Voltage stability is the ability of a power system to maintain steady bus voltages within acceptable limits after a disturbance, which fundamentally depends on the system's ability to restore equilibrium between reactive power demand and reactive power supply (as distinct from rotor-angle stability, which concerns real-power/mechanical-electrical torque balance). The theory characterizes small-disturbance and large-disturbance voltage stability, models the load-voltage (PV/"nose curve") relationship for a simple source-load system to identify stable and unstable operating regions and a maximum deliverable power point, and defines voltage collapse as the cascading sequence of events (load loss, line tripping, generator tripping) that follows unchecked voltage instability. This is a subfield of power system stability analysis within electrical power engineering, closely coupled to but analytically distinct from rotor-angle stability.
Voltage stability is the ability of a power system to maintain steady bus voltages within acceptable limits after a disturbance, which fundamentally depends on the system's ability to restore equilib…