World's highest-voltage offshore VSC converter station sets sail

(ECNS) -- The offshore converter station of the Yangjiang Sanshandao offshore wind power VSC-HVDC (voltage source converter-based high-voltage direct current, also known as flexible DC transmission) project has set sail, marking the completion of its onshore construction phase and the start of offshore transport and installation, according to a statement on Wednesday from Guangdong Power Grid Co. of China Southern Power Grid.

The station currently ranks first in the world in both voltage class and transmission capacity, the company said.

With a voltage class of ±500 kV and a transmission capacity of 2,000 MW, the station integrates core converter equipment, electrical systems and auxiliary facilities.

The Sanshandao project is China's first integrated offshore-onshore VSC-HVDC transmission project. The offshore converter station, its core hub, set sail from Nantong, Jiangsu Province, on Tuesday night and is expected to arrive after a voyage of about 1,000 nautical miles that will take five to seven days.

The station is a seven-story steel platform measuring 85.5 meters long, 82.5 meters wide and 43 meters high, roughly the height of a 15-story building, with each floor covering nearly the area of a standard football pitch. It weighs about 25,000 tonnes.

Wan Pingping, an engineer with Guangdong Power Grid Co., said the project uses an integrated offshore-onshore DC transmission model to meet the demands of large-scale offshore wind power development, effectively addressing the technical challenges of transmitting such power over long distances and at large scale.

Designed for the harsh offshore environment, the station uses anti-corrosion technology and an integrated seismic- and typhoon-resistant framework capable of withstanding Category 17 typhoons and magnitude-8 earthquakes.

The station will transmit 2,000 MW of offshore wind power from the waters off Yangjiang to the load center of the Guangdong-Hong Kong-Macao Greater Bay Area via a 115-km submarine DC cable and a 180-km onshore DC overhead line.

"The Sanshandao project extends the reach of China Southern Power Grid's main grid into deep-sea areas for the first time," said Luo Tao, general manager of the infrastructure department at Guangdong Power Grid Co. "It enables the unified transmission of multi-terminal far-offshore wind power to load centers, improving corridor efficiency, saving land resources and achieving intensive use of transmission corridors."

(By Tang Yuxian)