high-voltage direct current
A high-voltage direct current (HVDC) electric power transmission system uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages betwe ...
submarine power cable
A submarine power cable is a transmission cable for carrying electric power below the surface of the water.Feda, Norway and the seaport of Eemshaven in the
Netherlands
, Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
, which interconnects both countries'
electrical grid
An electrical grid (or electricity network) is an interconnected network for electricity delivery from producers to consumers. Electrical grids consist of power stations, electrical substations to step voltage up or down, electric power tran ...
s. It was once the longest submarine power cable in the world. Budgeted at €550 million, and completed at a cost of €600m, the NorNed cable is a bipolar HVDC link with a voltage of ±450 kV and a capacity of 700 MW. NorNed is a joint project of the Norwegian transmission system operatorStatnett and its Dutch counterpart TenneT. The cable system itself and the two converter stations were produced by ABB.
History
Installation of the first sections started in early 2006 and the final section was laid by the end of 2007. On the Dutch shore, TenneT has connected the cable to the 380 kV Dutch high‑voltage grid. In Feda, Statnett has done the same for the 300 kV Norwegian transmission grid. Commercial operation started on 5 May 2008 with a capacity auction. The first commercial power transfer took place on 6 May 2008.
After two months of operation, the cable generated revenues of approximately €50 million. In the business case drawn up for the NorNed cable, annual revenues were estimated at €64 million.
NorNed has been included in European Market Coupling Company operations as of 12 January 2011. The internal grid in Norway is sometimes not capable of handling enough power for NorNed and Cross-Skagerrak, and capacity for these cables is then artificially limited.
The cable had a fault in 2011, causing 7 weeks out of operation.
A fault was discovered in May 2022, causing a shutdown of operations. Operations are expected to resume in October 2022.
Technology
Although classed as a "bipolar" HVDC scheme, the NorNed scheme is unusual for a Line-Commutated (
thyristor
A thyristor (, from a combination of Greek language ''θύρα'', meaning "door" or "valve", and ''transistor'' ) is a solid-state semiconductor device which can be thought of as being a highly robust and switchable diode, allowing the passage ...
-based) HVDC scheme since there is just one 12-pulse converter at each end of the scheme, midpoint-grounded at Eemshaven. With voltage-source converter-based HVDC systems, this arrangement with the two high voltage cables at equal and opposite voltages but only a single converter at each end is referred to as a ''Symmetrical monopole''.
Consequently, with a DC voltage of ±450 kV, the converter for the NorNed project has a terminal to terminal DC voltage rating of 900 kV, making it (as of 2012) the highest voltage rating of any HVDC converter in the world. The connection has a loss of 4.2% (95.8% efficiency).
Sites
Trading mechanism
NorNed is the first power link between the Nordic electrical transmission system Nordel and the continent that is planned to be open to the power market. The main trading over the link is presumed to be one day ahead spot market trading based on the price difference between the markets. In spite of quite equal average spot market prices, the hour-by-hour differences are quite significant most of the time. The way the power exchanges will be compensated was to be agreed, and the direct net income from the trade is to be shared 50/50 between TenneT and Statnett.
COBRAcable
COBRAcable (''COpenhagen-BRussels-Amsterdam cable'') is a ±320 kV, 700 MW High-voltage direct current, HVDC submarine power cable pair between Eemshaven, the Netherlands and Endrup near Esbjerg, Denmark. The cable is jointly owned by E ...
NorGer
NorGer was one of two planned electricity cables between Germany and Norway. The other proposed project was NordLink, which Statnett decided to proceed with in 2015, and NorGer was cancelled.
Description
NorGer interconnector will start in Tonst ...
Nord Pool
Nord Pool AS is a pan-European Electric power, power List of commodities exchanges, exchange. Nord Pool has its main office in Oslo and further offices in Stockholm, Helsinki, Tallinn and London. The company is owned by the European exchange o ...