The outage of lines 6 and 21 triggers a cascade,
resulting in the simultaneous outage of a large number of lines.
This eventually leads to the system splitting and to the disconnection
of a significant amount of load. It can be seen that the
amount of load shedding needed increases as the disturbance
unfolds. This shows the impact of delayed and ineffective operators’
reaction due to their inability to form an accurate picture
of the system immediately after the initial line failure. This
case is similar to the Italian blackout of 2003 [4], where ineffective
cooperation between the Italian and Swiss operators led
to delayed actions, resulting in the