On 12 May, travel on the London Underground was disrupted by a ‘short power cut’ in south-west London caused by a transmission network fault.
Tube lines were suspended or delayed and the fault in the transmission network is also cited as the cause of a fire at an electricity substation at Aberdeen Place in Maida Vale, in west London. The London Fire Brigade said that three metres of high-voltage cabling connected to the substation was “completely destroyed by fire”.
The substation was the site of another fire just a fortnight before (29 April) when a transformer was set alight. At the time, UK Power Networks, which operates the low-voltage distribution network across London, said faulty equipment in the substation caused the blaze but power supply to the area was not interrupted.
Following the news of travel disruption, Current± reached out to both National Grid, the transmission system owner for Great Britain, and UKPN.
National Grid apologised for “any inconvenience”, stating that there was a fault on its transmission network in central London on Monday afternoon.
A spokesperson added: “The fault was resolved within seconds and did not interrupt supply from our network, but a consequent voltage dip may have briefly affected power supplies on the low voltage distribution network in the area.”
The low voltage network is owned and operated by UKPN, however the company told Current± that the events on 12 May were not a UKPN incident.
UKPN released a statement on the day of the fault, stating: “A fault on National Grid’s equipment briefly interrupted power across parts of London, shortly after 2pm today (12 May).
“Our supply to customers, including Transport for London (TfL), was restored in less than a minute and we have offered assistance to TfL should they require it.”
What causes a power cut?
The operational limit for the electricity grid is between 49.8Hz and 50.2Hz. A dip or surge in the frequency on the network is one cause of power outages alongside unplanned issues, including extreme weather events.
The National Energy System Operator (NESO) has several tools in its control room to prevent significant power supply issues. In October last year, following two interconnector trips, battery energy storage systems (BESS) stepped in to inject power onto the grid during the disruption.
More recently, having forecasted a system margin shortfall of 1,700MW and a contingency requirement of 900MW, NESO issued an Electricity Margin Notice (EMN), signalling it would need the market to be ready to provide additional capacity.
Under usual circumstances, an automated Capacity Market Notice (CMN) is issued when there is a forecasted generation shortfall. An EMN is a stronger signal to the market, reflecting an increased concern from NESO.
