Copenhagen/Berlin - Today (23 May), the innovative interconnector concept Combined Grid Solution of electricity transmission system operators 50Hertz (Germany) and Energinet (Denmark) received the "Good Practice of the Year Award" of the Renewables Grid Initiative (RGI). At the award ceremony during the Energy Infrastructure Forum in Copenhagen, there was particular praise for the approach of connecting the power grids of two countries using the grid infrastructure of offshore wind farms and using this connection as efficiently as possible. The jury also referred to the potential of the concept for implementation in other off-shore projects as well. The idea could inspire meshed grids throughout Europe.
For the Combined Grid Solution, 50Hertz and Energinet laid submarine cables between the offshore substations of the German wind farm Baltic 2 off Rügen island and the Kriegers Flak wind farm in the Danish part of the Baltic Sea. Renewable energy generated by the wind turbines has priority and flows to Germany and Denmark as needed. Free capacity of the interconnector can be used to exchange electricity between the two countries. “The cross-border approach also turned out to be a success story with regard to the cooperation of both teams from 50Hertz and Energinet. This allowed us to gain new experience that will help us realise similar large projects in the future with the know-how we obtained from the Combined Grid Solution”, says Elke Kwapis, who manages the project at 50Hertz.
To enable the realisation of the connection, the planners at 50Hertz and Energinet had to overcome a challenge: the German and Danish alternating current grids are not synchronous and therefore cannot be interconnected directly. Although the grid frequency of 50 hertz is identical, it has a slightly different phase in both countries. The engineers and technicians solved this problem by means of a so-called back-to-back converter on the German side, which is currently being constructed on land in Bentwisch, near Rostock. This installation will transform alternating current with the Danish (northern) phase to direct current and then immediately into alternating current with the German (continental) phase. In order to control the entire system, a newly developed Master Controller for Interconnector Operation (MIO) will be in-stalled and operated by 50Hertz.
The Combined Grid Solution furthers the energy transition in Europe through improved integration of renewable energy and increases the security of the electrical system in Germany and Denmark. 50Hertz and Energinet entered into dialogue with the public from the very start to involve them in the project and as such achieved high local acceptance.
The Combined Grid Solution should be put into service in the third quarter of 2019. The investment for the project approaches 300 million Euros. The European Union supports the project in the scope of the European Energy Programme for Recovery (EEPR).
Background information: The Renewables Grid Initiative (RGI) is a dialogue platform of European non-governmental organisations and transmission system operators. RGI is committed to a transparent and eco-friendly development of the grid, needed for the growth and integration of renewable energy. The founding members include Germanwatch and the WWF as well as 50Hertz and TenneT. Since 2012, the "Good Practice of the Year Award" has been granted for innovations in the field of grid development. An independent jury of experts chose the winners in the categories "Communication and Participation", "Technology and Design" and "Environmental Protection". The Combined Grid Solution received the award in the technology category.
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More information about the project Combined Grid Solution