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National Grid ESO fails to hit benchmarks as COVID-19 and extreme weather impact August

Day ahead wind forecasts failed to meet expectations, falling outside the target benchmark of 4.41%.

Day ahead wind forecasts failed to meet expectations, falling outside the target benchmark of 4.41%.

Throughout August, almost all of National Grid ESO’s performance indicators showed it falling below expectations.

The operator’s Forward Plan 2020-21 monthly reports show a subset of metrics and performance indicators it uses to track progress on its deliverables, set out in its Forward Plan.

It monitors balancing cost management, energy forecasting accuracy, system access management and month-ahead Balancing Services Use of System (BSUoS) forecasting, all of which fell below National Grid ESO’s expectations of itself in August. Additionally, it monitors security of supply, which exceeded expectations, and right first time connection offers, which met its expectations.

Many of these were driven by the ongoing impact of COVID-19 along with dramatic weather events that throwing various metrics outside of the operators expected limits.

BSUSoS improving but still above the benchmark

For balancing cost management, National Grid ESO set a benchmark of £102 million for the month of August. However, this came in at £114.3 million, more than 10% higher than the benchmark figure and therefore falling below its expectations.

This was largely driven by the stark drop in demand caused by the COVID-19 pandemic and the following lockdown in the UK.

“During the period where demand is impacted by the COVID-19 pandemic, the ESO’s balancing costs spend is expected to be significantly higher than the benchmarks stated here,” the report notes. “During this period, we will continue to report our performance in comparison to the benchmark but will focus on providing a detailed narrative which explains the costs we have incurred.”

It notes that balancing costs for August were lower than they were in July, and closer to the benchmark than they have been since the lockdown was brought in. For example, in April – just shortly after the COVID-19 lockdown was brought in on 23 March – the outrun cost for balancing was £121.4, nearly twice the benchmark cost of £67 million, and in May this grew even starker with the outrun cost sitting at £159 million, while the benchmark was set at just £48.2 million.

The high cost of keeping the grid balanced throughout the lockdown has been well documented, with National Grid ESO identifying an additional £500 million increase in BSUoS costs due to COVID-19 in May.

On the basis of the surging BSUoS costs in June, National Grid ESO increased its forecast for August. Due to less extreme weather and more relaxed lockdown restrictions, there were actually lower constraint costs in August. As such, BSUoS outturned at its lowest level since March, giving an absolute percentage error (APE) of 37%, outside of the 10-20% band set by National Grid ESO for monitoring the month ahead forecast versus outturn monthly BSUoS.

Surging wind and unsteady generation

National Grid ESO’s day ahead demand forecast was not within the benchmark of 447MW, with an average mean error for the month of August of 510MW. It had the most ambitious target for any in the 2020-21 scheme, as the month's performance the previous three years was strong and stable, making demand easy to forecast.

But with COVID-19 impacting holiday plans and changing behaviour, there was more uncertainty. Similarly, the benchmark was not accurate for June or July either.

Day ahead wind forecasts also failed to meet expectations, falling outside the target benchmark of 4.41%. According to August’s report, the monthly mean absolute percentage error for the month was instead 5.55%.

This was largely due to unpredictable weather, with high temperatures – particularly on 10 August in London when it reached 32°C – prompting thunderstorms, with higher than average activity observed for almost half the month. Additionally, Storm Ellen and Storm Francis passed over the UK, impacting the predictability of wind generation.

Despite there being few instances of very high wind across the month, thanks to Storm Francis a new wind generation record was set, with wind output accounting for 59.9% of the generation on 26 August.

There was an increase in the number of delays and stoppages per 1000 outages, rising to 2.88 for the year to date due to three events in August. These were due to additional liaison being required ahead of the scheduled SuperGrid Transformer outage, a delay to a 132kV DNO busbar protection depletion which is under investigation and an outage needed to be re-planned to ensure circuit risk was managed.

Right First Time: Meeting connection expectations

In August, National Grid ESO did meet its expectations for Right First Time connection offers. It saw 26 offers during the month, of which four were subject to re-offer. With one signed in the period, it is hitting its target at 95% Right First Time according to the operator’s monthly report.

Additionally, it pointed to a number of notable developments this year in terms of system insight, planning and network development. In particular, this included the launch of the Network Options Assessment (NOA) and the publication of its FES: Bridging the Gap to Net Zero programme.


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