A Realigned Instantaneous Frequency Approach for SSCI Oscillation Localization in Power Networks

The detection and localization of the grid oscillations stemming from subsynchronous control interactions (SSCI) presents notable challenges. These include the limited reporting rate of Phasor Measurement Units, spectral leakage, and picket fence effects, which inadvertently misreport the amplitude and frequency of modes constituting these complex oscillations. To accurately detect the oscillations and localize the participating sources, a systematic approach employing synchro-waveforms is proposed. Firstly, the modes of oscillations are extracted using a time-frequency transformation, where, a realigned instantaneous frequency-based synchro transform is developed to address noise and time-varying constraints. This is further improved by employing an adaptive window which improves the energy concentration to retain the reconstruction of modes for strongly time-varying signals with significant noise. A decoupled admittance model is then extracted from the modes obtained at varying operating conditions. Consequently, a global admittance matrix is constructed identifying the active/reactive source of complex oscillation in the network. The efficacy and robustness of the proposed method against the state-of-the-art are proven by employing numerical simulations on sample networks and real-world data obtained from networks experiencing SSCI oscillations.