People wait at Sants train station in Barcelona, Spain, during a power outage. (Photo: Gian Marco Benedetto/Anadolu via Getty Images)
On Monday morning, April 28, a rare international power outage affected all of Spain and Portugal, as well as parts of southwestern France.
The outage caused major disruption to the region, with airports suspended, people stranded in the Lisbon and Madrid metros and hospitals forced to close.
The cause of the power outage remains unclear, although officials from Portugal's energy provider Redes Energéticas Nacionais (REN) said on Monday that it was due to a rare phenomenon known as “induced atmospheric vibration.”
“The abnormal oscillations on the very high voltage (400 kV) lines were caused by extreme temperature variations within Spain, known as 'induced atmospheric vibration',” REN told the Guardian. “These oscillations led to synchronisation failures between electrical systems, causing consequential disruptions across the interconnected European network.”
However, REN later refuted this explanation, as reported by Euronews.
“The power outage that affected mainland Portugal today was caused by significant voltage fluctuations in the Spanish power grid when Portugal was importing electricity from Spain,” REN said in a statement on Monday afternoon. “These fluctuations caused the control and protection systems of the Portuguese power plants to shut down, causing the power outage.”
Extreme temperature fluctuations can cause unusual oscillations in very high voltage power lines, physically moving back and forth. This is due to temperature changes causing the lines to expand in some places, changes in the tension and aerodynamic properties of the lines, and interactions with wind and electrical current, which can physically and electrically destabilize the power grid.
“While investigations are ongoing, some early media reports point to a phenomenon known as 'induced atmospheric vibration', which is associated with unusual atmospheric conditions including sharp temperature variations and associated wind patterns in inland areas of Spain,” said Victor Becerra, a professor in the Department of Power Systems Engineering at the University of Portsmouth in the UK.
“If such conditions were present, they could cause abnormal oscillations in very high voltage power lines,” Becerra added.
This could result in broken wires, short circuits, or damage to infrastructure such as power line pylons.
“The protection systems are designed to automatically shut down affected power lines if such faults occur,” Becerra explained.
Then there’s a domino effect of sorts, with outages causing instability and shutting down some generators. “The loss of large generators can create a sudden and significant imbalance between the supply and demand of electricity in the grid, which can lead to widespread outages,” Becerra said.
However, the exact cause of the outages has not been confirmed, and some other experts have suggested that it could have been the result of a cyber attack. However, there is no evidence to support this theory, European Commission Senior Vice-President Teresa Ribera told Spanish Radio 5 on Monday. On Tuesday, April 29, Eduardo Prieto, head of services at Spanish grid operator Red Eléctrica, told the Guardian that they had ruled out a cyber-security incident.
Whatever the initial cause, such a large region was affected because European power grids are tightly interconnected. This usually provides greater reliability, as other grids can provide backup power in the event of local problems. But it also makes the entire system vulnerable to major failures that cover a much larger area.
«
Sourse: www.livescience.com
