Cross-Skagerak
Encyclopedia
Cross-Skagerrak is the name of an high-voltage direct current
(HVDC) transmission facility between Tjele (Denmark
) and Kristiansand
(Norway
). It is owned and operated by Statnett
in Norway, and Energinet.dk
in Denmark.
For such a long submarine cable, an AC transmission scheme would not be feasible since too much of the cable's capacity would be consumed by the capacitance
of the cable itself.
valves. When installed this underwater cable was the world's longest and deepest underwater HVDC power cable. The cable, manufactured by Alcatel
, is laid in a maximum water depth of 530 metres (1,738.8 ft).
Both cables have a capacity of 250 MW at 250 kV.
land cable on the Danish side is approximately 90 kilometres (55.9 mi), while the 137 kilometres (85.1 mi) subsea cable and the 12 kilometres (7.5 mi) Norwegian land cable is to be made by Nexans
for 638 million DKK. Converter stations will be built by ABB, as for Skagerak 1–3. The combined budget is 2.8-3.2 billion DKK.
The technology used will be VSC, capable of black start
. Although thyristor-based converters have a loss of only 0.7%, the IGBTs of VSC get close with a loss of 0.8 to 1%. Skagerrak 1 and 2 currently use Skagerrak 3 as a return cable, but 1 and 2 will be coupled so that Skagerrak 4 can use number 3 for returns.
Underground cable in Denmark
Overhead line in Norway
Electrode line in Norway
High-voltage direct current
A high-voltage, direct current electric power transmission system uses direct current for the bulk transmission of electrical power, in contrast with the more common alternating current systems. For long-distance transmission, HVDC systems may be less expensive and suffer lower electrical losses...
(HVDC) transmission facility between Tjele (Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
) and Kristiansand
Kristiansand
-History:As indicated by archeological findings in the city, the Kristiansand area has been settled at least since 400 AD. A royal farm is known to have been situated on Oddernes as early as 800, and the first church was built around 1040...
(Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
). It is owned and operated by Statnett
Statnett
Statnett is a Norwegian state owned enterprise responsible for owning, operating and constructing the stem power grid in Norway. The company has its headquarters in Oslo, Norway....
in Norway, and Energinet.dk
Energinet.dk
Energinet.dk is the Danish national transmission system operator for electricity and natural gas. It is an independent public enterprise owned by the Danish state under the Ministry of Climate and Energy...
in Denmark.
Technical features
The 240 kilometres (149.1 mi) Cross-Skagerrak 1–3 scheme consists of a 113 kilometres (70.2 mi) overhead line and a 127 kilometres (78.9 mi) underwater cable. It has a capacity of 1,050 megawatts (MW). Both land parts in Denmark and in Norway uses overhead lines from the cable landing point to the converter stations. The towers were originally constructed for four poles, but were rebuilt for three conductors (three poles) when Skagerrak 3 was established. Near Aggesund HVDC Cross-Skagerrak crosses Aggesund strait overhead on 70 metres (229.7 ft) towers with a 470 metres (1,542 ft) span.For such a long submarine cable, an AC transmission scheme would not be feasible since too much of the cable's capacity would be consumed by the capacitance
Capacitance
In electromagnetism and electronics, capacitance is the ability of a capacitor to store energy in an electric field. Capacitance is also a measure of the amount of electric potential energy stored for a given electric potential. A common form of energy storage device is a parallel-plate capacitor...
of the cable itself.
Skagerrak 1 and 2
Cross-Skagerrak went in service in 1977 as a bipolar HVDC scheme. This facility was built with thyristorThyristor
A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased .Some sources define silicon controlled rectifiers and...
valves. When installed this underwater cable was the world's longest and deepest underwater HVDC power cable. The cable, manufactured by Alcatel
Alcatel
Alcatel Mobile Phones is a brand of mobile handsets. It was established in 2004 as a joint venture between Alcatel-Lucent of France and TCL Communication of China....
, is laid in a maximum water depth of 530 metres (1,738.8 ft).
Both cables have a capacity of 250 MW at 250 kV.
Skagerrak 3
In 1993 the scheme was extended by HVDC Cross-Skagerrak 3. Cross-Skagerrak 3 is a monopolar line for a voltage of 350 kV with a capacity of 440 MW at 350 kV. In installing Cross-Skagerrak 3, the old poles Cross-Skagerrak 1 and Cross-Skagerrak 2 were converted to monopolar HVDC schemes, which run with opposite polarity to Cross-Skagerrak 3.Skagerrak 4
In November 2009, Statnett and Energinet.dk signed the agreement to construct Skagerrak 4. Capacity of Skagerrak 4 will be approximately 700 MW, and it is expected to be operational by 2014. As for the existing Skagerrak 1-3, the grid connection points will be Kristiansand and Tjele. Differently from Skagerrak 1–3, for Skagerrak 4 a cable solution is chosen for the complete route length. The 300 million DKK PrysmianPrysmian
Prysmian is an Italian-based multinational corporation headquartered in Milan and listed on the Milan Stock Exchange, manufacturing and laying cables for the energy and telecommunications sectors, it's the market leader, also thanks to the acquisition of Draka Holding...
land cable on the Danish side is approximately 90 kilometres (55.9 mi), while the 137 kilometres (85.1 mi) subsea cable and the 12 kilometres (7.5 mi) Norwegian land cable is to be made by Nexans
Nexans
Nexans S.A. is a French company which manufactures copper and optical fiber cable products for the infrastructure, industrial and construction markets. It is the world's largest manufacturer of cables. It has an industrial presence in nearly 40 countries, over 23,000 employees and sales of around...
for 638 million DKK. Converter stations will be built by ABB, as for Skagerak 1–3. The combined budget is 2.8-3.2 billion DKK.
The technology used will be VSC, capable of black start
Black start
A black start is the process of restoring a power station to operation without relying on the external electric power transmission network.Normally, the electric power used within the plant is provided from the station's own generators...
. Although thyristor-based converters have a loss of only 0.7%, the IGBTs of VSC get close with a loss of 0.8 to 1%. Skagerrak 1 and 2 currently use Skagerrak 3 as a return cable, but 1 and 2 will be coupled so that Skagerrak 4 can use number 3 for returns.
Sites
| Site | Coordinates |
|---|---|
| Tjele HVDC Static Inverter | 56°28′44"N 9°34′1"E |
| Denmark Overhead Electrode Line Terminal | 56°37′16"N 9°28′32"E |
| Aggesund Crossing Tower South | 57°0′0"N 9°18′7"E |
| Aggesund Crossing Tower North | 57°0′12"N 9°17′50"E |
| Danish Cable Terminal | 57°7′34"N 9°3′58"E |
| Norway Cable Terminal | 58°7′45"N 8°10′3"E |
| Norway Electrode Line Terminal | 58°10′02"N 8°15′56"E |
| Norway Electrode Line Branch | 58°11′10"N 8°9′24"E |
| Kristiansand HVDC Static Inverter | 58°15′36"N 7°53′55"E |
Waypoints
Overhead line in DenmarkUnderground cable in Denmark
Overhead line in Norway
Electrode line in Norway
See also
- Baltic CableBaltic CableThe Baltic Cable is a HVDC power line running beneath the Baltic Sea that interconnects the electric power grids of Germany and Sweden.The Baltic Cable uses a transmission voltage of 450 kV – the highest operating voltage for energy transmission in Germany...
- KontekKontekThe Kontek is a 170 kilometer long, monopolar 400kV DC-cable for the interconnection of the German power grid with the electricity grid of the Danish island Sealand. The name comes from "continent" and the name of the former Danish power transmission company "Elkraft", which operated the power grid...
- Konti-SkanKonti-SkanKonti–Skan is the name of high-voltage direct-current transmission line between Denmark and Sweden.-Technical description:...
- NORD.LINKNORD.LINKNORD.LINK is a proposed subsea HVDC power cable between Norway and Germany. The feasibility study was completed at the end of 2008. If constructed, the capacity of NORD.LINK is expected to be 1,400 MW. It is estimated to cost €1.4 billion. The interconnector is planned installed between...
- NorNedNorNedNorNed is a long HVDC submarine power cable between Feda in Norway and the seaport of Eemshaven in the Netherlands, which interconnects both countries' electricity grids. It is the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the...
- Scotland-Norway interconnector
External links
- Description of Cross-Skagerrak 3
- http://web.archive.org/web/20051115122606/www.transmission.bpa.gov/cigresc14/Compendium/Skagerr%20Pictures.pdf