The UK’s National Grid has published a report into the power outages that affected Britain on 9 August, causing widespread disruption at rush hour, particularly into and out of London. The outage lasted for an hour, and caused a loss of electricity to 1.1 million customers.
The report stated that a lightning strike and unexpected generation losses resulted in more than 1 GW of supply going offline, resulting in a large drop in the power frequency in the grid, taking it outside operating limits.
National Grid said that the regulator Ofgem should review “whether it would be appropriate to provide for higher levels of resilience in the electricity system,” as the scale of power generation loss exceeded normal protection standards.
National Grid said a lightning strike hit the transmission system late afternoon on 9 August, resulting in the tripping of 150 MW of generation. As the same time, the unexpected loss of power from Hornsea offshore wind farm and Little Barford gas-fired power station resulted in more than 1 GW going offline, and a large drop in frequency. The frequency drop resulted in a further trip of 350 MW, and then a gas turbine at Little Barton tripped, bringing the total loss of generation to 1.7 GW. The 1 GW of emergency back-up power held in reserve proved insufficient. National Grid has said that Ofgem needs to carry out a review of how much emergency back-up power should be held in reserve.