The stand-out event last week was, of course, the grid failure and associated power cuts that occurred on Friday 9 August. This dire turn of events followed the almost simultaneous loss of two large generators, one gas (Little Barford owned by RWE) and one offshore wind (Hornsea 1 owned by Ørsted), at 16.54pm during a very windy period when the system was already calling on replacement generation as several other units withdrew* and as demand hit its evening peak. These incidents in turn caused frequency to fall rapidly across the GB system below the statutory minimum of 49.5Hz, even reaching 48.9Hz.
According to NG ESO, “other generators on the network responded to the loss by increasing their output as expected. However due to the scale of the generation losses this was not sufficient.” The largest in-feed loss (the drop of supply planned for) is currently 1,320MW, smaller than the loss incurred of 1,476MW. It was the biggest shutdown since May 2008 when Longannet and Sizewell B disconnected within minutes of each other, which also triggered local load shedding.
The grid added: “To protect the network and ensure restoration to normal operation could be completed as quickly as possible, a backup protection system was triggered which disconnects selected demand across GB”. About 300,000 UK Power Networks customers were impacted in London and the South East, 500,000 Western Power Distribution customers in the Midlands, South West and Wales, and 110,000 Northern Powergrid customers in Yorkshire and the North East.
After securing the system, DNOs were informed within 15 minutes, so that they could start to restore demand. Given the short duration of the incident, there were no discernible impacts on energy imbalance prices. Indeed, all demand was reconnected within the hour, but widespread transport disruption continued into the weekend.
In a BBC interview on Saturday, the ESO’s Duncan Burt explained that its systems worked well after an “incredibly rare event” of two large power stations disconnecting. Cyber-attacks and unpredictable wind power generation were specifically ruled out as reasons for the failure. “We think that [the ESO’s safety systems] worked well; we think the safety protection systems across the industry, on generators and on the network, worked well to secure and keep the grid safe, to make sure that we preserved power to the vast proportion of the country,” Burt added.
There was a torrent of comment. But noteworthy was Labour Shadow Business and Energy Secretary Rebecca Long-Bailey, who commented: “Disruption on this scale is unacceptable […] Integrating large amounts of renewable energy will require planned and coordinated investments in our networks – which is why Labour has committed to taking the grid back into public hands,” which is a bit of a non-sequiter.
Business Secretary Andrea Leadsom said also on Saturday she would be commissioning the Energy Emergencies Executive Committee to consider the incident. Ofgem also requested “an urgent detailed report from National Grid so we can understand what went wrong and decide what further steps need to be taken. This could include enforcement action.”
These inquiries are likely to focus on a wide range of operational issues. A full blackout was avoided, but the first issue is to understand why the generation was lost. More generally it is inevitable that improvements can be made to procedures and processes to limit the requirement to load- shed and rationalise it where it occurs. Demarcations between NG ESO and DNOs and how they are governed are likely to be considered. But basically these arrangements have been in place for years and pre-date the increasingly decentralised system, and they need revisiting.
Some media reports have touched on “near misses” over recent weeks, including the loss of the French interconnector in early June, with others implying scale deployment of renewables has increased the instability of the electricity system. But NG ESO has been quick to counter these claims. Indeed, it continues to aim to be able to run an entirely low-carbon grid by 2025, which is reflective of its confidence in running the system undergoing rapid transition.
Another key question is whether the amount of frequency response being bought by NG ESO is sufficient for today’s system with mass deployment of distributed energy. How it is using existing flexibility is also likely to be looked at as well as how providers are performing once called. Another issue is likely to be whether it could raise the threshold at which distributed generation disconnects when frequency drops (in industry parlance “Rocof”).
One of the better comments I have seen was from Mark Simon, chief executive of storage developer Eel Power, reported by Platts. “We thought we would be waiting for a cold winter for the impact of intermittent renewables to strike,” he said. “However unwelcome, this is just another milestone in the energy transition from fossil fuels to renewables. It demonstrates with great clarity the urgent need for electricity storage at scale on the UK’s grid.” I agree, and last week’s events will probably bring into closer focus the need to expedite rule changes to enable faster integration of storage batteries across the system.
Elsewhere, there were other noteworthy developments despite the policy lull that marked the start of as the recess. The Committee on Climate Change urged the new BEIS ministerial team to up its response to climate change, following the damage to the Whaley Bridge dam in Derbyshire. Chair of the National Infrastructure Commission Sir John Armitt in some high profile remarks that were widely reported also urged the government to make climate-proofing the UK’s infrastructure a priority. He calls for an additional £43bn of funding, claiming that that the new cabinet’s credibility on climate change “will soon be under the spotlight”.
On the regulatory front Ofgem also announced that the default price cap will fall £75 from £1,254/year to £1,179/year from for the coming winter (October-March). The pre-payment meter cap will fall from £1,242/year to £1,217/year for the same period.
Meanwhile I am continuing to push forward with both P379 and Smarter Norwich. Both are requiring a lot of engagement but they continue to head in the right direction, and I will say more in my next update. And even though it’s too early to get excited, Blackpool pulled off a comfortable 3-1 win at Southend on Saturday.
And as I post this, I note I have just hit 500 followers on Twitter. If you don’t follow, please do. Its @newangliaenergy.
* These came during 4.00-7.00pm (periods 33-38) from Enfield Energy Centre (CCGT, -416MW), Little Barford Unit 1 (CCGT, -400MW), Damhead Creek (CCGT, -100MW), Rye House 1 (CCGT, -95MW), Connah’s Quay (CCGT, -86MW), Hornsea One (Offshore wind, -800MW), Drax 4 (Biomass, -85MW), Lynemouth 1 (Biomass, -17MW), Drax 3 (Biomass, – 15MW), Aberthaw auxiliary unit 8 (OCGT, -19MW).