Major Outage

On 10 January 2020 the Western HVDC Link tripped for the third time in 12 months, taking the 2,250 MW Hunterston-to-Flintshire Bridge bipolar HVDC subsea cable out of service. The outage occurred during a period of strong Scottish wind generation and triggered constraint-action wind curtailment and balancing-mechanism instructions by National Grid ESO to balance the GB system. The repeated faults across the 2019-2020 period drove the regulatory action that immediately followed: on 28 January 2020 Ofgem formally opened an enforcement investigation into NGET and SPT under Special Condition 6I of their Electricity Transmission Licences, examining whether the late delivery and ongoing operational performance of the link constituted licence breaches. Restoration following this fault took several weeks, in line with Wikipedia's characterisation that cable faults on this link typically take several weeks to locate and fix.