HKZ Beta Topside In Place, HKZ Alpha Ready for Use

The topside of the Hollandse Kust Zuid (HKZ) Beta offshore substation has been installed on its jacket foundation in the Dutch North Sea, TenneT said.

The HKZ Beta topside was loaded from the transport vessel onto Allseas’ platform installation vessel Pioneering Spirit in the Alexiahaven.

The Pioneering Spirit then sailed to the installation site and, after completion of preparatory work, accurately positioned the Beta topside on the jacket this week, TenneT said.

The project to connect the 1.5 GW HKZ wind farm to the Dutch grid reached another milestone earlier this month when the HKZ Alpha substation received the ‘Grid Readiness’ certification from DNV GL.

The certificate confirms that this offshore grid connection fully complies with the conditions set out in the so-called Offshore Wind Energy Development Framework and that the wind farm’s developer, Vattenfall, can now connect the wind turbines to the high voltage grid.

“With the energization of the Hollandse Kust (zuid) Alpha connection, the offshore grid that TenneT is building in the North Sea is starting to take shape. Hollandse Kust (zuid) Alpha is the first connection of an offshore wind farm to the Maasvlakte and has a capacity of 700 MW. The energization of Hollandse Kust (zuid) Beta later this year will add another 700 MW from wind farms Hollandse Kust (zuid) III and IV,” Marco Kuijpers, Director of Large Projects Offshore at TenneT, said.

The 700 MW, 3,950-tonne HVAC offshore transformer station has been delivered to TenneT by Petrofac, who also delivered the Hollandse Kust Zuid Alpha substation in cooperation with Drydocks World Dubai.

The Beta topside left the fabrication yard in Dubai in February and sailed on a Boskalis transport vessel in little over one month to the Alexiahaven on the Maasvlakte, where it arrived last week.

”The safe installation of the Beta topside is a significant milestone in the delivery of this important energy transition project. Everyone involved should be proud of this achievement,” Sami Iskander, Petrofac Group Chief Executive, said.

Located 20 kilometers off the Dutch province of Zuid-Holland, the HKZ wind farm zone occupies an area of 235.8 square kilometres, where Vattenfall is building four wind farms as part of the project.

Once fully operational in 2023, the 1.5 GW Hollandse Kust Zuid will become the largest operating offshore wind farm in the world. Comprising 140 Siemens Gamesa 11 MW wind turbines, the subsidy-free wind farm will generate enough electricity to meet the annual needs of more than two million households.

The electricity generated by the wind turbines will be collected at an offshore transformer station where the voltage will be converted from 66 kV into 220 kV.

The electricity will then be transported via export cables in the seabed to the electrical substation at the Maasvlakte. At this substation, the voltage will be converted into 380 kV before being transported to the high voltage grid via high voltage station Randstad 380 kV Zuidring.

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