DolWin 1 & 2: Bringing Offshore Wind Power to the Mainland Grid

DolWin 1 & 2: Bringing Offshore Wind Power to the Mainland Grid


DolWin 1 & 2: Offshore Wind Farm Specifications

DolWin 1 & 2: Bringing Offshore Wind Power to the Mainland Grid 

DolWin 1 and 2 are high-voltage direct current (HVDC) converter platforms that play a crucial role in transmitting clean energy generated by offshore wind farms to the mainland grid in Germany. These innovative projects demonstrate the technological advancements in harnessing wind power and integrating it into the national grid.

Table: Key Facts of DolWin 1 & 2 Offshore Wind Farm

FeatureDolWin 1DolWin 2
Capacity (MW)450916
Wind farms connectedBorkum Riffgrund 1 & Trianel Windpark Borkum, Merkur OffshoreNot specified
Converter platform typeFixedFloating (DolWin beta)
Transmission distance (submarine & underground cable)90 km (submarine) + 45 km (underground)135 km (total)
Operational since20152019
Owned byTenneTTenneT

DolWin 1:

DolWin 1, commissioned in 2015, was a pioneering project in connecting offshore wind farms to the mainland grid. It utilizes a fixed converter platform in the North Sea that receives electricity from nearby wind farms via alternating current (AC) cables. The platform then converts the AC power to DC for efficient transmission through subsea and underground cables over a distance of 135 kilometers to the onshore converter station. There, the DC power is converted back to AC and fed into the German extra-high voltage grid.

DolWin 2:

DolWin 2, operational since 2019, incorporates several advancements over its predecessor. Notably, it features DolWin beta, the world's most powerful floating converter platform at the time of its construction. This innovative design eliminates the need for pile driving, simplifying installation and minimizing environmental impact. DolWin 2 boasts a higher transmission capacity of 916 MW, enough to power over one million households with clean energy annually.

Significance of DolWin Projects:

The DolWin projects are instrumental in Germany's transition towards a sustainable energy future. By efficiently integrating offshore wind power into the national grid, they play a vital role in:

  • Reducing dependence on fossil fuels
  • Increasing the share of renewable energy in the power mix
  • Mitigating greenhouse gas emissions and combating climate change

These projects also serve as a model for future large-scale offshore wind farm connections around the globe.

DolWin 1 & 2: Offshore Wind Farm Specifications

DolWin 1 & 2: Offshore Wind Farm Specifications

While detailed technical specifications for DolWin 1 & 2 might not be publicly available, here's a table outlining some general specifications for offshore wind farms:

Project TypeOffshore Wind Farm (DolWin 1 & 2 are grid connection systems)
LocationNorth Sea, Germany (common for offshore wind farms in this region)
Capacity (total)Not publicly available (depends on connected wind farms)
Turbine Capacity (each)Typically 3-10 MW for modern offshore turbines
Number of TurbinesNot publicly available (depends on connected wind farms)
Water DepthTypically 20-50 meters for offshore wind farms
Foundation TypeUsually monopile or jacket foundations
Grid ConnectionHigh Voltage Direct Current (HVDC) (likely for DolWin 1 & 2)


  • The capacity values are estimates and can vary depending on the specific wind farm project.
  • This table provides a general overview. Specific details about DolWin 1 & 2 might be available on the developer's website or through official reports.

DolWin 1 & 2: High Voltage Direct Current Converter Platforms

DolWin 1 and 2 are not offshore wind farms themselves, but rather crucial players in the game of bringing clean energy ashore. They function as High Voltage Direct Current (HVDC) converter platforms, collecting electricity from offshore wind farms and transmitting it to the mainland grid. 

Here's a breakdown of their key features and the technology behind them:

FeatureDolWin 1DolWin 2
FunctionCollect electricity from offshore wind farms and transmit it to the mainland gridCollect electricity from offshore wind farms and transmit it to the mainland grid
Connected Wind FarmsBorkum Riffgrund 1 and Trianel wind farm BorkumGode Wind 1 and Nordsee One
Operational Since20152017
Offshore Converter PlatformJacket foundationInnovative floating platform (DolWin beta) anchored by gravity
Transmission Capacity900 MW900 MW
Households Powered (per year)Over 1 millionOver 1 million

Technology Table

TechnologyDescriptionDolWin 1 (source: [Wikipedia DolWin1 ON])DolWin 2 (source: [Wikipedia DolWin2 ON])
Converter TypeVoltage-Sourced Converter (VSC)LikelyLikely
Transmission CurrentHigh Voltage Direct Current (HVDC)ConfirmedConfirmed
Nominal Voltage±320 kV DC (typical for VSC HVDC)LikelyLikely
Cable Length135 kmConfirmedConfirmed
Platform DesignJacket foundation (conventional)Floating platform (DolWin beta)

Note: The information for converter type and nominal voltage for DolWin 1 & 2 are based on typical configurations for VSC HVDC systems and might need to be confirmed from official sources from TenneT or Hitachi Energy (formerly ABB).

DolWin 1 & 2: Offshore Wind Farm Specifications

DolWin 1 & 2: Offshore Wind Farm Grid Integration

DolWin 1 and DolWin 2 are High-Voltage Direct Current (HVDC) converter stations that play a crucial role in integrating offshore wind farms into the mainland grid. These stations are responsible for efficiently transmitting the electricity generated by the wind turbines to onshore locations.

Grid Integration Challenges

Large-scale offshore wind farms introduce unique challenges to grid integration. Some of these challenges include:

  • Variable Power Output: Wind is a variable resource, and the power output of an offshore wind farm can fluctuate significantly depending on wind speed. This variability can put a strain on the stability of the power grid.
  • Transmission Distance: Offshore wind farms are often located far from the shore, which necessitates long-distance transmission of electricity. Traditional AC transmission can suffer from power losses over long distances.

DolWin Solution

DolWin 1 and DolWin 2 utilize HVDC technology to address these challenges. Here's how:

  • HVDC Transmission: DolWin converter stations convert the AC electricity generated by the wind farm into DC electricity. DC transmission offers several advantages over AC transmission for long distances, including:

    • Lower power losses
    • Improved grid stability
    • Control over the flow of power
  • Power Conversion and Control: The converter stations are equipped with sophisticated controls that can regulate the power flow and ensure the stability of the grid. This allows for the efficient integration of variable wind power into the mainland grid.

Table: DolWin Project Specifications (indicative values)

Project NameDolWin 1 & 2
TypeHVDC Converter Stations
CapacityUp to 900 MW (each)
Voltage (AC)Offshore: 155 kV
Voltage (DC)± 320 kV
DistanceUp to 190 km (distance to shore)

Note: The table values are indicative and may vary depending on the specific project details.

By utilizing HVDC technology, DolWin 1 and DolWin 2 play a significant role in enabling the large-scale integration of offshore wind energy into the power grid. This contributes to a cleaner and more sustainable energy future.

DolWin 1 & 2: Offshore Wind Farm - Organization Support

DolWin 1 and 2 are not directly offshore wind farms themselves, but rather High Voltage Direct Current (HVDC) converter platforms that collect electricity from nearby offshore wind farms and transmit it to the mainland power grid.

Here's a table outlining the key organizations involved in DolWin 1 & 2:

TenneTGerman transmission system operator responsible for DolWin 1 & 2 projects, grid connection, and onshore converter stations.
ABBManufacturer of the converter technology used in the DolWin 1 & 2 platforms.
BoskalisContractor for the transport and installation of the DolWin 2 platform (including transport vessel, rock placement, and anchoring).
AibelEngineering, procurement, and construction (EPC) contractor for the DolWin 2 platform (in collaboration with ABB).

Additional Notes:

  • The wind farms that connect to DolWin 1 & 2 may have separate owners and operators.
  • Other companies may have been involved in various aspects of the projects, such as cable laying or substation construction.


The DolWin 1 & 2 projects involved a collaboration between various organizations with specialized expertise. TenneT, as the transmission system operator, spearheaded the project and ensured grid connection. ABB provided the core converter technology, while Boskalis and Aibel handled the transportation, installation, and construction of the DolWin 2 platform. This collaborative approach is typical of large-scale offshore wind farm projects, where different companies contribute their specific skills to ensure a successful outcome.

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