No indications for a cyber attack, rather for a failing security system

Trains came to a halt, just like cars and lifts. Guests in restaurants could no longer order hot food and had to pay with cash. Phones and laptops could no longer be charged. Spain and Portugal were hit by a huge power outage on Monday. The Spanish network operator Red Eléctrica spoke of the largest power outages in the history of the country. In some parts of Spain, the current came back carefully on Monday evening, Tuesday morning the power supply was almost completely recovered. Three questions about this unprecedented power outage.

1How could this happen?

In international media there is plenty of speculation about the cause on Monday. Was it a cyber attack or an exceptionally meteorological phenomenon? Was it a forest fire after which a tree fell on a line? Or was a damage elsewhere in Europe the culprit? The European networks are interconnected. The Spanish Prime Minister Pedro Sánchez said on Monday evening during a press conference that the precise cause was still unknown. An investigation has started, but can take months.

What is now assumed: there was probably a chain reaction, which caused the power outage to affect such a huge area. « I suspect that a malfunction has arisen somewhere, after which the security system failed and parts of the network have eliminated itself one by one, to prevent further damage, » says Martien Visser, lecturer energy transition at Hanze University of Applied Sciences in Groningen. Normally in the event of a local malfunction, only the direct infrastructure is switched off, after which other lines or spare infrastructure take over the power supply.

What caused the chain reaction remains unclear for the time being. The Portuguese network operator pointed out extreme temperature fluctuations as a possible culprit. According to Jean-Paul Harreman, director of market researcher in the field of Energie Montel Analytics, a rare atmospheric phenomenon may have had an influence. « Sudden higher humidity can make cables vibrate on a frequency other than the usual 50 Hertz. If that happens, the security system automatically switches off the cable to prevent damage. » These are called ‘induced atmospheric vibrations’.

But there may also be other causes, such as minor damage to the European network. That happened in the previous major power outage in 2003. Then the whole of Italy was without power after a high -voltage line in Switzerland was eliminated by a fallen tree. In 2021 a malfunction in the Balkans was caused by a sudden increase in power consumption due to the heat and by overheating the systems themselves.

The Spanish network operator calls a sudden, huge dip in the power supply as a cause. That dip would have led to problems in the network connection between Spain and France, after which the electricity grid failed in a large area. Nobody knows what that dip would have caused.

For a cyber attack, for example by Russian hackers, there were no concrete indications or evidence on Monday evening.

2Can this also happen elsewhere in Europe or is the power grid in Spain and Portugal more vulnerable than in the rest of Europe?

In principle, the underlying technology works the same in all EU countries, says Visser. « That is also necessary, because if one country does something crazy, another country can be the victim. »

In general: the more countries are connected, the smaller the risk. Harreman explains: « When your electricity grid is well connected, there is sufficient flexibility in the surrounding countries to absorb problems. You can compare it with a drop of water in a large bathtub – that causes hardly any rimping. » Spain and Portugal are more vulnerable, which he believes is because of their geographical location, on the edge of Europe. « Because of the Pyrenees it is more difficult to create cables, making the connections more limited. In a smaller container, such as the relatively insulated Spain and Portugal, the effect of a malfunction is much greater. If they had been better connected, such as in Central Europe, the risk would have been considerably smaller. »

3What can Spain and Portugal do to start the energy supply?

Step by step, area after area, the electricity came back in different parts of Spain on Monday evening. A spokesperson for TenneT, the manager of the Dutch high -voltage network, lights this so -called Black Start Come on: « Countries have power stations that can generate energy without input from the electricity grid. The Netherlands has four. They are the first to be switched on to generate the first bit of power with which other power stations can be switched on again. »

That procedure goes calmly and controlled, area after area. Harreman says that a too rapid re -in -back can cause large differences between supply and demand, which endangers the stability of the power grid. « If the balance is disturbed, deviations can arise in the standard frequency of 50 Hertz, and you absolutely want to avoid that. » According to the TenneT spokesperson, the system must « be rebuilt little by little, and supply and demand must remain in balance ». That is why the recovery is going so slowly and his technicians were busy all night.

If necessary, other European countries are obliged to provide energy to rebuild the system, according to the TenneT spokesperson. Parts of Spain received power again on Monday, « thanks to France and Morocco, » said Prime Minister Sánchez.

In the meantime, hospitals and data centers receive electricity from emergency aggregates. « But to provide all households in Spain and Portugal with electricity without electricity, you need almost all aggregates in the world, » says the TenneT spokesperson. So the rest awaits in the dark.

This piece was updated on Tuesday morning, April 29, 8.56 am with new information About the power outage.

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