Meredith Angwin @MeredithAngwin
·
Dec 23
Grid frequency drifting outside operational limits implies the system is running at the margins. https://watt-logic.com/2024/12/23/gb-grid-frequency/
Thanks to Kathryn Porter for this analysis!
From watt-logic.com

chrispydog @chrispydog
When I explain this stuff to people: "Have you seen when a spinning top starts to wobble, and what comes next?"

Most people 'get it' pretty fast.
4:34 PM · Dec 24, 2024. //

I then analysed the number of 15-second intervals in each winter season for which the operation or statutory limits were breached. The results are in the table below. As can be seen, in the past 4 years, there have been c 500 times the upper operational limit was breached, but in 2017 – 2019 the number was higher. The lower limit has tended to be breached less often – 2022 was an outlier with a very high number of breaches. There has also been a consistent trend of lower limit breaches increasing in frequency, which is consistent with falling grid inertia (see chart). //

This fits with the expected picture that the grid is becoming less reliable. It is also interesting that when individual occurrences are inspected, it is more often the case that frequency has drifted outside the operational range rather than suddenly falling out as would be expected from an outage. This is more worrying as it points to a general difficulty in maintaining stable frequency – things will always break and trip, and the grid is designed to deal with that, but these drifts outside the range speak more to a wider reduction in stability versus what is expected.