UK blackout report
Image credit: Shannon Tremaine on Unsplash

The much-awaited final report from the UK’s National Grid ESO on the blackout that affected one million people on August 9th 2019, has revealed that Britain’s transmission systems protection measures operated “in line with the design and in compliance with the Grid Code requirements on fault clearance”.

The investigation which was ordered by the UK’s new energy minister Andrea Leadsom, energy regulator Ofgem, and Britain’s Department for Business, Energy and Industrial Strategy (BEIS), relied on input and analysis from organisations such as Orsted, RWE, NGET, and Govia Thameslink Railway, some of which were suspected of having played a contributing role in the event, which saw commuters stranded across much of the UK’s public transport system, with road-users stuck in peak-hour Friday afternoon traffic.

The blackout was ultimately blamed on a lightning strike, in-line with initial findings, which in turn resulted in the shutdown of the UK’s largest wind farm, Hornsea One, and the secondary, almost simultaneous tripping of a steam turbine at the gas-fired Little Barford power plant, run by RWE.

National Grid ESO has suggested that security standards be reviewed to establish whether higher levels of resilience in the system are required, and stressed that communication processes and protocols should also be reviewed to ensure timeous, effective communication in the event of future blackouts.

The report further recommends that facilities connected to Britain’s low-frequency demand delivery system be reviewed “to ensure no critical infrastructure or services are inadvertently placed at undue risk of disconnection”.

It further suggests that the protection systems employed on electric trains be reviewed to ensure undisrupted operation during any future disturbances to the power grid.

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-UK’s National Grid responds after blackout
-UK Energy Emergencies Committee, Minister Leadsom start investigation
-UK’s Ofgem to investigate Ørsted, RWE, and DNO’s role in blackout
Lightning strike caused UK blackout – initial report

The report’s findings also question the potential benefit of establishing standards related to grid events which resilience and protection systems for critical infrastructure and services should be based.

The grid operator has suggested that the delivery timeline for the UK’s Accelerated Loss of Mains Change Programme should also be reassessed, so as to reduce the risk of inadvertently tripping and disconnecting embedded generation.

According to National Grid ESO, the incident has provided valuable learnings, and these will

Ofgem has announced: “The technical report will form evidence as part of Ofgem’s formal investigation into the power cuts and the actions of National Grid ESO, National Grid Electricity Transmission, 12 distribution network operators in England and Wales and the generators RWE Generation (owner of Little Barford Power station) and Orsted (owner of Hornsea offshore wind farm).

“Ofgem launched the formal investigation on 20 August after receiving National Grid Electricity System Operator’s initial report.

“The government is separately reviewing the actions of National Grid Electricity System Operator. Its Energy Emergencies Executive Committee plans to provide a report on initial findings in the coming weeks to the Secretary of State for Business, Energy and Industrial Strategy by the end of this month.”