Voltage oscillatory instability caused by induction motor loads

Isolated power systems which fit the structure of a single equivalent generator supplying an equivalent composite load can experience a voltage oscillatory instability entirely traceable to effects of induction motor loads interacting with automatic voltage regulators. This scenario is one where an AVR properly tuned for open circuit conditions is not necessarily well tuned for the on load condition. The phenomenon is explained and a simple solution through AVR compensation is suggested.