Construction start of DolWin 6 converter station

24.10.2019

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)

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TenneT on track for the energy transition

31.07.2019

Highly satisfactory business results and maintenance of the high level of 99.99% security of supply, are hallmarks of the half year report of the Dutch-German TSCNET shareholder Tennet. The latter is a growing challenge for the transmission system operator (TSO) because of the increased feed-in of volatile renewable energy. But above all, the report illustrates the commitment of the TSO to the European energy transition.

To take further steps in shaping the energy system of the future, TenneT has launched a series of strategic initiatives and partnerships to join forces across sectors. TenneT is participating in a German power-to-gas pilot project and is working together with regional grid operators and market partners on smart solutions to optimise the use of existing electricity infrastructure. The TSO is also involved in blockchain pilots to create flexibility for balancing the power system from decentralised sources.

TenneT has further strengthened its position as a leading offshore TSO. In Germany, TenneT has awarded DolWin 5, the 14th offshore grid connection. TenneT will increase its current offshore transmission capacity from 6,232MW in the German North Sea to almost 9GW by 2024. In the Netherlands, too, the development of the offshore grid with the Borssele Alpha and Beta projects is on schedule. TenneT intends to provide a total of 10.6GW of connection capacity for Dutch offshore wind farms by 2030. The TSO is also carrying out several onshore projects to ensure the transport of the growing amount of green electricity and thus security of supply in its control areas. Important interconnecting projects are the NordLink cable connection, which is currently being built to directly link the German and Norwegian markets for the first time. The COBRAcable between the Netherlands and Denmark has “landed” at the Dutch shore and will go into operation this year.

These developments are complemented by solid and impressive figures: Underlying operating result (EBIT) rose from €362m (first half of 2018) to €407m in the first half of 2019. €1,094m (first half of 2018: €904m) were invested in the Dutch and German high-voltage grids (of which €612m in Germany) and a total of €1.75bn green bonds were successfully issued. Manon van Beek, CEO of TenneT, comments on the report: “We have embarked on an irreversible transition to a sustainable society and a new energy system. This requires investments, not only in new electricity connections, but also in innovations and digitalisation. We have to move to holistic energy system thinking and also work on solutions to make better use of the existing high-voltage grids. We are convinced that this is the way forward to limit social costs and at the same time maintain a very high security of supply.”

TenneT presents its half year report 2019 (picture: TenneT)

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66kV technology reduces offshore connection costs

08.05.2019

In future offshore projects, TSCNET shareholder TenneT will continue to reduce grid connection costs through standardisation and innovative technology. For the DolWin5 offshore grid connection in the so-called DolWin cluster in the south-western part of the German Bight, the Dutch-German transmission system operator (TSO) has contracted a consortium consisting of Aibel and Keppel FELS with ABB as subcontractor with the design, engineering, procurement, construction, installation and commissioning of a 900MW offshore HVDC converter platform and an onshore converter station.

The outstanding feature of the DolWin5 project is the innovative connection concept. The innovative 66kV technology from TenneT, which will be deployed, represents a new generation of low-cost offshore grid connections. The wind turbines will be directly connected to the offshore platform without the need for separate substations for the wind turbines. This direct connection not only omits any further substations but also the 155kV three-phase power cables for linking the wind farm to the offshore platform. Instead, 66kV three-phase cables will be used.

“With DolWin5 we open a new chapter in offshore grid connection technology: For the first time, the wind turbines are directly connected to our offshore platform,” comments TenneT COO Tim Meyerjürgens and adds: “This innovative technology results in an enormous cost reduction. The new direct connection will save around €200m in macroeconomic terms.”

TenneT opts for the innovative 66kV three-phase technology for future offshore connections (Picture: TenneT)

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