Comparative Assessment of Spectral Analysis Methods for Characterizing Forced Oscillation

The oscillations in a power system can be catego-rized into free oscillations and forced oscillations. Forced oscil-lations (FOs) are caused due to periodic forced disturbance. It has been reported that estimating natural and forced oscillatory modes is problematic when the frequency of the forced oscillation is close to that of the system's natural oscillations. Hence, FOs are now becoming a highly concerned phenomenon in the power system. In this paper, a systematic comparative assessment is presented based on power spectrum estimation analysis between the Welch periodogram and the Multitaper method (MTM). Besides, if not properly taken into account, the calculation of the mode and mode estimation of low frequency oscillation may be adversely affected by forced oscillation. Forced oscillations must quickly be identified and mitigated, otherwise the persistence of FO may lead to severe damages to the system equipment and protective devices consequently leading to blackout.