ABSTRACT
In order to distinguish between the cases of continuously and non-continuously acting voltage regulators, it is useful to consider a typical case where a single large generator is connected by to large power system through a double circuit transmission line. Because of the importance of system damping in dynamic stability, it is important to identify and account for significant sources of system damping. Historically, synchronous machine excitation systems used a direct current (DC) generator to power the field circuit and many of these systems are still in common use today. Alternating current (AC) excitation systems have basically replaced DC excitation systems in modern turbine generator installations. A small AC pilot exciter energizes the stationary field winding of the AC exciter. The term static excitation implies that all the active components of these systems are static or stationary. The oscillatory response of most excitation systems has prompted the use of additional means to enhance their behavior.
