Transient Stability Analysis and Enhancement of Grid-Following Converters Considering DC Voltage Dynamics Under Power Step

Existing transient stability analysis of grid-following converters mainly focused on the scenario of grid voltage faults, ignoring the potential transient instability caused by large power steps. However, it is found that grid-following converters may experience a loss of synchronization due to a large power step when considering DC voltage dynamics. To gain deeper insights into the transient stability of grid-following converters considering DC voltage dynamics, a fourth-order transient model is established, indicating that DC voltage dynamics not only worsen the damping characteristics of the phase-locked loop, but also increase the coupling effect of the grid impedance, thereby deteriorating the transient stability. Therefore, this paper proposes a transient stability enhancement method based on impedance voltage feedforward to effectively suppress the adverse effect of DC voltage dynamics on the transient stability, thus enhancing the transient stability of grid-following converters. Finally, simulation results validate the effectiveness of the proposed method.