Power Cut in Spain and Portugal - "Rare Atmospheric Phenomenon"

Mick West

Mick West

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There seems to be a lot of uncertainty and speculation as to the cause of the peninsula-wide power cuts in Spain and Portugal:

Article:
Portugal's grid operator, RNA, gave a rather complicated explanation for Monday's massive power outage which left much of the Iberian Peninsula without power.

It blamed a rare atmospheric phenomenon which caused "oscillations" and "vibrations" in the high power lines, which in turn resulted in "synchronisation failures".

REN said: "Due to extreme temperature variations in the interior of Spain, there were anomalous oscillations in the very high voltage lines (400 kV), a phenomenon known as 'induced atmospheric vibration'. These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network."


but
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Article:
The weather in Spain on Monday was calm and sunny with average spring temperatures.

According to an expert [the ITV reporter] spoke to, it would be "really really weird" for this weather to have caused - or 'induced atmospheric vibrations'.


But also:

Article:
A fire, reported to be in Southern France between Perpignan and eastern Narbonne, which damaged a extra-high-voltage power line, has also been identified as a possible cause by REN.[21] France's Réseau de Transport d'Électricité (RTE), the nationwide transmission system operator in charge of maintaining said power line, declared on its official X account that there were no fires in the area.[22]

The Spanish cybersecurity agency Incibe was reported to be investigating the possibility that a cyberattack caused the incident.[23][24]


With the continued uncertainty, there are lots of conspiracy theories and other theories out there.
 
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I wonder whether the text in the REN quote is poorly translated.

"Oscillations" could easily be a translation for "frequency", with makes a bit more sense in this situation. Grid frequency violations can cause synchronization problems for power suppliers and the grid as a whole.

That might also explain the weather reference to the extent that sudden cloud cover or rapid changes in wind speed introduce potential frequency instability. The weather report doesn't seem to support this theory, though.
 
What is the latest official news on why it happened? The news outlets over here seem to have forgotten all about it already.
 
It will probably take a few days or weeks for them to assess what actually caused this. I'm an electrical engineer that doesn't work in the field, but my uni colleagues who do have never heard of 'induced atmospheric vibrations' as a cause for grid malfunction.

What everyone seems to agree is that the high dependency on renewables makes it hard to regulate (as in, control voltages, frequencies and power flow) and now makes it hard to restart the grid.
 
NorCal Dave said:
Is that a big bump in solar right before it appears the nukes and natural gas goes offline?
Click to expand...
They call it sunrise. It's happened pretty much the same in the 2 weeks before, as the same site readily reveals. If the cause was that simple, they'd know already.

The graph shows that photovoltaics provided half of the power available after the drop, and wind power was barely affected at all.
 
Gaspa said:
What everyone seems to agree is that the high dependency on renewables makes it hard to regulate (as in, control voltages, frequencies and power flow) and now makes it hard to restart the grid.
Click to expand...
If you had a source for that claim, that'd be great.
 
Mick West said:
Portugal's grid operator, RNA, gave a rather complicated explanation for Monday's massive power outage which left much of the Iberian Peninsula without power.

It blamed a rare atmospheric phenomenon which caused "oscillations" and "vibrations" in the high power lines, which in turn resulted in "synchronisation failures".

REN said: "Due to extreme temperature variations in the interior of Spain, there were anomalous oscillations in the very high voltage lines (400 kV), a phenomenon known as 'induced atmospheric vibration'. These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network."
Click to expand...

I'm seeing news sources saying that this was mistakenly attributed by Reuters to REN, and it was picked up by other news outlets.

External Quote:

3. Was the blackout caused by a 'rare atmospheric event'?
Portuguese grid operator REN denied initial reports attributed to the agency on Monday, which stated that the blackout was caused by a rare atmospheric event.

Portuguese original:
3. O apagão foi causado por um 'raro evento atmosférico'?

O operador do sistema português REN desmentiu relatos iniciais atribuídos à agência na segunda-feira, dando conta que o blecaute teria sido causado por um raro evento atmosférico.

source: g1 - one of the largest brazilian news site
External Quote:

G1 made a mistake when it reported on Monday (28) that the blackout in Spain and Portugal had been caused by a rare atmospheric phenomenon. The information was based on a report by the Reuters news agency attributed to the Portuguese operator REN. The agency later corrected the information, clarifying that REN had not issued this statement. The correction was made at 3:32 p.m. on April 28

Portuguese original:
O g1 errou em informar nesta segunda-feira (28) que o apagão na Espanha e em Portugal havia sido causado por um fenômeno atmosférico raro. A informação se baseou em relato da agência Reuters atribuído à operadora REN, de Portugal. A agência corrigiu posteriormente a informação, esclarecendo que REN não havia emitido essa declaração. A correção ocorreu às 15h32 de 28 de abril.

source: errata from g1
I haven't found Reuters's correction so far.
 
From the Spanish Meteorology Agency (AEMET) :

External Quote:

During April 28th, no unusual atmospheric or meteorological phenomena, nor sudden temperature changes were detected in our network of meteorological stations

Source: https://x.com/AEMET_Esp/status/1917129786985533885?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1917129786985533885%7Ctwgr%5E777854f462899dac1f14d56c15ed7c500d1dae1f%7Ctwcon%5Es1_c10&ref_url=https%3A%2F%2Fefe.com%2Fespana%2F2025-04-29%2Faemet-apagon-no-hubo-fenomenos-meterologicos-inusuales%2F
 
Article:
The Spanish government said on Sunday that it would need 'several more days' to determine the cause of the nationwide power outage on 28 April, which also extended into Portugal and parts of southwestern France.

In an interview with Spain's El País, the country's Minister of Ecological Transition and third deputy prime minister, Sara Aagesen (main image), said that 'all hypotheses' were still under consideration, including the possibility of a cyberattack. Aagesen was previously Spain's Secretary of State for Energy.

One theory being examined involves solar panel installations in southeastern Spain potentially destabilising the electrical grid – an explanation that grid operator Red Eléctrica has already proposed.

'We know that those installations stopped working in the system,' Aagesen confirmed.

However, she cautioned against drawing conclusions too soon: 'Talking about solar panels (as the cause) might be hasty,' adding that blaming renewable energy for the incident was 'irresponsible and simplistic'.
 
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Very little is known about the cause of the black out. So far, there was a first anomaly in the southwest of Spain, compatible with the loss of generation, but the grid was able to recover from it. A second event just a few seconds later happened, that led to the instability of the grid, caused the loss of interconnection with France, isolating the penninsula, and finally the whole grid collapsed.

Source:

Source: https://www.youtube.com/live/dSIWH4DWTHU?si=7ytTVrt1WNVWoSDp&t=161



What caused the anomalies in the southwest region of Spain in the first place is still unknown. Rumors say that the generation loss was from some photovoltaic plants, but I haven't seen any confirmation yet.
Gaspa said:
What everyone seems to agree is that the high dependency on renewables makes it hard to regulate (as in, control voltages, frequencies and power flow) and now makes it hard to restart the grid.
Click to expand...
This is what I have been reading about in different forums.
 
jplaza said:
What caused the anomalies in the southwest region of Spain in the first place is still unknown. Rumors say that the generation loss was from some photovoltaic plants, but I haven't seen any confirmation yet.
Click to expand...
And the second question is, why was a regional anomaly able to collapse the national grid? This points to lessons that need to be learned in power grid design. (Especially as it was likely signals from the grid that caused those PV generators to disconnect.)

Perhaps this is the future:
Article:
South Australia's 150 MW / 193.5 Hornsdale Power Reserve, more commonly known as the Tesla Big Battery, will now provide inertia services to Australia's National Electricity Market after securing approval from the Australian Energy Market Operator. Neoen says it is the first big battery in the world to deliver the service at such a scale.

JULY 27, 2022

After two years of extensive trials, Neoen's Hornsdale Power Reserve now has the capacity to provide an estimated 2,000 megawatt seconds (MWs) of equivalent inertia to South Australia's grid through Tesla's Virtual Machine Mode technology.

Known as virtual synchronous machines or grid forming inverters, this technology gives batteries the capacity to help stabilize the grid by providing inertia. Along with frequency control services, inertia is necessary for operating a stable grid and is especially important after major disturbances. Until now, inertia services have only been provided by gas or coal-fired generators and their rapid retirement is causing inertia shortfalls or grid instability – especially in regions like South Australia, where renewable penetration has reached 64% over the last 12 months.
 
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Gaspa said:
What everyone seems to agree is that the high dependency on renewables makes it hard to regulate (as in, control voltages, frequencies and power flow) and now makes it hard to restart the grid.
Click to expand...
Well, nuclear, oil and coal are also hard to restart, so...

I believe the majority of PV and wind systems are able to start without external power, as the equipment that needs to be powered for that is rather minimal, so a small reserve battery does the job. There's no need to light a fire or pump water.

I found that you can buy smaller grid battery systems (10 MW seems to be a common size) "off the shelf", and I found several news reports of German cities having them installed.
 
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Mendel said:
I believe the majority of PV and wind systems are able to start without external power, as the equipment that needs to be powered for that is rather minimal, so a small reserve battery does the job.
Click to expand...
Solar does not need any battery at all, it draws all the power it needs from the PV panels (if the sun is up). Indeed grid-connected solar inverters installed at home have a function which is called 'anti-islanding' and blocks the inverter if the power goes off from the main grid. It may seem silly the solar inverter turns off just when power would be more needed, but it's a basic safety function to avoid worse problems (including electrocuting people working on the grid wires) and is mandated by regulations. I'm not sure about big PV generation plants, my direct experience is limited to inverters up to a few kW, but reconnecting a single inverter to the grid once it comes back takes seconds at most.

I'm also not sure about wind farms, but every other power generating system requires external energy to start (even hydro: valves are operated electrically and the generators themselves need power for the excitation windings).


Electric grids are very complex things and the risk of a cascading failure which brings down the whole system is, unfortunately, always present:

External Quote:

Cascading failure caused the following power outages:

Click to expand...
Solar and wind power generation (variable energy clusters) present particular challenges to the management of a grid, which can be counteracted with energy storage, a grid structure better suited to distributed power generation and better grid management technologies, but on the flip side distributed generation (as opposed to big power stations) allows for more resilience because a fault will only affect a small part of the generating capacity.

I would wait the enquiry to be over and the report released before trying to derive any lessons (or point any finger) from this blackout. Surely I commend the actions of the technicians in charge of the Spanish grid because restoring power after a whole grid failure (a "black start") is no easy task and I was surprised it took them so little time.
 
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Mauro said:
I'm also not sure about wind farms, but every other power generating system requires external energy to start (even hydro: valves are operated electrically and the generators themselves need power for the excitation windings).
Click to expand...
I think on hydro, they might be able to open valves manually? But at any rate, it takes a lot less energy than getting pumps etc. going.

Wind turbines adjust their blades to not generate "lift" when they power off, and I expect they also brake the rotor, and all that needs to be undone. The big turbines also need cooling. The big off-shore wind parks can black start, taking power from diesel generators. Smaller installations typically wouldn't (and shouldn't, for the safety reason you outlined).
 
Mendel said:
I think on hydro, they might be able to open valves manually?
Click to expand...
Maybe yes, in a small plant, but one needs anyway electricity to power the excitation windings of the alternator (unless one has an alternator with permanent magnets, but they are not suited to power plants for what I know, at least they are quite uncommon).

Mendel said:
But at any rate, it takes a lot less energy than getting pumps etc. going.
Click to expand...
That's sure! Indeed hydropower stations are often used as black-start sources because they use little self-power and are quick to start, while a power station with steam turbines requires more energy to operate and more time to bring up the steam pressure (but gas-fired plants are rather good as black start sources too, while big thermal or nuclear plants are the worst in this respect). Solar plants are not earmarked as black start sources because they cannot be relied upon at night or in bad weather conditions, but on a sunny day they would have no problems in starting up an island (then, connecting the rest of the grid to an island sustained by solar may not be the easiest of the tasks, and a thunderstorm could ruin the day).
 
Mendel said:
And the second question is, why was a regional anomaly able to collapse the national grid? This points to lessons that need to be learned in power grid design. (Especially as it was likely signals from the grid that caused those PV generators to disconnect.)
Click to expand...
Some years ago (2003) there was a massive power outage in the eastern United States and Canada that lasted up to two days in places. They finally determined the initial cause to be at a substation very near to me in Ohio. A power line, one that was unsupported for a stretch where it crossed a ravine, sagged in the summer heat and shorted out when it hit a tree. I know the line, I know the ravine, and I think I even knew which tree. The nearest home had every electrical appliance destroyed. Yet we, five miles away, lost power only for a couple of two-second bursts, while distant places like New York City and most of Ontario were blacked out completely for an extended period.

The cause was a "cascade", which, in my limited understanding occurs when one part of the power grid demands power from another (a regular occurrence), which then gets it from another, etc. But errors (both human and computer) in that redistribution caused the problem. We had the "regional anomaly" right here, while far-off places suffered the consequences.

External Quote:

The outage, which was much more widespread than the Northeast blackout of 1965, affected an estimated 55 million people, including 10 million people in southern and central Ontario and 45 million people in eight U.S. states.

The blackout's proximate cause was a software bug in the alarm system at the control room of FirstEnergy, which rendered operators unaware of the need to redistribute load after overloaded transmission lines drooped into foliage. What should have been a manageable local blackout cascaded into the collapse of much of the Northeast regional electricity distribution system.
......
According to the official analysis of the blackout prepared by the US and Canadian governments, more than 508 generating units at 265 power plants shut down during the outage.
https://en.wikipedia.org/wiki/Northeast_blackout_of_2003
(This article also contains a lot of the technical details behind the outage.)

In contrast, a couple of years ago there was a much-publicized outage in Texas, the "Ted Cruz flees to Cancun" one. The main part of Texas was on a stand-alone system, and I understand a very expensive but poorly maintained one. They bragged about being independent of a larger distributive grid, but the result of that was that when they were knocked out, there was no power flow from elsewhere to help them.

Grid or no grid? It's sort of a damned if you do, damned if you don't situation, but anecdotally, the grid seems to have saved more outages than it caused.
 
Ann K said:
The cause was a "cascade", which, in my limited understanding occurs when one part of the power grid demands power from another (a regular occurrence), which then gets it from another, etc. But errors (both human and computer) in that redistribution caused the problem. We had the "regional anomaly" right here, while far-off places suffered the consequences.
Click to expand...
Yes. And the cause wasn't the anomaly, it was the failure of the grid to adjust properly.
Article:
The report states that a generating plant in Eastlake, Ohio, a suburb northeast of Cleveland, went offline amid high electrical demand, putting a strain on high-voltage power lines (located in Walton Hills, Ohio, a southeast suburb of Cleveland) which later went out of service when they came in contact with "overgrown trees". This trip caused load to transfer to other transmission lines, which were not able to bear the load, tripping their breakers. Once these multiple trips occurred, a number of generators suddenly lost parts of their loads, so they accelerated out of phase with the grid at different rates, and tripped out to prevent damage. The cascading effect that resulted ultimately forced the shutdown of at least 265 power plants.
Remember, this was before renewable, and they still had frequency problems.
External Quote:
During the first two hours of the event, various officials offered speculative explanations as to its root cause:
Sounds very familiar to what happened now. Even the technical statement 4 days later missed the mark. It took 5 months for the interim report to be released.
 
Mendel said:
And the cause wasn't the anomaly, it was the failure of the grid to adjust properly.
Click to expand...
One factor which I had not realized until I looked up this article was that it wasn't just the high heat of the day which caused the Walton Hills line to sag into the trees, but also the heat generated by high power usage on that line due to the Eastlake facility being shut down.

The use of air conditioning and its high power demand is something that never seems to be considered by those who hand-wave away a warming climate. It's been said of cities like Phoenix that they would be nearly uninhabitable without air conditioning, and their prolonged periods of over-100 degrees would seem to support that. When my husband's grandmother ran away from home in Minnesota as a teenager and ended up in Phoenix at about the time it became a state, she worked as a housekeeper for a wealthy family ...and those with the means to do it in those pre-air conditioning days vacated Phoenix in the summer, heading up to the cooler mountain climate near Flagstaff.

The recent power outage in summer heat in Texas, as well as the heat wave in largely un-air conditioned Europe, were responsible for a good many deaths.
 
Ann K said:
The use of air conditioning and its high power demand is something that never seems to be considered by those who hand-wave away a warming climate..
Click to expand...
Yeah, and it's huge, because there're very few ways of doing it without electricity; mere heating can be achieved by burning barney:

External Quote:
The three largest categories and their shares of residential site electricity consumption in 2020 were:2
air conditioning 19%
space heating 12%
water heating 12%

Lighting and refrigerators are used in nearly every home, and they are the next two largest electricity end uses. The shares of annual electricity end uses can change from year to year based on the weather.
https://www.eia.gov/energyexplained/use-of-energy/electricity-use-in-homes.php

Raw data for those who want to dig deeper: "2020 RECS Survey Data: Table CE4.1 Annual household site end-use consumption by fuel in the United States—totals, 2020" https://www.eia.gov/consumption/residential/data/2020/c&e/pdf/ce4.1.pdf
 
As mentioned above the grid forming capacity of batteries is there, but I don't think it is widespread yet among every installation. When it is available it can be very quick, but that quickness might also be a hard thing to control if there are a lot of different ones all trying to act at the same time. They'll likely have to come up with some kind of priority and control system to prevent strange feedback loops.
 
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