Regulation of a 115-megawatt turbogenerator

A 115-MEGAWATT 95-per-cent power-factor generator, having a short-circuit ratio of 0.66, has lost synchronism occasionally during faults in the 20 years it has been in service at the Waukegan Station of the Public Service Company of Northern Illinois. During faults the the generator terminal voltage became so low that the generator lost a large share of its load and the rotor accelerated, thus allowing the generator to swing out of synchronism. It was decided to investigate possibilities of using automatic voltage regulation to maintain generator voltage.