Spanish grid operators ruled out cyberattacks on Monday as the cause of a massive blackout that crippled parts of Spain, Portugal and France.
Red Ereclica manager Eduardo Prieto said the preliminary findings had “no interference in the control system” to suggest an attack, and repeated Portuguese Prime Minister Luis Montenegro the day before.
However, the exact reason behind the cut is still unknown.
The grid operator said Tuesday that he “cannot introduce a conclusion” until he has obtained specific data. Spanish Prime Minister Pedro Sanchez said investigators were trying to determine the cause and would take all necessary steps “to ensure this doesn’t happen again.”
Information flows about what happened during the cut, leading to theories about what caused it. Experts told the BBC it is likely caused by several disorders.
This is what we know and what questions remain unanswered.
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Sánchez said Monday evening that 15GW of electricity — equivalent to 60% of the demand at the time — was “suddenly lost from the system in just five seconds.”
Prieto said at a press conference Tuesday that the two “cutting events” were barely separated from Spain southwest.
One of the issues that Spanish grid operators may have mentioned was when the utility company identified inconsistencies in supply and demand for electricity that could lead to instability and temporarily disconnected to protect the system.
However, Sanchez later said the blackout was “not an issue of excessive renewable energy.” He said there were no failures in compensation (meaning supply) and there was relatively low demand for very ordinary electricity in the days leading up to the crisis.
So, what exactly happened? Outages at this scale, not just renewable energy, but on average, occur once a year somewhere in the world, at one point in time, especially since many systems fail to power frequently.
The discrepancy between electricity demand and or demand could change the frequency of electricity grids that are 50Hz in Europe and the UK.
If the frequency changes from a narrow range, the equipment can be damaged.
“When a large company detects that frequency is moving out of acceptable range, it can protect the equipment offline,” said Professor Hannah Christensen of Oxford.
She added that if many companies do it quickly and in succession, it could have a “cascade effect” and lead to power outages.
But when it comes to renewable energy, operators have very accurate short-term weather forecasts, so they adjust the power source accordingly to predict that there will be a surplus of solar power, Professor Christensen said.
Renewable electricity poses a different challenge to fossil fuel energy.
“It’s a bit confusing that this wasn’t predicted,” she said.
Professor Keith Bell of Strathclyde University added, “If a system depends on the sun and the wind, we will design a system that reflects it.”
“Spain has a lot of experience with wind and solar, and has a long-standing system of predicting the weather and its impact,” he said.
“All kinds of systems fail,” he added. “Whether it’s due to renewable energy, fossil fuels, or nuclear power, things won’t go well. This could be a Swiss cheese model with holes in the system that happen to line up.”
Red Ereclika also suggested that the drop in power caused grid interconnections between Spain and France.
Two basic technologies are used to interconnect grids or parts of the country. This is a standard transmission line that carries alternating currents and a standard transmission line that carries increasingly high voltage direct current lines.
Spain has a high voltage line that served seven years ago. So, Professor Bell said it’s well tested.
The Iberian Peninsula is often referred to as the “electric island.” This means that they are vulnerable to obstacles as they rely on only a few links to France through the Pyrenees.
Sánchez said that electricity was returned online thanks to its connections with France and Morocco, as well as gas and hydropowered power sources.
Portuguese grid operator Ren Ren rebutted the initial report attributed to the agency on Monday.
The Portuguese message “due to extreme temperature fluctuations in internal or in Spain, there was an abnormal vibration in a very high voltage line (400 kV), a phenomenon known as “induced atmospheric vibrations.”
“These vibrations caused impairments in synchronization between the electrical systems and continuous failures across the entire interconnected European network.”
However, Ren’s spokesman Bruno Silva told AFP Tuesday that the grid operator “did not release this statement.”
