Saturation in synchronous machines due to voltage sags

Voltage sags and voltage interruptions are huge power quality problems for many industries. Voltage sags cause, apart from eventual tripping, flux saturation, which cause large currents. This paper illustrates how the stator flux in a synchronous machine changes during voltage sags. It is shown that for some voltage sags, there will be flux saturation. Flux saturation causes both large currents and torque; these may quicken the aging of the machine. A comparison is done with a model without saturation included. This study includes only three-phase symmetrical voltage sags.