Orsted faces an investigation into whether it broke its licence conditions over the role of the Hornsea 1 offshore wind farm – the world’s largest – in a massive UK power outage.
UK energy regulator Ofgem will investigate potential licence breaches by the offshore wind developer and a raft of other parties over the outage, which affected more than a million people and caused transport chaos on 9 August.
Others in the spotlight include network operator National Grid, twelve distribution network operators and RWE – the operator of the Little Barford gas-fired plant that was the other major generation source involved in the outage.
Ofgem has the power to fine companies up to 10% of their UK turnover for breaches of the Electricity Act.
The regulator announced the probe as it published an initial report by National Grid into the events of 9 August.
That confirmed earlier media reports that a lightning strike on a transmission circuit was the spark for the outage, with both Hornsea 1 and Little Barford removing a total of 1.4GW from the grid “within seconds of each other”.
“This unexpected loss of generation meant that the frequency fell very quickly and went outside the normal range of 50.5Hz – 49.5Hz,” said the National Grid report, ordered by Ofgem immediately after the outage.
Despite having 1GW of backup power held to cover generation loss, the scale of the 9 August caused systems to kick in to safeguard the network against frequency loss, disconnecting about 5% of UK demand.
Orsted has not yet commented on Ofgem’s inquiry but said last week: “During a rare and unusual set of circumstances affecting the grid, Hornsea One experienced a technical fault which meant the power station rapidly de-loaded – that is, it stopped producing electricity.
“Normally the grid would be able to cope with a loss of this volume (800MW). If National Grid had any concerns about the operation of Hornsea 1 we would not be allowed to generate. The relevant part of the system has been reconfigured and we are fully confident should this extremely rare situation arise again, Hornsea 1 would respond as required.”
Hornsea 1 will be the world’s largest offshore wind farm at 1.2GW when it enters full service.