The Comisión Nacional de los Mercados y la Competencia has opened separate investigations into the Ascó nuclear power plant and the Mequinensa and Riba roja hydroelectric plants to investigate if their operation could have had any influence on the electrical zero of April 28 of last year. The existence of these actions was confirmed by the CEO of Endesa, José Bogas, during his appearance before the Congress commission that analyzes the blackout.
The administrative investigation seeks to clarify if the company could have incurred in any serious infraction of the Electricity Sector Law in the management of these facilities, in their maintenance or in their operating conditions. The maximum period to resolve the files is 18 months.
Open investigation on Ascó, Mequinensa and Riba roja
The regulations to which these actions refer frame this type of possible non-compliance in cases where there are no circumstances of risk for the guarantee of supply nor serious danger or harm to people, property or the environment. In this case, the files focus on determining if there were serious irregularities in the operational or maintenance scope.
"No Endesa facility contributed to the destabilization of the system or to the blackout" - Endesa sources
The company also maintains that all open files are for serious and not very serious offenses, and defends that they are linked to operational or maintenance issues, not to the blackout itself. Along the same lines, it highlights that Ascó, Mequinensa and Riba roja had no role in the destabilization of the system on April 28 at 12:00.
Endesa adds that another distinct issue is the review of possible non-compliances in the two previous years, an aspect that is also under analysis. Red Eléctrica, for its part, has certified that the three facilities complied with all the requirements at that moment.
Without a closed cause for the blackout
For now, none of the open investigations to determine the origin of the electrical zero have managed to establish a conclusive cause. The technical and political debate remains open while the electrical system faces a scenario of constant transformation, with greater operational complexity and increasing volatility of tensions.
That context has reopened the discussion about the response capacity of strategic power plants in case of a widespread incident. At this point, black start has become a key element to recover service after a severe interruption.
Only three strategic power plants of Lleida can self-start
Of the 47 hydroelectric plants in Lleida cataloged as strategic by Red Eléctrica, only three have self-starting systems. These are those of Bossòst, Aiguamoix and Pont de Rei, located in the Garona, capable of resuming their operations without external support after an interruption.
The documentation of the Ebro Hydrological Plan places the Sant Joan de Toran power plant, also in the Garonne, as non-self-starting, along with 43 other facilities. All of them need external support, either through generator sets or through energy from other power plants, to return to service.
- 17 power plants in the Pallaresa basin
- 9 power plants in the Segre basin
- 17 power plants in the Ribagorçana basin
These 47 hydroelectric plants are part of the service restoration network in case of a national or zonal incident. Their function is to power the auxiliary services of the thermal generation units, ensure the safe shutdown of nuclear power plants, and recover the interconnection with the European synchronous system. In that framework, the robustness of the system and the real startup capacity of strategic facilities are once again at the center of the analysis while investigations into what happened on April 28 remain open.