Flexibility providers were called on by National Grid ESO yesterday (24 February) following an interconnector tripping, causing 1GW to fall off the grid.
Yesterday saw a drop in grid frequency to 49.59Hz at around 1:30pm after the Nemo interconnector with Belgium tripped, causing frequency response providers to jump into action.
National Grid ESO confirmed the trip of the interconnector, which is in its first full month of operation, as well as the drop in frequency to 49.594Hz. However, a spokesperson said the System Operator’s response actions recovered the frequency to normal levels within one minute, with no loss of supply on the system.
Whilst National Grid ESO has a normal operating target of 49.8Hz, the fall in frequency remained in the System Operator’s 49.5-50.5Hz limit, meaning there was no risk of the fault triggering a stress event.
Dr Alastair Martin, founder and chief strategic officer of Flexitricity, confirmed the interconnector had been importing 1GW, which dropped “rapidly to zero”.
Interconnector trips are, however, “relatively common” Martin said, with events like this happening around ten times on a bad year.
Martin added that “teething troubles on a new plant are as common” as reliability issues on older plants.
Flexitricity’s battery customers responded first, moving “rapidly and automatically” into discharge mode as soon as frequency started to fall.
“Shortly afterwards, NGESO instructed us to turn up some combined heat and power generation and turn down some cooling equipment in commercial buildings,” Martin added, with Flexitricity active in the Balancing Mechanism as well as ancillary services, which includes frequency response and short-term operating reserve.
In a post on LinkedIn, Upside Energy’s commercial analyst Charlotte Johnson confirmed that Upside’s monitoring platform delivered a 50MW response comprising 57 scheduled daytime DFFR devices across the UK.
Frequency also fell to 49.59Hz in a frequency event in July, with flexibility providers such as Social Energy and Limejump called on.
Similarly, an interconnector with France tripped in June, an event which also saw 1GW drop off the system and frequency fall to 49.63Hz.