Identifying the presence of forced oscillations using oscillation signatures

Forced oscillations in a power system are distinguished from natural oscillations as a rouge oscillatory input to the system. Two examples for sources of these forced oscillations are a malfunctioning governor that has not been modeled or a cyclic load with a low frequency. Power system oscillations are analyzed either by model based methods or by measurement based methods. Several recent papers have studied the impact of forced oscillations in estimating small signal stability of a power system using measurement based methods. When the frequency of the forced oscillation is in the vicinity of natural oscillations in the system, it has been reported that estimating natural and forced oscillatory modes is a challenge. This paper proposes utilizing model data to generate a database of oscillation signatures of the system for different forced oscillations of different frequencies at different origins and, aid measurement based oscillation monitoring methods to determine frequency and damping of natural oscillations and the source of forced oscillations, including at resonant conditions.