We have studied bifurcations of the steady states in the power system with the generator model based on internal flux linkages of the generator. Although the power system is described by the thirteen first-order differential equation, bifurcations and steady states have been similar to those observed in low-dimensional systems. The mechanism of the voltage collapse in our system has been different from that of the references. It has been a unstable period-2 orbit that causes voltage collapse.
If change in voltage magnitude of the generator bus terminal is considered, the power system loses stability at the smaller value of reactive power in the load. When the system operates abnormally or before a voltage collapse occurs, the voltage magnitude of the generator bus terminal fluctuates largely rather than the angular velocity. From these results, dynamics in the terminal voltage of a generator is important.