That graph doesn't seem to make a very clear distinction between historical, real-time and predicted values... I think the event happened at 12:30 local time or so.
There seems to be some kind of recurrent daily pattern where the French - Spanish interconnect switches from Spain -> France imports to France -> Spain exports at around that time, and then back again in the late afternoon.
There seems to be some kind of recurrent daily pattern where the French - Spanish interconnect switches from Spain -> France imports to France -> Spain exports at around that time, and then back again in the late afternoon.