Dual Power Sources to Strengthen Island Grid as Wenzhou Launches 110kV Submarine Cable Installation

On May 7, the Wenzhou Dongtou Changqing-Shenshui 110kV transmission line project officially started submarine cable installation in the waters between Zhuangyuan'ao Island and the southwest end of Damen Island. Two submarine cables with a combined length of 20.6 kilometers are being laid, marking the key offshore construction phase of Wenzhou's first 110kV submarine cable project.

Each of the dual-circuit submarine cables measures 10.3 kilometers, adopting 3×630 mm² three-core steel-armored XLPE-insulated composite fiber-optic submarine cables, with a designed transmission capacity of 122 MVA. The project also includes overhead line construction and expansion of related facilities at Changqing 220kV Substation. Upon completion, it will form a robust power grid featuring dual-source backup capability and north-south grid interconnection.

Construction uses China's first domestically built 5,000-ton cable-laying vessel "Qi Fan 9". Technologies such as trenching, precision cable burial, and multibeam surveying are applied, with cables buried 3.5 meters deep in navigation channels for safety and accuracy. Green construction methods—including horizontal directional drilling and simultaneous dual-circuit installation—protect the marine ecology. Full-process supervision over fund use and construction management has been implemented to ensure clean and efficient project delivery.

Cable laying will take 10 days, and the project is scheduled for operation by the end of May. It will end Wenzhou Dongtou's reliance on a single power supply route, address structural weaknesses in the island power grid, improve power supply reliability in extreme weather, and strongly support local livelihoods, tourism and the marine economy.

(By Zhang Hong, Zeng Hao)