Inspection Survey

From 25 May to 28 July 2020, Energinet and the cable supplier Prysmian carried out a forensic sampling campaign on the Skagerrak 4 (SK4) Danish onshore HVDC cable to investigate the root cause of three serious faults that had occurred during 2019 (6 February, 21 July and 9 October — all on the Danish onshore section of SK4). At several points along the route the cable was excavated, cut through and pieces extracted for analysis by Energinet, by Prysmian, and by an independent third-party expert firm. The SK4 interconnector was fully out of service throughout the sampling window. The Director of Energinet Eltransmission, Henrik Riis, stated at the time of the announcement that Energinet and the cable supplier had agreed to perform a thorough analysis and obtain expert assessments before deciding what further measures would be needed, emphasising that SK4 had to return to service at full capacity to support trade, export and import between Denmark and Norway. The article reports that since October 2019 total Skagerrak system capacity had been reduced from 1,700 MW to 1,387 MW in the primary direction and 950 MW in the secondary direction, with a new IT solution expected to lift the secondary direction to 1,350 MW.