NSL interconnector trip causes GB grid frequency dip, batteries respond
Oct 2024Published 15 Sept 2026Responsible editor: Chief Editor
- Where
- NSL interconnector, UK to Norway, 8 October 2024
- What
- Import fell from 1.4 GW to zero, frequency to 49.59 Hz
- Injuries
- None reported
- Response
- 1.5 GW batteries responded, recovery in two minutes
- Cause
- Sudden unexplained loss of 1.4 GW import capacity
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Companies named in the reporting of this entry (being named is not a finding of fault): National Energy System Operator
What happened
On 8 October 2024 at 8:47am local time, the NSL interconnector, which links the UK and Norway, suddenly stopped exporting power, with imports falling from 1.4GW to zero. Grid frequency on the British network fell as low as 49.59Hz within two seconds, breaching the National Energy System Operator's normal operational limits of 49.8 to 50.2Hz. The system recovered within two minutes as fast-acting frequency response services, particularly battery energy storage systems from several operators, injected power into the grid.
Around 1.5GW of batteries across the network responded, including assets optimised by Arenko Group and Kraken, with Kraken-optimised batteries alone delivering over 450MW of response, equivalent to roughly a third of the power lost. No damage, injuries or wider blackout resulted from the event.
Contributing factors
Sudden and unexplained loss of 1.4GW of interconnector import capacity from the NSL Link between the UK and Norway.
Lessons learned
- An interconnector trip can drop 1.4 GW import in seconds and push frequency to 49.59 Hz, so operators must size frequency response to cover full link capacity.
- Battery fleets can inject 1.5 GW within seconds, so contracts should require fast response from aggregated assets across multiple optimisers.
- A single interconnector outage can be covered when response is spread across operators, so systems should avoid reliance on one asset type or site.
More lessons on investigation and fleet-wide checks, spacing, layout and fire spread, from every incident on the register.
Not yet known
- Exact cause of the NSL trip
- Cost of the frequency response services
- Duration of any resulting market price spike
This entry is updated when these are reported. Get an alert for the next one like it.
Published 2026-09-15. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
