BorWin5 is to become the 15th offshore grid connection system implemented by the Dutch-German transmission system operator (TSO) TenneT in the German North Sea, the twelfth DC connection, and the fourth offshore grid connection off the coast of the island of Borkum using HVDC transmission technology. With a total length of 230 kilometres, BorWin5 will also be the longest offshore connection of the TSCNET shareholder. The realisation of BorWin5, expected to be commissioned in 2025, is progressing well, as TenneT has now placed orders for the construction of the onshore and offshore converter stations as well as for the production and installation of the DC underground and submarine cables. The contract for the converter stations has been awarded to a consortium of Siemens and Dragados Offshore and for the cables to NKT HV Cables.
The key technical data of BorWin5 reflect TenneT’s extensive experience and expertise in the offshore sector on the one hand, and the TSO’s commitment to constantly improving established technology on the other. For example, BorWin5 is the second project, after DolWin5, in which the wind turbines are connected directly to the corresponding offshore platform via 66-kv three-phase power cables. This dispenses with, among other things, the transformer stations otherwise required in wind farms. With this direct connection, BorWin5 represents the new generation of cost-efficient offshore connections. Moreover, with BorWin5’s smart platform concept, the TSO is advancing standardisation further by installing only such technology on offshore platforms as is absolutely necessary on the offshore side.
Tim Meyerjürgens, COO of TenneT, emphasises the company’s continuous cost reduction in the construction of offshore grid connection systems – a highly significant aspect for the success of the energy transition – and the specific cost efficiency of BorWin5: “Compared to the predecessor project DolWin5, we were again able to achieve a significant cost reduction for the converter stations. One reason is that for BorWin5 the smart platform concept is being used for the first time. This not only keeps the costs for the platform construction manageable, but also allows us to extend the intervals for maintenance and servicing to once a year.”
TenneT awarded contracts for the on- and offshore converter stations as well as the underground and submarine cables for BorWin5 (picture shows the preparatory horizontal drilling for BorWin5 on Norderney in 2019)
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