Manuel Alcázar Ortega
Full Professor, Deputy Head of the Department of Electrical Engineering at the School of Industrial Engineering of the Polytechnic University of Valencia and Academic Director of the Degree in Energy Engineering
Is the report based on sound data and methods?
“The report is based on the ICS (Incident Classification Scale) method, established by ENTSOE to, amongst other objectives, systematically analyse the causes of incidents that may occur in the electricity grid. Consequently, the incident that occurred in the Iberian system has been analysed by a panel of 49 experts in accordance with this method. The data analysed consisted mainly of that requested from both transmission and distribution network operators”.
What new insights does it provide?
“The report concurs with that produced by Red Eléctrica in June 2025 in that the blackout was caused by a voltage problem, which led to a cascade disconnection of several generators due to their protection systems tripping. Without delving into the causes behind the voltage rise, the ENTSOE panel points to the ineffectiveness of voltage control in the Spanish electricity system as the key reason why the blackout could not be prevented.”
What results or data would you highlight?
“Voltage control in the system failed for three reasons:
- Some conventional generators capable of dynamic voltage control did not perform this function as required.
- Renewable generation does not provide voltage control.
- The System Operator did not have time to activate the manually operated compensation elements, some of which had been deactivated by a previous undervoltage event.
Furthermore, the report notes an inappropriate setting of the trip values for the overvoltage protection systems.
Regarding the frequency oscillation that occurred subsequently, it is emphasised that, whilst the loss of generation led to an increase in system frequency, the loss of synchronism could not have been avoided, even if the system’s inertia had been greater, given the speed at which a point of no return was reached.”
What practical recommendations can we make or highlight based on this report?
“It appears that the full report identifies a series of recommendations in Chapter 9, which are not mentioned in the summary provided. As Red Eléctrica has already pointed out, one of the first actions should be to review the voltage control operating procedure (P.O. 7.4).”