On Friday 9 August 2019, over 1 million customers were affected by a major power disruption that occurred across England and Wales and some parts of Scotland. The power outage was due to the loss of a mix of generation including a gas-fired power station and an offshore wind farm.
Though the power disruption itself was relatively short-lived—all customers were restored within 45 minutes—the knock-on impacts to other services were significant. This is especially true for rail services which experienced major delays that extended into Sunday 11 August. The wider disruptions were caused by automatic safety systems under the control of individual service providers, which reacted to frequency and voltage fluctuations, or problems with their back-up power supplies.
Given the severity of the incident, I commissioned the Energy Emergencies Executive Committee (E3C) to conduct a review to identify lessons learnt and put in place a robust action plan to improve the reliability and integrity of our power network. The committee’s final report was published on Friday 3 January. This follows the publication of its interim report on 4 October. The final report sets out 10 clear actions and these will be implemented in full, to help prevent and manage future power disruption events.
Alongside the E3C report, Ofgem also published the conclusions of its own investigations into the incident. This set out a series of cross-industry actions for maintaining the resilience of the electricity system, as well as announcing voluntary payments totalling £10.5 million for companies involved in the power outages.
GB power disruption: E3C lessons learnt and actions
Following a lightning strike on an overhead transmission line, there was a near simultaneous generation loss at two transmission-connection generators; and a significant number of smaller embedded generators connected to the distribution network.
The two transmission-connected generators experienced technical issues near-simultaneously. Both generators have acknowledged the role they played in the incident and since implemented technical fixes to ensure that their systems can withstand similar incidents in the future. The E3C will share the lessons identified with generators across the UK.
The loss of smaller embedded generation on the day was greater than expected. The E3C report sets out a series of actions to assess the need for improvements to the governance, monitoring and enforcement processes for large and smaller generators.
On 9 August, the cumulative loss of generation exceeded the amount of back-up generation on hold. This triggered the first stage, a demand disconnection protection system, which is the last line of defence when the system is out of balance. This resulted in over 1 million customers being disconnected from the network.
Given the events on 9 August, the E3C report recommends a review of how much back-up generation the electricity system operator should be required to hold. As this is funded through consumer bills, the review will include a cost benefit analysis of increasing the amount of reserves.
Although the demand disconnection protection system worked broadly as intended, the review identified some discrepancies in its operation; therefore, the report recommends further analysis of the schemes performance in order to develop options for short and long-term improvements. This includes considering whether distribution network operators should afford particular types of customers any form of protection, especially during the early stages of an incident.
In addition to the direct impacts of customers being disconnected from the electricity network, wider disruptions on the day were caused by the automatic safety systems owned and operated by individual service providers reacting unexpectedly to the frequency and voltage fluctuations on the electricity network; or problems with their own back-up power supplies.
The E3C will consider what more can be done to support essential services owners and operators with advice and guidance to put in place more robust business continuity plans.
Effective communication is a vital part of any emergency response. Unfortunately, industry communications on the day fell below the standard expected, with infrequent and disjointed updates to the general public.
The E3C will develop and roll out new communications processes to ensure the general public receives regular updates during any future disruptions. There will also be a review of operational protocols to make sure they are fit for purpose.
Where appropriate, the E3C and Ofgem reports contain jointly agreed actions and recommendations. The E3C will take the actions set out both reports to drive forward changes across the sector. The committee will provide quarterly updates to my Department and Ofgem.
The UK leads the world by working to eradicate its contribution to climate change by 2050. The actions I have outlined here today will form part of a wider package of work already under way across government and industry to ensure the UK’s energy system remains resilient as we transition to clean and affordable energy.
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