China’s Power: giant offshore substation launched for wind energy

In the South China Sea, off the coast of Guangdong Province, China is demonstrating its ambitions in renewable energy by completing the installation of the world’s largest conversion substation for offshore wind farms. This engineering masterpiece, unofficially nicknamed the “Heart of Offshore Wind,” is set to become a key link in transmitting clean energy from offshore installations to the mainland grid. Its annual output is expected to reach an impressive 6 billion kilowatt-hours, significantly reducing dependence on fossil fuels and cutting harmful emissions into the atmosphere.

The power of the ocean at the service of energy: project details

This monumental structure, located about 100 kilometers from the coast, is the world’s first flexible offshore DC conversion substation operating at 500 kilovolts and with a peak capacity of 2000 megawatts. Its construction and installation are a testament to the rapid development of China’s industry and its drive to become a leader in green technologies. The final stage of the project includes laying the subsea cable, as well as comprehensive onshore and offshore testing, before the substation is put into commercial operation.

Once the project is fully operational, annual carbon dioxide emissions are projected to be reduced by nearly 5 million metric tons. This is a significant step toward achieving environmental goals and combating climate change. The installation of this titanic structure took about 7 hours, which is impressive given the scale and complexity of the operation.

According to official data from the State-owned Assets Supervision and Administration Commission (SASAC), the conversion substation consists of two giant sections. The first is a multi-story steel topside, seven stories high. The second is a jacket-type support structure firmly fixed to the seabed.

The upper platform, the “heart” of the substation, has impressive dimensions: 85.5 meters in length, 82.5 meters in width, and 44 meters in height. It weighs about 25,000 metric tons. This topside rests on a jacket support structure measuring 82 meters long, 57 meters wide, and 69 meters high. The base weighs 17,000 metric tons.

Engineering challenges and innovative solutions

The distinctive feature of this project is not only its scale, but also the complexity of the marine environment in which it will operate. The structure must withstand extreme conditions: strong winds, powerful waves, ocean currents, aggressive saltwater corrosion, dense sea fog, and frequent typhoons typical of this region. To ensure stability and safety, the structure is securely anchored to the seabed with 8 giant foundation piles.

The massive weight of the conversion station — exceeding the cargo capacity of any Chinese vessel — had to be managed by engineers using innovative methods. Instead of traditional lifting, the semi-submersible vessel “Xiang Tai Kou” was used. This ship, specially designed or adapted for such tasks, made it possible to lift the massive steel platform and then carefully and precisely position it onto the support frame.

The installation process was a real test of precision. It depended heavily on tidal movements and the vessel’s dynamic positioning system. This advanced technology made it possible to guide the platform into place with exceptional accuracy. During installation, the gaps between the upper structure and the foundation were minimal — just 150 mm on each side.

To provide additional protection and absorb possible impact loads, special rubber protective covers and innovative connecting devices were installed on the foundation supports. These elements ensured safe alignment of the platform before its final fastening.

Preparing for equipment installation required careful planning. Project teams closely monitored weather forecasts from numerous meteorological services to choose the optimal period with the most favorable wind and sea conditions.

The “Heart of Offshore Wind” substation is already demonstrating top performance in marine durability, power transmission capacity from offshore wind projects, and unique flexible direct-current transmission systems. This is another step for China toward dominating the global renewable energy industry, demonstrating their commitment to technological advancement and sustainable development.