“Iberian Peninsula blackout: analysis and performance of Nordex wind power plants”

The topic presented in the paper will show the analysis and performance recordings registered on Nordex wind power plants during the Iberian Peninsula blackout happened last April 2025.

On Monday April 28th at 12:33 PM, an unprecedented blackout affected the entire Iberian Peninsula, including Spain, Portugal and a small part of south-west France. This event was the first "zero energy" case in the Iberian region's history.

Firstly, the paper will analyze what was the Iberian grid situation before the blackout, the high penetration of renewables (70%) and the system inertia values observed. Moreover, an overview on power oscillations observed 30 and 10 min before the event will be included. The oscillations affected the whole European continental grid and were correctly controlled and dampened. However, power oscillations were not seen during the blackout, so they could be not directly related to it.

Secondly, the paper will summarize what was the sequence of events. The blackout was caused by a cascade disconnection of generation plants in the southern and western regions of Spain. This cascade disconnections of generation power plants caused a significant power imbalance, making the grid frequency decrease to less than 47Hz in less than 5s and RoCoF to less than -4Hz/s, what motivated the disconnection from the European continental grid and from Morocco and finally caused the complete collapse of the Iberian electrical system.

Entering more technical details, the paper will compare ENTSO-e and REE published sequence of events with the recordings from one of the Nordex’s wind power plants operating close to where the blackout was originated. The detailed graphical comparison of the voltage and frequency recordings available from 20s before the blackout until the system collapse will show a significant match with the sequence of events declared by REE and ENTSO-e.

The root cause analysis investigation done by REE and Spanish government is still ongoing, and new small pills of information are released every week. The paper will summarize the official information available. In the moment of this abstract presentation, the main root cause of the blackout was a cascade of disconnecting of generation plants due to overvoltage. Discussions regarding the responsibility of the wrong voltage control are on-going between the main Spanish electrical energy companies, REE and local distribution system operators. Moreover, the power generation spinning reserve planned by REE for that moment seemed to be not enough to compensate the unexpected big loss of generation. Other possible hypothesis like an unusual atmospheric phenomenon, cyberattack or lack of inertia due to the big share of renewables seem to be discarded.

Finally, the paper will show how Nordex wind farms operated during the event, injecting all available power from the wind during all the event and only disconnecting when the grid voltage and frequency went out from the operating ranges required by the grid code and the whole system collapsed. In addition to this, an overview on the historical use in Spain of existing system services of Nordex wind power plants like voltage control or spinning reserve will be shown, offering existing and future solutions that Nordex’s wind power plants could provide to prevent from similar blackout events in the future.