Van Oord has started installing the export cables which will connect the 1.5 GW Hollandse Kust (zuid) offshore wind farm to the Dutch grid, TenneT said.
For the first ten kilometres of the cable route at sea, the four export cables will have to be buried more than 5,5 metres into the seabed in order to cross the busy shipping route – Rotterdam Maasmond.
The installation of the cables started on September 22nd by pulling the cable ashore.
Van Oord’s Deep Dig-It trencher crossed the Rotterdam Maasmond and is on its way to the recently installed offshore Alpha jacket in the Hollandse Kust (zuid) wind farm area.
The Van Oord/Hellenic Cable consortium is providing and installing the four subsea 220 kV AC cables that will connect two offshore platforms to the onshore electricity grid on behalf of TenneT.
The first two cables to the HKZ Alpha platform will be installed this year. The other two cables, which will connect the HKZ Beta platform, will follow in 2021.
The last few days the preparatory work has been completed. The cable was pulled ashore via a direct drill to the new transformer substation that is being built on the Maasvlakte.
From this point, the cable with a total length of 42 kilometres, will be laid by the contractor combination Van Oord – Hellenic Cables. For this purpose, Van Oord has specially developed the Deep Dig-It, a large remote-controlled trencher.
The Deep Dig-It is a Tracked Remotely Operated Vehicle (TROV) that drives unmanned over the seabed and creates a deep trench for the cables by liquefying the seabed. At the same time, the trencher inserts the cables into the trench and seals them again into the seabed. The Deep Dig-It is controlled at Van Oord’s offshore installation vessel MPI Adventure, which is also equipped with a crane to launch and take out the Deep Dig-It.
Hollandse Kust (zuid)
The Hollandse Kust (zuid) offshore wind farm is located 22 kilometres off the coast of the Dutch province of Zuid-Holland. The project is being developed by Vattenfall.
The sea cables connect the two offshore platforms with the Maasvlakte high-voltage substation and the Randstad 380 kV South ring. The wind energy is then fed into the national high-voltage grid to the electricity consumers in the Netherlands.
The 1,400 MW HKZ grid connection will be completed in 2022 and will eventually provide electricity for 1.6 million households.