Tracking Periodic Voltage Sags via Synchrophasor Data in a Geographically Bounded Service Territory

Existing methods for synchrophasor data analysis focus on oscillations that can be interpreted as a sum of sinusoids with or without damping, however, they are more difficult to apply when considering other types of waveforms. This paper investigates how to apply spectral estimation analysis methods when analyzing a periodic voltage sag whose waveform is comparable to a periodic pulse train. A methodology is proposed where the estimated power spectral density and spectrograms are used to detect the area impacted by a periodic sag and to identify its dominant propagation path, which helps with the localization of the disturbance's spread. The proposed methodology is applied to measurement data obtained from a region in Dominion Energy's service territory that is geographically bounded by other utilities, which validates the effectiveness of the proposed method in a real-world utility setting.