This example is composed by the 11-bus 4-machine 2-area system, where these two areas are connected via weak tie lines. This test system is ideal for studying dynamic stability, power interchange, oscillation damping, etc.
The four generation units are composed of machines and exciters, differently from the system Two_Areas_PSSE.
The system undergoes a three-phase-to-ground fault on Bus 8 at 3s, lasting for 200ms. Simulate the system for 10 seconds. Variables of interest are the ones related to inter-area modes. For example:
g1.g1.SPEED
g2.g2.SPEED
g3.g3.SPEED
g4.gENSAL.SPEED
which are variables that represent the generator's deviation from nominal speed, in per unit. Note that generators 1 and 2 swing together, while swinging against generators 3 and 4. This is due to coherency between the area's group of generators.
Compare these results with the ones from Two_Areas_PSSE.