Borssele Beta is the second high-voltage grid connection for offshore wind farms in Dutch territorial waters of the Dutch-German transmission system operator (TSO) TenneT. Like Borssele Alpha, the first Dutch offshore connection, it transmits green electricity generated in the Borssele wind farm area ashore, in this case from the Borssele III, IV and V wind farms. The operators of these three farms can hook up their wind turbines to the high-voltage grid one month earlier than scheduled, as TenneT has just received the “Grid Readiness” certification from the internationally accredited registrar and classification society DNV GL. This means that Borssele Beta fully complies with the criteria of the “Ontwikkelkader windenergie op zee”, the Offshore Wind Energy Development Framework of the Dutch Government.
The Borssele III, IV and V wind farms will have a total capacity of 700MW. The electricity generated here is collected by the offshore transformer platform, which converts the voltage from 66kV to 220kV for transmission via submarine cables to the onshore substation in Borssele. For feeding into the high-voltage grid, the voltage is then converted to 380kV. Marco Kuijpers, Director Offshore Projects at TenneT, comments on the rapid realisation: “We are proud of the fact that the second part of the Borssele high voltage connection is already complete and was realised within budget. Despite all the Covid-19 challenges, we were successful in continuing with the works; a huge achievement from all the contract parties involved.”
By the end of 2023, TenneT will have installed 3.5GW of offshore grid connections in the Netherlands, of which the first 1.4GW have already been achieved with Borssele Alpha and Beta. The next projects are Hollandse Kust (zuid) Alpha and Beta, followed by Hollandse Kust (noord). For these wind farms, TenneT will deploy five identical 700MW transformer platforms and identical 220kV cable connections. This standardisation allows TenneT to realise these projects faster, more efficiently, and more economically. The governmental Dutch follow-up roadmap for offshore development provides for an additional 6.1GW of offshore wind farms from 2024 to the end of 2030, located in the wind energy areas Hollandse Kust (west), Ten Noorden van de Waddeneilanden and IJmuiden Ver. Only for the first two, TenneT will again use standardised 700MW platforms. The efficient connection of IJmuiden Ver, located further out in the North Sea, partly requires other technologies based on DC instead of AC. IJmuiden Ver will have two offshore transformer platforms with a capacity of 2GW each, which is unique in the offshore wind industry.