Effect of angle regulator on power system stability

RECENTLY there has been considerable discussion of the benefits with respect to electric power system stability to be obtained by the use of a properly designed angle regulator. An angle regulator applied to a synchronous machine is defined here as a regulator that varies the machine excitation voltage in response to changes in the angle between the rotor interpole axis and the effective system voltage so as to tend to restore the initially set angle. The purpose of this article is to present the results of an analytical exploration of the possibilities of the angle regulator as regards stability. In particular, since voltage regulators already are used extensively, and since their use as aids in power-system stability already has been studied, it has seemed appropriate to compare the action of an angle regulator with that of a voltage regulator.