Utility Week

22 | 17TH - 23RD JANUARY 2020 | UTILITY WEEK Operations & Assets Analysis Frequency response performance 'inadequate' The performance of frequency response pro- viders during August's blackout was "gen- erally inadequate", Ofgem concluded in its final report on the incident released on 3 Jan- uary, "9 August 2019 Power Outage Report". According to the document, there was a 14 per cent shortfall from those required to respond within the first ten seconds and a 17 per cent shortfall from those required to respond within half a minute. Mandatory providers and contracted providers of dynamic primary response per- formed "particularly poorly", with both sets under-delivering by 25 per cent. Ofgem said National Grid Electricity Sys- tem Operator (ESO) had been "unable to demonstrate a robust process for monitoring and validating the performance of individual providers, including mandatory providers". It went on: "It is also unclear how such material under-delivery is accounted for in the ESO's operational planning, how it is addressed on an ongoing basis to ensure delivery of these vital services, and fur- thermore whether this represents value for money for consumers. "We do not believe that better response and reserve delivery would have been suffi- cient to prevent demand from being discon- nected for this event. "However, this is a significant finding given frequency response and reserve are vital balancing services that the ESO must continually procure to secure the system, and expenditure on these accounted for £132 million-worth of balancing service charges in 2018/19." Load-shedding error Furthermore, Ofgem said it had found exam- ples where providers of reserve services were disconnected from the power grid because of the activation of the emergency load-shed- ding mechanism that cut power supplies to more than a million customers across the country. "This is an area which needs address- ing and we would like to see more industry engagement, particularly between the ESO, DNOs [distribution network operators] and generators on the impacts of distributed gen- eration for restoring system stability," said Ofgem. "It is particularly important as the discon- nection of balancing service providers can significantly undermine the recovery of the system frequency." Procurement strategy The report also reiterated concerns over the Security and Quality of Supply Standards and how they are interpreted by the ESO when determining its procurement strategy for frequency response. As required by the standards, the ESO had enough frequency response on hand to cover the largest single potential in-feed loss on the transmission network. At the time, this was a group of three generators near Sal- tend with a combined capacity of 967MW. Even when considering this loss alone, Ofgem said the volume of frequency response held by the ESO le¡ a "narrow margin for error". But the ESO also lacked sufficient reserves to cover the additional Fallout from the blackout Ofgem's '9 August 2019 Power Outage Report' Findings: The investigation found that the combined loss of two large generators, as well as the smaller loss of generation at a local level, together triggered the subsequent discon- nection, loss of power and disruption to more than one million consumers. Two large power stations, Hornsea One (co- owned by Orsted) and Little Barford (oper- ated by RWE) did not remain connected a•er a lightning strike. Remedies: • Hornsea One and RWE agree to pay £4.5 million for not remaining con- nected a•er the lightning strike. • UKPN will also pay out £1.5 million a•er a technical breach of rules. • Ofgem also identified issues surround- ing National Grid Electricity System Operator's (ESO) management of the system. • Ofgem will accelerate its already planned review of ESO's structure and governance. Ofgem has finished its probe into last August's blackout, which left one million consumers off-grid. The immediate hit is £10.5m in fines, but what wider lessons can be learnt? Tom Grimwood reports.

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