Frequency monitoring of forced oscillation in PMU's data from NASPI

This paper presents a systematic approach to detect the frequency of Forced Oscillation (FO) in real-time signals obtained from phasor measurement units (PMUs). It is shown that, preprocessing of the signal by Empirical Mode Decomposition (EMD) technique leads to effective detection. The designed methodology can detect the frequency of FOs even in the presence of multiple mode mixing, whereas the self-coherence method fails to detect. Spectral analysis is performed on the Intrinsic Mode Functions (IMFs) to determine the frequency of FO. To further confirm the sustainability of the oscillation, spectral analysis of time-delayed signals is also performed and the results are discussed. The study is investigated on both simulated signal and real-time PMU signal of North American SynchroPhasor Initiative (NASPI). Two forced oscillations; FO 1 (14.67 Hz) and FO 2 (4.62 Hz) are detected in the NASPI PMU's signal by the proposed approach.