I am performing a simple work to evaluate the transitory stability of the system shown attached when a three-phase fault happens in the substation S. Osorio. Due to this fault three-lines shown in the picture have been cut off from the system. Now the system lost its synchronism, I need to find a way to make it come back to synchronism again. I was trying to cut off the generation that is attached to the S. Osorio bus, but according to the simulation I'm doing that is not the solution of the problem because the machine's angle grows forever to different directions. I would like to know if you have some tip on what to do to keep this system operating without the 3 line transmissions.