TenneT has energised the Hollandse Kust Zuid (HKZ) Alpha grid system, a 700MW high voltage connection for offshore wind farms HKZ 1 and 2.
TenneT received the Grid Readiness certification from DNV GL for HKZ Alpha on 22 March, which means the offshore grid connection fully complies with the conditions set out in the so-called Offshore Wind Energy Development Framework.
This step allows for the turbines to be connected to the grid.
Marco Kuijpers, director of TenneT’s large offshore projects, said: “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 700MW.”
The grid operator has meanwhile completed the installation of the HKZ Beta topside.
Kuijpers added: “The energisation of Hollandse Kust (zuid) Beta later this year will add another 700MW from wind farms Hollandse Kust (zuid) III and IV.”
Contractor Petrofac fabricated the two HV alternating current (HVAC) transformer stations – also called topsides – Alpha and Beta at the Drydocks World fabrication yard in Dubai.
The Alpha topside was installed on the jacket in the North Sea, about 20 km off the coast of The Hague, on 26 December 2021.
Sister topside Beta 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.
Offshore company Allseas carried out the installation
In the Alexiahaven, the Beta topside was loaded from the transport vessel onto the platform installation vessel Pioneering Spirit of offshore company Allseas, which then sailed to the installation location at sea.
After completion of preparatory work, Pioneering Spirit accurately positioned the Beta topside on the jacket this week.
Petrofac group CEO Sami Iskander said: “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.”
Kuijpers added: “I am very pleased that the project was installed safely and I compliment Petrofac and Allseas with this.
“Wind energy plays a crucial role in the energy transition, also in industry, and I am proud that TenneT, together with our partners, can contribute to a sustainable future in this way.”
By the end of 2023 TenneT will have constructed 3500MW offshore grid connections for offshore wind farms in the Dutch North Sea.


