Comparative Evaluation of Damping Control Strategies in GFM Converters: Insights for Wideband Oscillation Mitigation

Grid-forming (GFM) converters with cascaded control loops might induce small-signal instability issues over a wide frequency range, and existing damping control strategies are usually designed and verified for oscillations in specific frequency bands, exhibiting limited integrity in wideband small-signal stability assessments. In this paper, detailed control structures are considered for small-signal modeling to reveal potential wideband oscillation modes in the GFM converter systems. Then, systematic evaluation and comparison of various damping control methods are carried out regarding their positive impacts and side effects on different oscillation modes, thereby providing an integrated solution capable of mitigating instabilities over a wide frequency range. The theoretical analysis results are verified by simulations and experimental tests.