42.Define Stability? What is the two kind of stability?

Stability of a generator is defined as its ability to remain in synchronism with the power system to which it is connected.

The two regimes of stability are :

1. Steady state stability
2. Transient stability

The Steady stability of a generator defines its ability to remain in synchronism under the conditions of steady state operation. In practice, this also includes load drift, voltage drift and small fairly slow load changes.

Transient stability defines the ability of the generator to return to its former state of stable operation after having been disturbed from this state due to sudden changes of loading or voltage conditions. The type of changes included here are those due to power system faults, load swing, sudden tripping of sections of power system network, etc.