Transformer platform
A substation is a substation or substation that is installed on an offshore platform in the open sea. These structures are mainly used in offshore wind farms , but could also be used in future in connection with other marine power plants in remote locations.
Technical structure and function
The transformer platform serves to reduce the losses and the effort involved in transmitting electrical energy from the offshore wind farms to the mainland.
The individual wind turbines (WTs) in an offshore wind farm are usually divided into groups (clusters); the wind turbines in each cluster are connected to one another by submarine cables that are laid in a ring or in a radial pattern in the wind farm to the transformer station. A cable typically transmits a power of less than 30 MW; Large wind farms with several hundred megawatts of power therefore require a corresponding number of such cables. The station with the transformer on the platform serves as a collection point. In the station, the generated electricity is transformed from the park-internal voltage level, typically 26-33 kV, to the voltage level of the high-voltage network, typically in the range 100-220 kV. On the one hand, this reduces the electrical transmission losses on the way to the coast. On the other hand, the outgoing cables can transmit a significantly higher power due to the higher voltage, which reduces the number of cables to be laid to the mainland (or in the case of high-voltage direct current transmission (HVDC) to the converter station).
It is also possible to do without a transformer station or to build one on land. Such potential exceptions include locations close to the coast up to about 15 kilometers from the mainland, small wind farms with a few systems and an output of less than 100 MW or parks whose internal voltage level corresponds to the grid voltage at the feed-in point.
High-voltage direct current transmission (HVDC) is used for very large wind farms and / or locations remote from the coast with distances of more than 25 km (see also Offshore HVDC systems ). In this case, the converter station is housed on another platform near one or more offshore wind farms. The first system of this type in Germany is the " Borwin alpha " converter platform operated by the HVDC BorWin1 . Some modern offshore wind farms also use internal farm cabling with a transmission voltage of 66 kV, which is directly connected to the converter platform. In this way, the transformer platform can be dispensed with, which makes the grid connection cheaper.
Because of the limited space and the risk of corrosion from the salty sea air, the switchgear on transformer platforms is designed using encapsulated SF6 technology .
Further tasks
In addition to their electrotechnical function, transformer platforms often also serve as a base for construction, maintenance and overhaul work on the wind farm. They therefore often have service rooms and crew quarters for several dozen people. A helideck is usually available for the transport of material and personnel to and from the station, as well as the option of mooring with suppliers or other ships.
Web links
Individual evidence
- ↑ Dorman Wensky: Overview: Technologies for deriving the energy from offshore wind farms. (PDF) Presentation on the occasion of the dena technical discussion “Laying submarine cables to connect offshore wind farms to the grid in federal waterways”. (No longer available online.) ABB AG , March 2006, formerly in the original ; Retrieved October 5, 2011 . ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ^ Garrad Hassan and Partners: Offshore Wind Energy Technology . Report. EU project Concerted Action on Offshore Wind Energy in Europe (CA-OWEE), 2002 ( full text on offshorewindenergy.org [PDF]).
- ^ Wind farm design offshore: Electrical System. Wind Energy - The Facts, archived from the original on October 1, 2011 ; Retrieved September 22, 2011 .
- ↑ Tennet saves 200 million euros in offshore grid connection . In: IWR , May 7, 2019. Retrieved May 9, 2019.
