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50Hertz, the transmission system operator for the northeast of Germany, is responsible for bringing all wind power generated in the Baltic Sea to the onshore power grid via submarine cables. We build the required infrastructure, lay the submarine cables and operate these systems.
The Offshore department and the regional centre responsible for the Baltic Sea as well as the are located in Güstrow. The colleagues here are responsible for the day to day operation and maintenance of the offshore technology and work closely with the Offshore Projects department of the 50Hertz headquarters in Berlin where the construction of new plants is managed.
The first commercial offshore wind farm that was put into operation in Germany was Baltic 1 in the Baltic Sea (May 2011). The wind farm is located approximately 15 kilometres north of the Fischland-Darß-Zingst peninsula. At the Bentwisch substation near Rostock, 50Hertz connected this wind farm to the onshore power grid by means of a 150 kV submarine cable connection.
In the meantime, 50Hertz has started additional projects because an entire series of offshore wind farms with a total capacity of more than 3,500 megawatts are planned off the German Baltic Sea coast. This corresponds to about three and a half large conventional power plants.
For example, 50Hertz already connected the neighbouring Baltic 2 wind farm in 2015. Meanwhile, works are progressing well for the connection of the Ostwind 1 wind farm areal (with the offshore wind farms Wikinger and Arkona-Becken Südost https://www.50hertz.com/en/Grid-Extension/Offshore-projects/Projects/Ostwind-1) in the Cluster Westlich Adlergrund (CWA). We currently expect our connection works to be ready by 2019.
The electricity from the entire Cluster Westlich Adlergrund (CWA) will be transported from offshore substation Andalucia to the onshore substation in Lubmin by a 220 kV submarine cable over a distance of approx. 90 kilometres.
You can read more about the subject in our bilingual PDF brochure ‘From the sea to your power socket’.
The realisation of 50Hertz’s currently largest investment project started in 2016.
The 50Hertz grid area is connected to adjacent transmission systems in the framework of the European interconnected grid. This enables system-stabilising electricity flows across grid borders. 50Hertz is also active in the Baltic Sea within this framework. From 1994 to 1996, a 400 kV high voltage direct current (HVDC) connection to the Danish transmission grid was already installed over a distance of 165 kilometres: Kontek is connected to the German transmission system at the Bentwisch substation. The decision for direct current was made because the power grids in northern and continental Europe use alternating current of the same frequency with a slightly shifted phase. Direct current technology makes the connection possible.
The connection of offshore wind farms Baltic 1 and 2 should be used to establish an additional connection to the Danish transmission system. To this end, two submarine cables are laid between Baltic 2 and the Danish wind farm Kriegers Flak. This project is called ‘Kriegers Flak Combined Grid Solution’ (KG CGS). The preliminary works such as locating and clearing unexploded ordnance, have begun. Furthermore, the phase shift between the northern and continental European power grids mentioned earlier also requires a special solution for this project: in the future, the alternating current cables with which wind farms Baltic 1 and 2 are connected to the Bentwisch substation will be operated with the northern European phase. At the substation, the differently phased alternating currents will then be transformed to direct current. A double or back-to-back converter makes the connection possible. The construction works for this installation began in 2017.
Another connection, this time to the Swedish transmission system, is planned and, according to the current planning should be put into operation in 2025/26. This project, called Hansa PowerBridge, concerns a 300-kilometre direct current line through the Baltic Sea between Güstrow and Hurva in the south of Sweden.
Read more about it on our page Offshore projects.
The development of offshore wind farms in the Baltic Sea by 50Hertz will further increase the share of renewable energy in the company’s power grid. The input of electricity from renewable energy sources, until now mainly from onshore wind turbines, already reaches peak values that are the highest in the world.
This makes 50Hertz a much-noticed protagonist in the technical development of transmission grids and a respected partner in the design of functioning electricity markets. Why? As renewable energy is volatile and its use cannot be reliably planned because of natural causes. This represents a big challenge for the management of power grids which stability is based on the balance between the production and consumption of electrical energy due to the laws of physics.
Offshore fitness covers the health prerequisites for working offshore. They are checked by our company doctor according to the standards laid down in the guidelines setting out the occupational health and fitness requirements for employees on offshore wind turbines and offshore installations which was developed by the Association of the Scientific Medical Societies in Germany (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V., AWMF).