Analysis of the synchro-phasor measurements of the power system oscillations involved in the Iberian Peninsula blackout

Abstract

At 12:33 on 28th April 2025, a blackout occurred in the Iberian electricity system. Sixty million people lost the electricity supply. This is the first time in the history of the Spanish peninsular electricity system that a blackout has occurred. It is only comparable in continental Europe in terms of severity to the blackout of the Italian system on September 28, 2003. Although the trigger of the blackout was a cascading series of generation disconnections and voltage increases, the system conditions were affected by actions taken by the Spanish TSO to mitigate two episodes of sustained power system oscillations (one 0.6 Hz and the other 0.2 Hz) that occurred minutes earlier. This contribution will present an analysis of the synchro-phasor measurements of the power system oscillations involved in the Iberian Peninsula blackout. In particular, the controversy about the nature of the 0.6 Hz oscillation will be reviewed and discussed.