About the grid connection
From the platforms there will be a total of four alternating current cables that run to the high-voltage substation De Maasvlakte on the mainland.
Onshore they will be connected to the the Randstad 380 kV South Ring.. Hollandse Kust (zuid) Alpha will go into service in 2021 and Hollandse Kust (zuid) Beta in 2022.
TenneT has officially been appointed as offshore grid operator in the Netherlands, and will develop -as contribution to the Energy Agreement- at least 3,500 MW of offshore-connections until 2023; all with a standardised concept of 700 MW per connection.
The project to connect the 1.5 GW HKZ wind farm to the Dutch grid reached another milestone earlier 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
The 700 MW, 3,950-tonne HV/AC offshore transformer station has been delivered to TenneT by Petrofac, who also delivered the Hollandse Kust Zuid Beta substation in cooperation with Drydocks World Dubai.
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.
