From Newsgroup: sci.electronics.design

On 2025-06-17 21:38, Carlos E.R. wrote:


"This is the report paid for by Iberdrola and Endesa. Coincidentally, it was presented three days before the official ENTSOe report."

No blame on renewables.


<https://www.comillas.edu/noticias/el-iit-presenta-un-informe-preliminar-que-analiza-las-causas-del-apagon-del-pasado-mes-de-abril/>

The IIT presents a preliminary report analysing the causes of last April's blackout
29 September 2025

Large voltage fluctuations, low synchronous generation and a weak transmission network are some of the causes

The Institute for Technological Research (IIT) at Comillas Pontifical UniversityrCoone of Europe's leading electrical systems research centresrCohas today published an independent preliminary report analysing the causes of the blackout that left the Iberian Peninsula without power on 28 April. The document, prepared by professors Luis Rouco, Enrique Lobato and Francisco M. Echavarren, concludes that the blackout was the result of a combination of voltage instability in the previous days, insufficient synchronous generation, an insufficient safety margin against overvoltage collapse and a weak transmission network, aggravated by the disconnection of renewable generation and operational manoeuvres that reduced the safety margin.


The analysis reveals that synchronous generation (mainly combined cycle and nuclear power plants) in the southern and central areas was unusually low, with only one combined cycle plant in Andalusia and one nuclear plant in the centre. In addition, more than a third of the 400 kV grid was disconnected for maintenance or voltage control, leading to poorly damped oscillations.

The report introduces the concept of rCyovervoltage collapserCO, a phenomenon unprecedented in Europe, where voltage increases uncontrollably when renewable generation is disconnected. It adds that the cascading overvoltage that occurred is unprecedented in the European electricity system.

The researchers also emphasise that the manoeuvres carried out by Red El|-ctrica de Espa|#a between 12:00 and 12:30 rCoconnecting lines to try to dampen the oscillationsrCo further reduced the safety margin, accelerating the collapse of the system.

The IIT recommends reviewing the criteria for synchronous generation scheduling and voltage control procedures, especially in scenarios of high renewable penetration, and urges the use of more advanced metrics to anticipate risk situations. The report also highlights the importance of strengthening coordination between the various players in the electricity sector and adapting the operation of the system to the new challenges of the energy transition, with the massive integration of renewables.



Translated with DeepL.com (free version)
--
Cheers, Carlos.
ESEfc-Efc+, EUEfc-Efc|;
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