Impedance-Adaptive Control Integrating DC-Link Voltage Synchronization Into Grid-Following Control

To suppress subsynchronous oscillation (SSO) in grid-following (GFL) converters in weak grids, this article proposes a control strategy that integrates DC-link voltage synchronization (DCVS) into the phase-locked loop. The system angle is formed as a weighted sum of the error signals from both. Through an analysis of the damping characteristics, a mapping between the weighting coefficients and grid impedance is established, enabling direct parameter calculation to meet a target damping ratio. Furthermore, a closed-loop adaptive control strategy is developed to handle varying short-circuit ratios. Finally, stability analysis and experimental results demonstrate that the proposed method effectively improves the small-signal stability of GFL converters against SSO under the investigated weak grid scenarios.