Construction start of DolWin 6 converter station


The so-called DolWin wind farm cluster in the southwestern part of the German Bight is an important component of Germany’s future regenerative energy supply. TSCNET shareholder TenneT, the Dutch-German transmission system operator (TSO), is responsible for transferring the DolWin energy ashore. The DolWin1 and 2 onshore connections are in operation since 2015 and 2016 respectively, and DolWin 3 is ready for feed-in since September 2018. The other ongoing projects, DolWin 5 and 6, are also making good progress.

DolWin6 is a 900MW DC connection with a length of 90km. The associated offshore platform to convert the three-phase current generated by the wind farms into DC is DolWin kappa. Half of the 90km distance is covered by submarine cables and the other half by underground cables to transport the electricity from the landing site in Hilgenriedersiel to the TenneT facilities in Emden in the Lower Saxony region of East Frisia.

On the grounds of the Emden/Ost substation, the TSO is building a converter station and a transformer station to convert the DC back into three-phase current and feed it into the onshore grid. The first construction phase of the DolWin6 onshore converter station has now begun with the foundation work. In the next 6 months, 1000 piles with a length of up to 24 meters will be drilled into the ground to create a stable foundation for the station.

TenneT begins construction of the DolWin6 onshore converter station (pictures: TenneT)

> See TenneT Tweet, in German (html)

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Early DolWin2 reconnection


Due to repeated cable component failures, TSC member TenneT, the Dutch-German transmission system operator (TSO), had to disconnect the DolWin2 offshore grid connection from the onshore transmission grid on 7 November 2016. The DolWin2 DC power line links the offshore wind farms Nordsee One, Gode Wind I and Gode Wind II in the German Bight to the transmission system with a capacity of 916MW and a total length of 135 km. Already on 7 January 2017, which is more than eleven weeks earlier than expected, TenneT was able to reconnect DolWin2.

Apart from the tremendous efforts of all the people directly involved in the repair works, there are three main factors for this significant reduction in switch-off time. Firstly, the close and constructive cooperation between TenneT and the multinational technology corporation ABB, the general contractor for DolWin2. Secondly, the inclusion and the commitment of all the affected companies, landowners and authorities. And finally, the unusual dry weather in the last two months of 2016 was also a crucial element and accelerated the repairs perceptibly.

> See TenneT press release (html)

Picture: TenneT


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