Grid Incident in Spain and Portugal on 28 April 2025

1 MANAGEMENT SUMMARY 6
  1.1 Introduction 6
  1.2 System and Market Conditions Before the Incident 9
  1.3 System Conditions during the Incident 10
  1.4 Restoration Process 13
  1.5 RCC Analysis Before the Incident 13
  1.6 Communication of Synchronous Area Monitors and Between TSOs 14
  1.7 Classification of the Incident Based on the ICS Methodology 14
  1.8 Next Steps 14

2 SYSTEM AND MARKET CONDITIONS BEFORE THE INCIDENT 15
  2.1 Information on Topology 16
  2.2 Market Conditions 27
  2.3 Active Power Flows Before the Incident 27
  2.4 Inertia 35
  2.5 Oscillations 40
  2.6 Reactive Power and Voltages 66
  2.7 Behaviour of the HVDC Link 87
  2.8 Annex 97

3 SYSTEM CONDITIONS DURING THE INCIDENT 102
  3.1 Dynamic Behaviour of the System During the Incident 102
  3.2 Performance of the Protection System During the Incident 126
  3.3 System Defence Plan 170
  3.4 Impact of the Blackout on System Users on the French Network 179

4 RESTORATION PROCESS 180
  4.1 Preconditions and strategies for the restoration process 180
  4.2 Restoration sequences 183
  4.3 Generation and load recovery 206
  4.4 Steps after system restoration 212
  4.5 Market restoration 213

5 RCC ANALYSIS BEFORE THE INCIDENT 215
  5.1 Introduction 215
  5.2 RCC Tasks Relevant to the Investigation 218

6 COMMUNICATION OF SYNCHRONOUS AREA MONITORS AND BETWEEN TSOs 241
  6.1 Communication between TSOs 241
  6.2 ENTSO-E Awareness System (EAS) 252

7 CLASSIFICATION OF THE INCIDENT BASED ON THE ICS METHODOLOGY 255
  7.1 Scale of the Incident 256
  7.2 RCC Investigation Threshold 256
  7.3 Scale of all Violations Linked to the Incident 256

8 NEXT STEPS 259

LIST OF ABBREVIATIONS 260

EXPERT PANEL MEMBERS 262