With Ofgem Investigation Officially Closed, We Look Back on the August Power Cut Last Year

The closure of Ofgem’s investigation regarding the 9th of  August 2019 power outage revealed the circumstances that led to the loss of power of over a million customers and provided insights to what energy stakeholders can learn to ensure the resilience of the energy network.


The investigation looked into the compliance of parties involved and whether they fulfilled their corresponding code and licence obligations.  Additionally, the watchdog also published recommendations that will prevent the risk of a similar incidents from happening in the future.


The incident


A power outage on the 9th of  August 2019 caused the interruption of electricity services to more than a million consumers. Consequently, other key services were also disrupted by the operator’s safety systems issues in their existing backup supplies.


Ofgem, in particular, looked in to the serious impact of  the outage to over 500 railway system services that were disrupted because of this incident.


On the day of the power outage, the backup power system held by the Electricity System Operator (ESO) failed to balance the energy system because of  insufficiencies in electricity supply.


The impacts of this was unprecedented and brought the need to investigate the matter and mitigate the risk of a re-occurrence in the future.

Results of the investigation


The Ofgem’s investigation of the August 2019 power outage was officially closed in June 2020 and the regulator found the cause of the incident to be a combination of two failing large generators and localised loss of electricity generation. These events resulted in line disconnection, power loss, and disruption of electricity supply to over a million customers.


RWE-operated Little Barford power station and Orsted co-owned Hornsea Ltd. failed to remain connected to the network after lightning struck their generation areas. Both power stations have made a voluntary payment of £4.5M each to Ofgem’s redress fund for their part in the outage.


The lightning strike was also the reason the national transmission system experienced a routine fault, which was rectified shortly after. It took 45 minutes for the transmission system to be restored throughout the affected areas.


As a response to the unexpected power loss, local network operators disconnected their lines & reconnected customers when services were restored.


The investigation also highlighted that the UK Power Networks reconnected consumers without waiting for a go-signal from the ESO.  This early reconnection of power lines could have jeopardised the system’s recovery but luckily did not have any additional impact on the August power outage.


UK Power Networks admitted to a technical breach when they reconnected their lines before a go signal from the ESO and made immediate internal actions to avoid the re-occurrence of such mistake. The firm also agreed to a £1.5 million payment into Ofgem’s Energy Industry Voluntary Redress Scheme for their error.


All parties involved in the events that led to the power outage gave their full cooperation throughout the industry watchdog’s investigation.

Lessons learned


The loss of power prompted Ofgem to set out strong recommendations to ensure the resilience of the electricity system moving forward.


For system security, the regulator recommends a full review of the standards implemented by the ESO to guard against disruptive events and an enhancement to its approach to testing compliance processes.


Ofgem strongly recommends improving ESO’s transparency on processes related to estimating backup power systems and validating providers’ performance for backup alternatives.


In terms of distributed generation, the industry watchdog recommends a timely review of protection settings for generators as well as the  review of regulatory frameworks and compliance processes.  Ofgem also endorsed the licensing of smaller generators that will require government go-ahead.


Ofgem is pushing for real-time visibility related to distributed generation from the ESO and DNOs to avoid network outages similar to the 9th of August 2019 incident.


Another topic highlighted during the power outage is the existing demand disconnection arrangements, which is something that Ofgem asks to be reviewed for effectiveness. The regulator suggests setting clear requirements for the system and network operators when it comes to customer treatment during power outages.


Ofgem uncovered several issues regarding the ESO’s current procedures and processes for system operation management when dealing with complex conditions. Ofgem shared that the existing systems and core roles of operators should be reviewed to ensure that the legally-binding Net Zero target can be achieved.


Ofgem is working closely with the Department for Business, Energy, and Industrial Strategy (BEIS) ahead of its 2020 position paper on System Governance.






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