China has shipped the world’s largest offshore converter station for installation at sea, where it will connect two massive offshore windfarms to the national power grid.

The platform, a two-gigawatt (GW) energy hub named Haifeng Heart, was built by heavy-duty equipment manufacturer Shanghai Zhenhua Heavy Industries Co., Ltd. (ZPMC). It departed from the port city of Nantong in China’s Jiangsu Province on Wednesday, May 27.

The converter station is now headed to offshore waters near the city of Yangjiang, Guangdong, for the next phase of installation. Once commissioned, it is expected to deliver approximately six billion kilowatt-hours (kWh) of renewable electricity per year.

The system will supply clean electricity to homes and businesses while advancing China’s decarbonization efforts. According to the firm, the facility will support the Three Gorges Yangjiang Qingzhou V and Qingzhou VII offshore wind farms.

China’s offshore milestone

The eight-story steel structure is about 281 feet (85.5 meters) long, 271 feet (82.5 meters) wide, and around 144 feet (44 meters) high. It also weighs an astonishing 25,000 tonnes (27,557 US tons).

It is among the largest offshore energy structures ever built. ZPMC revealed that it was constructed using a modular fabrication approach, with onshore assembly, equipment integration, and installation progressing in parallel. This placed high demands on supply chain coordination and production management.

Yan Bing, ZPMC senior specialist, stated that the company adopted an integrated construction model featuring “onshore assembly, transport as a single unit, and float-over installation.” This improved the efficiency and execution quality, while providing a model for future projects of this type.

“Haifeng Heart will serve the centralized subsea cable transmission project for the Three Gorges Yangjiang Qingzhou V and Qingzhou VII offshore wind farms,” the company said in a press statement.

A record-breaking wind hub

ZPMC pointed out that the project set six major industry records. It has a single-unit transmission capacity of 2,000 megawatts (MW). This makes it the largest offshore converter station in the world.

Moreover, it will support the Three Gorges Yangjiang Qingzhou V and Qingzhou VII offshore wind farms, which together have a total installed capacity of two GW.

At the same time, it also boasts the world’s highest-voltage offshore wind flexible direct-current (DC) transmission system. The system runs at ±500 kilovolts (kV). It extends the application of flexible DC technology in offshore wind power.

It is the first offshore wind project to combine alternating current (AC) and DC transmission technologies within the same system. Additionally, the project is the first centralized offshore wind flexible DC transmission system of its kind.

It additionally marks the first use of ±525 kV DC subsea cables for long-distance transmission of renewable energy generated offshore. The firm emphasized the importance of offshore converter stations. Wind turbines produce alternating current (AC) electricity. Transmitting power over long subsea distances using AC can result in significant energy losses.

“By converting offshore AC into DC, they reduce transmission losses over long-distance subsea cables, unlocking access to high-quality wind resources located more than 100 kilometers [62 miles] from shore and supporting expansion into deeper and more remote waters,” ZPMC concluded.

Source: Interesting Engineering