If you are using the RMS simulation, you can export the angles of both generators in text file and compute the angular difference externally.

Or you can also connect PLL at the synchronous generator buses you desire and use it to measure the rotor angle difference.

I used the internal command to get Maximum rotor angle but I am confused that it never goes beyond 360, although the system is unstable. It should go beyond 360 when unstable. Can u please help in this

Please look at the book (Electric Machines)

by

Sarma

from

Northeastern University

I think that this is because the mechanism in the powerfactory makes the generator out of slip when the rotor angle reaches -180 or 180 degrees. Have you found a solution so the generator doesn't get out of slip?