A unified damping controller for non-stationary forced oscillation

Forced disturbances (FDs) with non-stationary frequencies can sequentially resonate from electromechanical modes (EMs) to sub/super synchronous modes (SSMs) and thus lead to non-stationary forced oscillations (FOs). Previous FO damping controllers designed for specified frequency bands may not be able to suppress the non-stationary FOs. This paper proposes a unified FO damping controller design method to deal with all oscillations caused by non-stationary FOs. The model of a power system with non-stationary FOs is obtained by a continuous model detection and identification of measured signals, which does not require any value of the system parameters. Accordingly, four stability indices, i.e., robustness, interaction, frequency, and damping ratio of the EMs and SSMs, can be calculated from the estimated model. At each operating point, these indices are monitored and used to optimally design the unified FO damping controller. The effectiveness of the proposed unified FO damping controller is verified in the modified Southeast Australian power system with converter controlled-based generations under various operating points and FO conditions.