The UK’s power sector is seeking an expedited process to any review of system security standards, and pleaded with Ofgem to take seriously concerns over how embedded generation is disconnected during frequency events.
Yesterday National Grid ESO published its final technical report into the 9 August blackout, providing more detail into the root causes of the incident and recommended a number of reviews into both a possible increase in the level of reserve capacity required in the UK and potential amendments to embedded generation disconnection protocols.
Anesco chairman Steve Shine said that while his company welcomed National Grid ESO’s recommendation of reviews of infrastructure, resilience and embedded generation, it stressed that such reviews were “urgently needed” and should be expedited.
“The fact remains that our national grid is vulnerable to power cuts and is getting more vulnerable by the year. Any review must take place quickly and have the full involvement of the wider industry and not be taken as an opportunity to kick the issue into the long grass.
"It is still clear that National Grid were aware that frequency would fall outside of limits, and with more fast response battery storage on the network this power cut could have been prevented. For that reason National Grid should urgently take action to encourage the building of more energy storage to support the UK’s energy security,” he said.
Thom Whiffen, product manager at smart energy tech firm geo, said that homes with connected batteries could have saved the system if they were coupled to a smart demand side response network built upon real-time data and connected systems. Failure to implement such systems could lead such incidents to become a more regular event in the future, he warned.
Richard Black, director at the Energy and Climate Intelligence Unit, said that there was still a lack of clarity surrounding three consecutive trips at RWE’s Little Barford CCGT – clarity which may be forthcoming in subsequent reports into the incident – but also noted the report’s findings on how embedded generation tripped out automatically.
This, the technical report concludes, was as a result of oversensitive sensors which Black said the industry has been aware of for “at least 10 years”.
National Grid ESO’s final report includes in its appendices responses to a number of preliminary questions from the Energy Emergencies Executive Committee (E3C), one of which centred on whether or not relevant lessons from previous incidents – chiefly the 2008 power cut – had been properly limited.
One of those recommendations was that inadequate frequency range settings on embedded generation plant should be modified to improve their resilience to frequency events. Simply put, it was suggested that embedded generators should be allowed to operate as normal during frequency events wherever reasonably practicable.
The ESO’s response to the E3C stresses that changes to Issue 2 of G59 codes included amendments to the settings of frequency protection to distributed generation, and that it was required for these changes to be applied retrospectively for distributed generation in the range of 5 – 50MW, which amounted to around 4GW at the time.
Regular progress reports to the Distribution Code Review Panel showed that this action was implemented, but the remaining volume of distributed generation was deemed “immaterial” given the effort required to make those changes. As a result, the issue does not stand to be corrected until 2022.
Black notes that it would have been Ofgem’s final responsibility, as the industry regulator, for this fault to be allowed to persist.
“It’ll be interesting to see whether MPs or any other body decide to look into the regulator’s apparent lack of interest in the issue,” he said.
National Grid was, however, praised for how it had identified the root cause of the events, and how it had already mooted several possible steps to respond to future needs.
Marc Borrett, CEO at Reactive Technologies, which recently landed a contract with the ESO to start measuring inertia on the electricity system, described the move as a “clear example” of National Grid’s use of new innovations to improve system reliability.
“By working with Reactive to directly measure inertia in order to enhance operational decision-making, National Grid ESO is at the forefront of addressing the kinds of challenges all system operators around the world will face as the necessary transition to renewables continues to transform our grids,” he added.