Dynamic Mode Identification and Frequency Stability Enhancement for Grid-Forming Converters

Grid-forming (GFM) converters are expected to mitigate frequency variations and oscillations during grid contingencies. However, generic damping design of GFM converters cannot ensure frequency stability of power systems with spatial-temporal uncertainties. In this paper, the dynamic mode decomposition (DMD) method is introduced to extract frequency-domain dynamic modes from the time-domain frequency response of GFM converters during grid events. Even without access to detailed system configuration, dynamic modes enable GFM converters to assess frequency stability in a data-driven manner. This paper also proposes a damping enhancement method tailored for those critical modes with insufficient stability margin. The narrow band damping power introduced by a bandpass filter compensates for the damping of critical modes and mitigates both power and frequency oscillations.