Spain’s countrywide blackout on Monday has demonstrated the vulnerability of so-called “island” and peninsular grids, despite international improvements in redundancy and forecasting capabilities in recent years, Montel Analytics Director, Jean-Paul Harreman has said (words: Montel Analytics).
Earlier on Monday, Spain and parts of Portugal and France experienced a major power outage, causing widespread disruption across all three countries. The affected TSOs have not yet revealed what they believe caused the outage, with Spanish TSO Red Electrica saying restoration of full power may take “6-10 hours” in Spain.
Harreman said that while the outage was an “unprecedented event in modern energy markets”, the blackout occurring in Spain and Portugal is “not particularly surprising”, as “countries that are on the edge of, and more isolated from the synchronous European grid tend to more easily see grid frequency deviations”.
“In island systems like GB and Ireland, or peninsular systems like Italy and Spain, the AC synchronous interconnectivity with other countries is much lower, leading to a more vulnerable grid as flexibility and resilience has to mostly come from the inside,” he said.
International comparison
By contrast, a country like Germany is “surrounded by many other countries and connected with AC connections, in which assets operate that provide resilience to the grid frequency”, which needs to be kept at 50 Hz at all times to prevent blackout.
“Whenever there is a deviation due to a power plant outage… there is sufficient flexible capacity to ‘catch’ the frequency before it goes ‘out of bounds’,” he said. “This buys time to bring up other generation capacity to fill the gaps or take other measures.”
He noted that a blackout of this scale has not been seen since the 2003 Great Italian blackout, or the Turkish blackout of 2015.
Synchronous generation
Synchronous power generation is the process where generators produce electricity at a constant speed so that their output frequency remains synchronized with the grid’s frequency. This is normally provided by conventional power stations including nuclear, gas and coal.
The inertia provided by these power station types helps the grid ride out disturbances including to the frequency. Modern power sources like wind and solar are not synchronous.
Complex markets
Energy markets remain a complex subject as they are affected by the underlying AC power physics, Harreman concluded, where through European cooperation the energy transition has “taken great leaps”, but also where “some parts of the grid do not completely benefit from the scale of the European market completely and as it is not easy to add more AC interconnection into areas like Spain and Portugal, but also GB, Ireland, Italy and Denmark”.
“Extreme variations”
Portuguese grid operator REN said “extreme variations” in Spain’s temperature caused the power failure, though Spanish TSO Red Electrica has so far given no reason for the outage.
“It will be interesting to read about the atmospheric phenomenon that was observed today and the likelihood of this occurring again in the future,” said Harreman, referring to the theory that extreme variations in temperature were responsible.
Phil Hewitt, director at Montel Analytics also added: “Grid disturbances can be ridden out to a degree in regular times but on this occasion, there was a lot of non-synchronous generation on the network which made it more vulnerable.
“Grid operators need to invest in inertia technologies like synchronous condensers to support the drive for more renewables. Investment in fast acting balancing reserves such as batteries also provides extra resilience as we have seen in markets like GB and Ireland.”
