The Asociación Española de Empresas Eléctricas (AELEC), which includes major electricity providers such as Iberdrola, Endesa, and EDP, has requested that the investigation into the electrical blackout that affected the Iberian Peninsula and Portugal on April 28 also examines the "extreme and widespread" voltage fluctuations observed earlier that month.

AELEC's statement, released on Tuesday, highlights that significant variations in voltage were detected between April 22 and April 24, which triggered the automatic disconnection of generation installations and customer services.

In particular, the association mentions incidents such as those affecting the Cartagena refinery in the Region of Murcia and high-speed rail lines operated by Adif, which attracted media attention.

Concurrently, the European Network of Transmission System Operators for Electricity (ENTSO-E) has initiated its own investigation into the blackout, expressing concern that the preliminary timeline only focuses on the 20 seconds preceding the event and does not take into account the previously noted voltage oscillations.

AELEC has reported that ENTSO-E indicated there were no oscillations at the time of the incident and that the electrical system variables were within normal operational ranges.

However, AELEC contends that conditions were unstable during the morning of April 28, noting that in the seconds prior to the blackout, voltage levels exceeded emergency thresholds.

Specifically, the connection points with the transmission grid began showing increased voltage instability from 10:00 AM.

According to AELEC, voltage levels recorded just before the blackout dropped to zero at 12:33 PM, while they had approached 250 kilovolts (kV) on a network with a nominal voltage of 220 kV, leading to automatic disconnections in accordance with safety protocols.

The association emphasizes the need for the investigation to encompass not only that morning but also the preceding days to assess the origins of the voltage fluctuations experienced.

In response to AELEC's claims, representatives from Red Eléctrica have denied the assertions, stating that voltage levels prior to the incident did not exceed the established limits for the 400 kV and 220 kV nodes.

They reference Operating Procedure 1.4, which outlines permissible voltage ranges and the obligations of connected installations to withstand these levels without damage or disconnection.

Red Eléctrica also states that there were no oscillations detected and that system variables were within acceptable thresholds.

Furthermore, they argue that earlier days' conditions cannot be correlated with the incident on April 28, as the electrical system configuration was different.

They have assured that all information concerning those days has been submitted to the relevant authorities and that investigations into the circumstances surrounding the April 28 blackout, including the electrical variables in other networks and infrastructures outside regulator oversight, are being conducted thoroughly.

In a separate development, the Partido Popular (PP) plans to leverage its absolute majority in the Senate to establish a committee to investigate the management responsibilities related to the April blackout.

PP spokesperson Alicia García emphasized the need for clarity on what transpired and the government’s proposed measures to prevent future occurrences.

The formation of this investigative committee is set to take place alongside an inquiry targeting the vice president and Minister for Ecological Transition, Sara Aagesen.

On the same day, there will be a monographic session in the Senate focused on the blackout.

Additionally, the PP intends to propose an independent audit of the government’s findings regarding the blackout's causes, as well as explore measures that may include extending the operational life of nuclear plants to avert future power outages.

In defense of the government, Vice President Aagesen stated that the government acted appropriately in response to the unprecedented blackout.

She indicated that efforts were focused on restoring power to affected citizens and formulating emergency measures.

Aagesen described her night spent at Red Eléctrica’s control center to ensure operational integrity and maintain power supply, asserting that the government is rigorously investigating the blackout's causes to implement measures preventing future incidents of this nature.