Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: The Spanish Grid Drop-out - recently released information.
Date: Sun, 11 May 2025 16:29:30 +1000
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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