Offshore HVDC systems

Offshore HVDC systems are systems for high-voltage direct current transmission of the electricity generated from offshore wind farms to land. They are used for low-loss electrical energy transmission and have so far only been used in Germany ( North Sea ) for this purpose , as here offshore wind farms (OWP), in contrast to Great Britain and Denmark, are usually built outside of the field of vision of the coast, and therefore have to cover greater distances are. It is to be expected that this technology will also be used in other countries if the locations close to the coast are occupied here. Outside of Germany are offshore HVDC systems and for the supply of oil and gas platforms in use, for example Troll A .

Structure and functionality

Since the distances to the coast are 30 to 120 km, depending on the location of the wind farm, the three-phase transmission in the submarine cables results in large losses due to the capacitance . For this reason, so-called converter platforms are set up near the offshore wind farms - usually by the responsible transmission system operator - on which the three-phase alternating current is converted into direct current . Offshore HVDC systems are complex to set up, but reduce the transmission losses of the cables over the great distance considerably, since the capacitance of the submarine cable is irrelevant for direct current .

HVDC land station Büttel , view of the converter station

Offshore HVDC systems consist of a converter station built on the platform to convert the three-phase current into direct current, the HVDC submarine cable and a converter station on land. The latter converts the electricity back into three-phase current and enables it to be fed into the network . In the offshore sector, this HVDC technology was new territory, only a few companies ( Siemens , ABB , Alstom ) have had experience with this technology.

The Nordic Yards shipyards in Mecklenburg-Western Pomerania built several offshore HVDC platforms that were equipped by Siemens. Depending on the output, the fully equipped HVDC platforms weigh 2,500 to 10,000 tons.

The effort involved in planning and setting up offshore wind energy as a complete system is more complex and time-consuming than the previous HVDC systems on land. This aspect was underestimated by everyone involved, including the energy supply companies and the politicians of the states and the federal government. Therefore, the infrastructure for power transmission on land is not on schedule and the expansion of offshore wind farms is stalling due to late connection dates and offshore HVDC systems.

HVDC systems in the German Bight (bold black lines)

Offshore HVDC systems in the German Bight of the North Sea

Most of the German offshore wind farms in the North Sea are located in the German Exclusive Economic Zone (EEZ), which is at least twelve nautical miles from the coast. The wind farms consist of 40 to 120 wind turbines, the internal cable network in the wind farm (33 kV) and a transformer platform to increase the voltage to 150 to 320 kV. The prevailing water depths of 20 to 40 m here require foundations made of steel pipes ( monopiles ), tripods or half-timbered structures ( jackets ) with a weight of up to 900 t to ensure that the wind turbines stand securely . Due to the large distances between the wind farms and the onshore feed-in stations, HVDC systems (offshore high-voltage direct current transmission ) are used for low-loss energy transmission .

The HVDC BorWin 1 is the world's first high-voltage direct current transmission connection for connecting offshore structures. It is used to connect the first commercial German offshore wind farm " BARD Offshore 1 " to the German high-voltage network and thus also to the European network .

The offshore HVDC plants in the German Bight of the North Sea are grouped together.

Cluster	Surname	Offshore platform	Network operator	Substation on land	Wind farm (s)	Length of submarine cable	Length of underground cable	tension	Transmission capacity	status	Commissioning (Year)	Manufacturer	Remarks
BorWin ( Borkum )	NOR-6-1 BorWin1	BorWin alpha	Tennet TSO	Hall (at hall )	BARD Offshore 1 (400 MW)	125 km	75 km	150 kV	400 MW	in operation	2013	FIG
	NOR-6-2 BorWin2	BorWin beta	Tennet TSO		Veja Mate (400 MW) Albatros (116.8 MW) German Bight (269 MW)	125 km	75 km	300 kV	800 MW	in operation	2015	Siemens
	NOR-8-1 BorWin3	BorWin gamma	Tennet TSO	Emden / East (near Borssum )	Global Tech I (400 MW) High Seas (500 MW)	132 km	28 km	320 kV	900 MW	in operation	2019	Siemens, Petrofac
	NOR-6-3 BorWin4	BorWin delta	Amprion	Hanekenfähr (at Emsland NPP )		130 km	130 km	320 kV	900 MW	in planning	(2029)	NN	Construction contract planned for 2024
	NOR-7-1 BorWin5	BorWin epsilon	Tennet TSO	Garrel / Ost (near Cloppenburg )	He Dreiht (900 MW)	120 km	110 km	320 kV	900 MW	planned	(2025)	Siemens, Dragados	August 11, 2020: Construction contract awarded
	NOR-7-2 BorWin6	BorWin kappa	Tennet TSO	Büttel (near Büttel )		180 km	30 km	320 kV	930 MW	in planning	(2027)	NN	Construction contract planned for 2022
DolWin ( Dollart )	NOR-2-2 DolWin1	DolWin alpha	Tennet TSO	Dörpen / West (near Heede )	Trianel Windpark Borkum  1 (200 MW) Trianel Windpark Borkum  2 (203 MW) Borkum Riffgrund 1 (314 MW)	75 km	90 km	320 kV	800 MW	in operation	2015	FIG
	NOR-3-1 DolWin2	DolWin beta	Tennet TSO		Gode ​​Wind 1 (330 MW) Gode ​​Wind 2 (252 MW) Nordsee One (332 MW)	45 km	90 km	320 kV	916 MW	in operation	2017	Aibel, FIG
	NOR-2-3 DolWin3	DolWin gamma	Tennet TSO		Borkum Riffgrund 2 (448 MW) Merkur (396 MW)	83 km	79 km	320 kV	900 MW	in operation	2019	General Electric
	NOR-3-2 DolWin4	DolWin delta	Amprion	Hanekenfähr (at Emsland NPP )		60 km	130 km	320 kV	900 MW	in planning	(2028)	NN	Construction contract planned for 2023
	NOR-1-1 DolWin5	DolWin epsilon	Tennet TSO	Emden / East (near Borssum )	Borkum Riffgrund 3 (900 MW)	100 km	30 km		900 MW	planned	(2024)	Aibel, ABB , Keppel FELS	May 7, 2019: Construction contract awarded
	NOR-3-3 DolWin6	DolWin kappa	Tennet TSO		Gode ​​Wind 3 (242 MW)	45 km	45 km	320 kV	900 MW	under construction	(2023)	Siemens, Dragados	July 17, 2017: Construction contract awarded
HelWin ( Helgoland )	NOR-4-1 HelWin1	HelWin alpha	Tennet TSO	Büttel (near Büttel )	Sea wind south / east (288 MW) North Sea east (295 MW)	85 km	45 km	250 kV	576 MW	in operation	2015	Siemens
	NOR-4-2 HelWin2	HelWin beta	Tennet TSO		Amrumbank West (302 MW) Kaskasi (342 MW)	85 km	45 km	320 kV	690 MW	in operation	2015	Siemens
SylWin ( Sylt )	NOR-5-1 SylWin1	SylWin alpha	Tennet TSO		Butendiek (288 MW) DanTysk (288 MW) Sandbank 1 (288 MW)	160 km	45 km	320 kV	864 MW	in operation	2015	Siemens
	SylWin2	SylWin beta	Tennet TSO						536 MW	Abandoned planning	(2025)	NN	No wind farm authorized to connect
BalWin ( Baltrum )	NOR-9-1 BalWin1	BalWin alpha	Tennet TSO	Unterweser (at Unterweser NPP )		140 km	80 km	525 kV	2,000 MW	in planning	(2029)	NN	Construction contract planned for 2024
	NOR-9-2 BalWin2		Amprion	Search area Ibbenbüren / Mettingen / Westerkappeln						unconfirmed		NN
	NOR-10-2 BalWin3		Tennet TSO	Heide / West (near Heide )						unconfirmed		NN
	NOR-10-1 BalWin4		Tennet TSO	Unterweser (at Unterweser NPP )		150 km	80 km	525 kV	1,700 MW	in planning	(2030)	NN	Construction contract planned for 2025
LanWin ( Langeoog )	NOR-12-1 LanWin1		Tennet TSO	Wilhelmshaven 2 (near Wilhelmshaven )		170 km	50 km	525 kV	2,000 MW	in planning	(2030)	NN
	NOR-12-2 LanWin2		Amprion	Wehrendorf (near Wehrendorf )						unconfirmed		NN
	NOR-11-1 LanWin3			Westerkappeln (near Westerkappeln )		160 km	160 km	525 kV	2,000 MW	in planning	(after 2030)	NN
	NOR-11-2 LanWin4			Wehrendorf (near Wehrendorf )		170 km	160 km	525 kV	2,000 MW	in planning	(after 2030)	NN
	NOR-13-1 LanWin5		Tennet TSO	Heide / West (near Heide )				525 kV	2,000 MW	in planning	(after 2030)	NN

Source: Network development plan of the transmission system operator , confirmed by the Federal Network Agency .

See also

• List of switchgear in the extra high voltage network in Germany
• Association of European Transmission System Operators
• Marine thermal power plant (offshore section)

Web links

• Electricity network development plan
• Netzausbau.de

literature

• Andreas Rosponi, Reiner Klatte, Klaas Oltmann, Jan Henning Günther: The MOAB platform concept and its application for transformer stations within offshore wind farms , design examples and plans, yearbook of the Schiffbautechnische Gesellschaft 2010

Individual evidence

1. ↑ TenneT BorWin1. Retrieved May 7, 2019 . 
2. ^ ABB BorWin1. Retrieved May 7, 2019 . 
3. ↑ TenneT BorWin2. Retrieved May 7, 2019 . 
4. ↑ TenneT BorWin3. Retrieved May 7, 2019 . 
5. ↑ Michael Müller: 12,000 tons for the energy transition. In: Daily port report of April 30, 2014, p. 1
6. ↑ Sariana Kunze: TenneT awards major order for North Sea network connection. Vogel Communications Group , accessed April 24, 2014 . 
7. ↑ TenneT BorWin5. Retrieved August 16, 2020 . 
8. ↑ Tennet significantly reduces costs with BorWin5 offshore connection. Retrieved August 11, 2020 . 
9. ↑ TenneT DolWin1. Retrieved May 7, 2019 . 
10. ↑ ABB DolWin1. Retrieved May 7, 2019 . 
11. ↑ TenneT DolWin2. Retrieved May 7, 2019 . 
12. ↑ ABB DolWin2. Retrieved May 7, 2019 . 
13. ↑ TenneT DolWin3. Retrieved May 7, 2019 . 
14. ↑ Claus Gorgs: GE chases Siemens in offshore wind power - Germany's floating socket. Manager Magazin , accessed July 19, 2017 . 
15. ↑ TenneT DolWin5. Retrieved August 29, 2019 . 
16. ↑ Tennet places orders for DolWin5 and emphasizes cost reductions in offshore network connections. Retrieved May 7, 2019 . 
17. ↑ TenneT DolWin6. Retrieved May 7, 2019 . 
18. ↑ Network connection DolWin6 of the offshore wind turbine DolWin kappa by means of a 600 kV direct current line. Retrieved July 30, 2017 . 
19. ↑ Tennet awards Siemens the contract for DolWin6. Retrieved July 18, 2017 . 
20. ↑ TenneT HelWin1. Retrieved May 7, 2019 . 
21. ↑ TenneT HelWin2. Retrieved May 7, 2019 . 
22. ↑ TenneT SylWin1. Retrieved May 7, 2019 . 
23. ↑ Confirmation of the electricity network development plan for the target year 2030. (PDF) Federal Network Agency , December 2019, accessed on January 20, 2020 .