated valuable experience for the smooth assembly and transportation of the ± 800 kV high-end converter transformers, and laid a solid foundation for the smooth progress of the project in the future.