Transient synchronization stability analysis of grid-following converter with frequency control

With the large-scale integration of renewable energy sources, power systems are increasingly characterized by low inertia. Under grid faults, system frequency is prone to rapid variations, which activates the frequency control mechanisms in power electronic converters. However, the activation of these control loops may have non-negligible impacts on synchronization stability. This paper investigates the transient synchronization stability of grid-following (GFL) converters considering frequency control. An equivalent nonlinear model is developed to characterize the synchronization dynamics between the converter and the grid. Based on this model, the influence of the frequency control on the transient synchronization stability of the grid-connected GFL converter under grid faults is analyzed. The study reveals that the existence of equilibrium points depends on grid impedance and fault severity. Besides, increasing the primary frequency control gain can enhance system damping and suppress oscillations, whereas excessive inertial control gain may reduce system damping and compromise the transient stability margin. This paper provides guidance for parameter tuning of frequency control in GFL converters. Also, the time-domain simulations are conducted to validate the theoretical analysis.