On the Impact of the Grid on the Synchronization Stability of Grid-Following Converters

The research on the synchronization stability of Grid-Following Converter (GFL) is of great significance for the stable operation of inverter-based resources. Existing literature mainly focuses the stability factors from the point of view of the converter and assumes the grid to be an infinite-bus with constant frequency. However, faults cause the grid to experience interdependent variations of grid voltage amplitudes and phases, as well as of its frequency. The impact of these variations on the synchronization stability has not been systematically and comprehensively studied yet. Here we study the combined effect on GFL synchronization stability of all these quantities following a large disturbance. The theoretical appraisal shows that phase-angle jump affects the initial perturbance of the GFL while the grid frequency affects the following transient responses and the stability boundary.Simulation results also show that the variation of the frequency with higher RoCoF may be beneficial for the stability of the GFL, and that the effects of the various of the voltage and frequency can be studied separately.