Furthermore, there may be some restrictions until the Lyse-Fagrafjell power line project in Rogaland is finished in 2023/24. This will occur primarily in connection with maintenance work or faults in the Western Corridor. There may also be restrictions relating to the overall speed at which the flow of power through the lines can be altered.
All interconnectors between Norway and the continent are linked to the power grid in the southwest of the country. This includes the four Skagerrak cables between Norway and Denmark, the NorNed cable between Norway and the Netherlands and the newly installed NordLink cable between Norway and Germany. This latter is currently undergoing final testing and will be available to actors in the power market from December.
Restrictions while power lines are disconnected
While construction is underway, it will occasionally be necessary to disconnect power lines from the system so that they are no longer live. Although power can often be rerouted through other lines, such disconnections will reduce the overall transfer capacity.
According to EVP Systems and Markets at Statnett, Gunnar G. Løvås, the Western Corridor is a comprehensive and necessary upgrade to the power grid in southwest Norway. “The upgrade will be finished as planned next year,” he explains. “In connection with the completion of the various sections, it will be necessary to disconnect individual stretches for a time. This will take place between February and October next year. During this period, there will be additional restrictions on the amount of power that can be transferred via undersea cables between Norway and Denmark, Germany and the Netherlands.”
Even after the new power lines have gone into operation, they will occasionally have to be disconnected for systems maintenance.
The need for the Western Corridor and the Lyse-Fagrafjell power line is well known
The Western Corridor is an important upgrade to the power grid between Kristiansand and Sauda, which will enable electricity to be transmitted at 420 kV along its entire length. The upgrade paves the way for the reliable operation of today’s grid, value creation and the phasing-in of new power production. In addition, the Western Corridor is a precondition for connection to new international interconnectors.
“In order to fully exploit the interconnector cables, it has been necessary to refurbish the power lines between Kristiansand and Sauda. In addition, the Lyse-Fagrafjell power line will act as a backup, thereby playing an important role in the cables’ exploitation,” says Løvås. “This is something we have explained in the reports we have published. We were aware of the need to reinforce the grid, both in Norway and Germany, when we decided to go ahead and build, but still wanted to develop both power lines and interconnectors at the same time, instead of waiting.
More detailed work schedules for the coming years have now been drawn up, and Statnett has performed more specific calculations of the capacity that can be expected next year. Based on a combination of socioeconomic assessments and the physics of the Norwegian power grid, the most expedient solution will be to reduce imports via the Skagerrak interconnectors between Norway and Denmark, while dividing restrictions on exports between the NorNed cable to the Netherlands and the NordLink cable to Germany.
“The restrictions on the Norwegian side will be greatest when power is being imported and exported at the same time on all the interconnectors,” says Løvås. “Situations may arise in which Norway is importing power from Denmark and exporting power to the Netherlands, for example. That would improve the grid situation in southwest Norway.”
Restrictions on the German and Danish sides as well
Restrictions in other countries will also affect capacity on the international interconnectors next year. In Germany, there are also restrictions due to a lack of capacity in the domestic power grid. For 2021, the German authorities have guaranteed a minimum capacity of 11.7 per cent on the grid facilities that are important for NordLink. Statnett’s calculations show that, on average, restrictions on the Norwegian side will result in 65–82 per cent of the capacity being available for export, while over 97 per cent of Norway’s import capacity will be available.
There are restrictions on the interconnectors to Denmark due to faults on an underground cable on the Danish side. This means that there is a difference in export and import capacity, with import capacity to Norway now being lower than export capacity. With current restrictions, Norway’s capacity to import power from Denmark now stands at 953 MW. Given the restrictions on the Norwegian side that will come into effect next year, the average import capacity has been calculated at 583–884 MW.
For both NordLink and the Skagerrak interconnectors, the lowest capacity out of Norway, combined with whatever restrictions there may be on the German and Danish sides will determine actual trading capacity from hour to hour.
Difficult to quickly switch the direction of power through the interconnectors
In addition to the physical restrictions on import and export capacity while the grid is being upgraded, switching from, for example, full import to full export on all interconnectors at the same time is also a challenge for the power system.
“With several new cables in southwest Norway now, we appreciate that it could be difficult to manage such major changes in a short period of time. We are therefore in discussions with the public authorities and other system operators in the Nordic region to find a solution to this issue,” explains Løvås. “In the slightly longer term, the work we are doing in the Nordic region in terms of automation and changing the way we balance the power system will alleviate these problems.”