UK electricity operator National Grid has said the network’s security standards need reviewing following the August power cut which plunged 1m Britons into darkness.
In National Grid’s report into the outage, published today by energy watchdog Ofgem, it concluded that a simultaneous loss of power at two power stations “represented an event beyond the standards to which the system is normally secured”.
Ofgem said that the government is carrying out its own separate investigation into the power cut which affected 1m people on 9 August.
Thousands were stranded after trains were delayed and cancelled, leaving commuters unable to get home from work. The disruption carried on into Saturday.
National Grid’s report said: “Two almost simultaneous unexpected power losses at Hornsea [Yorkshire] and Little Barford [Bedfordshire] occurred independently of one another but each coincident with a lightning strike.”
Generation would not normally “be expected to trip off or de-load in response to a lightning strike,” it said. “This represents an extremely rare and unexpected event.”
The energy network operator said the “automatic protection systems… worked in line with their design to protect as much electricity demand as possible”. Yet it said this was not enough to prevent disruption to the grid.
“The disruption to rail services extended through Friday evening and into Saturday morning due to the fact that approximately 30 trains stopped operating and could not be restarted following the original frequency drop.”
National Grid recommended a review to security standards “to determine whether it would be appropriate to provide for higher levels of resilience in the electricity system”.
It also recommended that “communication processes and protocols, in particular during the first hour, should be reviewed to support timely and effective communication in any future event”.
“The settings on the internal protection systems on electric trains should be reviewed to ensure they can continue to operate through ‘normal’ disturbances on the electricity system,” it added.
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