50hertz.com
50hertz.com
Suchen-Icon
  • DE
  • EN
  • Media
    • Media library
    • Contact
    • Press releases
    • Security of supply
  • Career
    • Job Offers
    • About 50Hertz
    • Application Procedure
    • Job subscription
    • Special-IT-Jobs
  • Investor Relations
  • Partners
    • Grid customers
      • Grid connection
      • Grid access
    • Balancing group customers
    • Market communication
    • System services
      • Utilisation before limitation
      • Grid losses
      • Grid reserve
    • Standard contracts
    • Suppliers
      • SAP Business Network
      • Frequently Asked Questions
      • Downloads
        • Principles
        • Previous versions of purchasing conditions
    • EEG registration
  • Company
    • Structure
      • Management
      • Supervisory Board
    • Roles
    • Business locations
    • Sustainability
      • CSR Portal
      • Occupational safety
      • Engagement
      • Governance
    • Innovation
    • Partnerships
      • Scientific Advisory & Project Board (SAPB)
    • History
    • Strategy
      • Future. Renewable
      • Future. Economic
      • Future. Digital
      • Future. Thoughtful
  • Grid
    • Grid developement
      • Onshore projects
        • 380 kV overhead line Pasewalk – Bertikow
        • 380-kV overhead line Güstrow – Parchim Süd – Perleberg
        • 380-kV overhead line Perleberg – Wolmirstedt
        • 380 kV overhead line Pulgar – Vieselbach
        • 380-kV Berlin diagonal power link
        • 380 kV overhead line "Nordring Berlin"
        • Third interconnector
        • Grid connection of the Jessen/Nord substation
        • Grid reinforcement of 380-kV high-voltage transmission line Röhrsdorf-Weida-Remptendorf
        • SuedOstLink
        • South-West Interconnector
        • Uckermark Line
        • Grid reinforcement Mecklar-Vieselbach
        • SuedOstLink Plus
        • Eulenberg substation
      • Offshore projects
        • Grid connection OST-6-1
        • Hansa PowerBridge
        • Ostwind 2
        • Kontek 400-KV Grid Connection
        • Ostwind 3
      • Interconnectors and phase shifters
      • Concluded projects
        • Ostwind 1
        • Combined Grid Solution
        • 380-kV line Bärwalde – Schmölln
        • 380 kV grid connection to the Förderstedt substation
        • Baltic 1
        • Baltic 2
        • Wind Bus Bar
      • Why expand the grid?
        • Frequently asked questions
        • 50Hertz Energy Transition Outlook 2035
      • Planning criteria
      • Planning and approval process
        • Grid Development Plan (GDP) and Federal Requirement Plan
        • Planning and licensing
        • Transparency and public participation
      • Compensations for municipalities
      • Projects of Common Interest (PCI)
      • BESTGRID
        • 50Hertz pilot project
        • Publications
      • compactLine
    • System control
      • Grid control
      • System balancing
      • Grid availability
      • Redispatch
    • Grid operations
    • MCCSNG
  • Market
    • European internal energy market
    • Grid usage and congestion management
      • Usage of interconnectors
      • Usage of 50Hertz grid
      • Congestion management international
      • Congestion management national
    • Balancing energy
    • Market roles
    • EEG
  • Transparency
    • Grid Data
      • Installed capacity
        • Wind power
        • Photovoltaics
      • Production & grid feed-in
        • Production
        • Grid feed-in
        • Wind power
        • Photovoltaics
      • Disclosure of EEG data
        • Annual EEG bill
        • Publications on EEG balancing group
      • Congestion management
        • Measures as per § 13 para. 1 EnWG (Conventional power plants)
        • Measures as per § 13 Abs. 1 EnWG (EE and VNB)
        • Measures as per § 13 para. 2 EnWG
        • Commercial transactions to balance the redispatch balancing group
        • Archive Measures as per § 13 EnWG
        • Redispatch Calculator SWKL
        • Outage and Planning
      • Balancing
        • Control reserve (capacity provision)
        • Control energy (activated balance energy)
        • Archive control energy
    • Positions and Contact
  • Grid developement
    • Onshore projects
    • Offshore projects
    • Interconnectors and phase shifters
    • Concluded projects
      • Ostwind 1
      • Combined Grid Solution
      • 380-kV line Bärwalde – Schmölln
      • 380 kV grid connection to the Förderstedt substation
      • Baltic 1
      • Baltic 2
      • Wind Bus Bar
    • Why expand the grid?
    • Planning criteria
    • Planning and approval process
    • Compensations for municipalities
    • Projects of Common Interest (PCI)
    • BESTGRID
    • compactLine
  • System control
  • Grid operations
  • MCCSNG
Home/Grid/Grid developement/Concluded projects/Combined Grid Solution

Kriegers Flak – Combined Grid Solution

Together with its project partner, the Danish transmission system operator Energinet, 50Hertz has planned the first offshore interconnector in the Baltic Sea by linking the two national offshore wind farm connections.

The so-called Kriegers Flak Combined Grid Solution (CGS) connects the Danish region of Zealand with the German state of Mecklenburg-Western Pomerania. The transfer capacity is 400 megawatts (MW). Construction was rolled out end of 2016/beginning of 2017. Commissioning/Energisation and start of test phase “Trial Operation” took place in December 2020. During Energisation the German and Danish grid will be connected together.

News

CONTACT

Yvonne Post

Public participation
  • Tel:
    +49 30 5150-3093
  • E-Mail:
    yvonne.post@50hertz.com

Germany currently operates two offshore wind farms in the Baltic Sea, Baltic 1 (48 MW) and Baltic 2 (288 MW). Denmark built the offshore wind farm Kriegers Flak (600 MW). The Kriegers Flak (Denmark) and Baltic 2 (Germany) wind farms are less than 30 kilometres apart. The interconnector was established by connecting both wind farms by means of two submarine cables.


The frequencies of the Danish and German transmission systems use a slightly different phase. That is why they need to be matched at the interface. This is enabled by means of two serial voltage source converters (VSC). A converter transforms the alternating current (AC) from the Nordic interconnected system to direct current (DC). Another converter transforms this direct current back to alternating current - only now adapted to the synchronous area of continental Europe.


This so-called back-to-back converter has been installed in Bentwisch, near Rostock. The construction of the double converter on land is more favourable and allows easier maintenance than the construction and operation of the installation on an offshore platform. This was provided for in the original concept.


Due to the different voltage levels of the Danish and German offshore wind farms (150 to 220 kilovolt), a transformer is also required. However, this has been installed on the Danish offshore platforms.

Schedule
Approval procedure:until the first half of 2017
Specification of the technical design:January 2010 – September 2014
Call for tenders and award of contract:October 2014 – June 2016
Production of the installations:January 2016 – June 2018
Construction, installation and testing:January 2017 – Q1 2020
Commissioning and trial run:December 2020

Status Combined Grid Solution

Necessity

In order to implement the energy transition, the infrastructure of the German and also the European energy industry needs to be adapted. In the future, ever more flexible installations, interconnectors as well as storage units will be required in order to balance the fluctuations in the production of energy by wind turbines and solar panels.

Especially the transmission grids play a key role in this regard: extra high-voltage lines form the backbone of the power supply in Germany and Europe. Increasingly, electricity is generated where demand is highest, but where there are optimal climatic and geological conditions.

At the same time, however, the high level of security of supply and the grid stability should be guaranteed. In order to ensure both, electricity exchange between neighbours is also a tried and tested method. The Combined Grid Solution - Kriegers Flak functions exactly as such a bridge between Germany and Denmark and ensure the additional exchange of several hundreds of megawatts in electricity between our countries. As a result, the interconnector will further increase the security of supply of the German transmission grid. Moreover, the new connection facilitates the integration of regionally generated renewable energy in Germany and in eastern Denmark and thus increases its consumption.

Grid expansion projects such as CGS close the gaps in the European interconnected grid and contribute to the further development of the common European energy market. The European Commission has therefore classified CGS as a project of common interest (PCI). The project was financially supported by the European Energy Programme for Recovery (EEPR).

That's how the CGS will look like.
Technology and Innovation

The Combined Grid Solution is a hybrid system. On the one hand, it serves as the grid connection for the offshore wind farms, on the other hand it connects the transmission grids of Denmark and Germany and, thus, allows for the transnational exchange of electricity. In case of strong wind, the full capacity of submarine cables can be used to feed the wind power generated offshore into two grids via one single system. If there is relatively little wind on the Baltic Sea, however, the remaining capacity can still be used for the exchange of electricity between the two countries. Consequently, the platform and submarine cables are optimally used, regardless of the wind on the high seas. This system does not yet exist anywhere else in the world.

In order to control this complex system, a newly developed Master Controller for Interconnector Operation (MIO) with the latest information technology has been installed in the Transmission Control Centre in Berlin/Neuenhagen.

The Master Controller acts as the ‘brain’ of the entire system. It calculates the available capacity of the interconnector (wind forecasts), prevents overload by controlling the converter and/or the wind farm, maximises the feed-in from the wind farms through active system control (936 MW are possible), controls the exchange of electricity between the grids of both countries by means of the converter. In this way, the infrastructure of the wind farm connections and the interconnector, mainly submarine cables, can be utilised to 100 per cent which also lowers the prices for the consumer.

Schematic representation of Combined Grid Solution – Kriegers Flak

The extension of one of the two Kriegers Flak substation platforms at sea was required for the interconnector project CGS. The cables from all the wind turbines in the wind farm are connected in the transformer station at the transformer platforms. The voltage is transformed from 33 to 150 or 220 kilovolts (kV) for efficient further transport.

Operating a transformer platform at sea is very challenging. Since sea air is very humid, the hall of the transformer platform must be particularly well air-conditioned and dehumidified. This creates almost the same climatic conditions as on land. Offshore transformer platforms are constructed in a similar way to gas-insulated switching stations on land. The transformer platform is additionally reinforced so that it is well prepared for the harsh weather conditions at sea.

The extension of one of the transformer platforms with the additional transformer serves as an interface between the German 150 kV grid and the Danish 220 kV grid.

Schematic representation of the switching platform
Project partnership with Energinet and legal foundations

Together with the Danish transmission system operator Energinet, 50Hertz implements the first offshore interconnector in the Baltic Sea connecting two national offshore wind farm connections. In 2017, both project partners started the construction work.

The legal basis for Combined Grid Solution - Kriegers Flak (CGS) is the Federal Requirements Plan Act (BBPIG) of 31 December 2015. In the Federal Requirements Plan Act, the project is listed as number 29. The basis for the Federal Requirements Plan is the confirmed Grid Development Plan for Electricity for 2024 which was established in 2014. This plan is based on a ten-year period for which the national Grid Development Plan (GDP) was developed and subject to public debate - see also netzentwicklungsplan.de or netzausbau.de.

Especially the balancing function for production and consumption across state borders is new and brings Europe even closer together in the future. The conversion of the electricity grids in the context of the energy transition has reached the European level and will be decisive for the security of supply in Europe.

Information and Materials

  • FURTHER INFORMATION
Comprehensive view

Newsletter

Keep up to date with the latest developments

SUBSCRIBE HERE
Questions? We are here to answer

Citizens‘ Telephone

0800-58952472
Monday-Friday: 8AM-8PM
Free of charge from the German landline and mobile network

Project 5 within the SuedOstLink as a "project of common interest" (PCI) of the European Union is crucial for the further improvement of security of supply and the expansion of renewable energies and receives funding.


The sole responsibility for the content of this website lies with the authors. It does not necessarily reflect the opinion of the European Union. Neither the EACI nor the European Commission accept any responsibility for any use which may be made of the information contained therein.


Further information on EU funding for our projects can be found here:

  • ​PROJECTS OF COMMON INTEREST (PCI) ​​​
  • Contact
  • Imprint
  • Data protection
  • Newsletter
  • Sitemap
  • per E-Mail teilen auf Facebook teilen auf Twitter teilen
Login