Re: The Spanish Grid Drop-out - recently released information.

On 11/05/2025 4:58 am, john larkin wrote:

On Sun, 11 May 2025 02:46:34 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
 

One of my LinkedIn contacts - an IEEE contact in this case - posted some
new data on LinkedIn, from a "Simon Gallagher, Managing Director at UK
Networks Services | CEng | FIET | FEI | MBA "
>
"We have had an update from ENTSO-E on the Spanish complete power
failure. It is limited, but it helps to build the picture. I have
updated our charts with the new information.
>
Updated timeline:
>
1. Large generators in the South of Spain started to trip at 12:32:57
CET. Over a period of 20 seconds a total of 2.2GW was lost – this is
well beyond largest infeed so not secured against
>
2. The frequency looks to have been contained by system reserves until
what looks like a large trip at 12:33:16
>
3. At this stage, the frequency falls at about 0.5 Hz/s for 4 seconds,
until a rapid collapse starts
>
4. By 12:33:21 the frequency has crashed to 48 Hz. At this stage the AC
interconnectors to France trip
>
5. Low Frequency Disconnect was activated, but looks to have had no
effect because 3 seconds later the system has collapsed completely
>
6. At 12:33:24 the system has completely collapsed, 27 seconds after the
first trip.
>
Some key comments from me:
- LFDD/UFLS seems to have had no impact on the fall of frequency, I
suspect RoCoF relays were operating by this stage, showing how unstable
the grid was
>
- I suspect a lack of rotating mass did mean that there was not enough
time for LFDD to have an impact
>
- A large divergence of frequency opened up between Spain and France for
about 5 seconds. This must have meant a very large phase angle and large
power flows
>
- The previous data that showed the frequency only dropping to 49 Hz
must have been a result of local generators kicking in where the
Gridradar devices were connected to the network (UPDATE this has now
been confirmed by Gridrader, their sensor in Malaga was switched over to
a UPS and then generator at 12:33:20.7, prior to the disconnection of
the Iberian Peninsula and therefore missing some of the frequency drop)"
>
I haven't cut and pasted all of it. This paragraph struck me as interesting.
>
"While I think a lack of inertia had an impact here, that does not mean
that the level of solar and wind was to blame - rather it is how it has
been integrated - more grid forming inverters, more rotating mass is
needed, I suspect."

 Any hints at the precipating cause?

"1. Large generators in the South of Spain started to trip at 12:32:57
CET. Over a period of 20 seconds a total of 2.2GW was lost – this is
well beyond largest infeed so not secured against."
This is a pretty clear statement. It doesn't say anything about why the large generators - type unspecified - lost 2.2GW of generating capacity over a twenty second period, and I haven't seen anything any more specific anywhere.

Maybe some modest local event triggered a fundamentally unstable
system.

Too modest to have been noticed. Power generation systems are quite busy - people are connecting any disconnecting stuff all the time - so it would have taken a rather improbable modest event, or collection of modest events to to trigger this hypothetical mode of instability.
--
Bill Sloman, Sydney