Behavior of synchronous generators, during the short duration voltage sags

Voltage sags are typically caused by fault conditions. The voltage sag condition lasts until the fault is cleared by a protective device. This paper describes the causes of voltage sags on the generators. It is observed that the armature current, voltage, torque, rotor angle, excitation current of the synchronous generator are also considerably affected by voltage sags. It is shown that shunt capacitors have an effect on the generator terminal voltage and the torque. It can be shown for a simple system that shunt capacitors affect the voltage sag and behavior of the synchronous generator. It is also observed that the electromagnetic torque of the generator is considerably affected by the voltage sag. The existence of shunt capacitors reduce the effect of voltage sag on both the terminal voltage and the torque of the machine.