Impedance and Damping Characteristics of Grid-Connected VSCs With Power Synchronization Control Strategy

Modeling and analysis of the output impedance of a grid-connected voltage-sourced converter (VSC)-based system under the recently-developed power synchronization control topology is presented in this paper. The impact of impedance passivity on subsynchronous damping profile of an electrically-nearby synchronous generator is then characterized. The impacts of key factors such as control modes and control parameter are addressed. A comparison with the standard vector control strategy is also presented. The results reveal that under this type of control, a VSC does not have negative impact on sub-synchronous dynamics; on the contrary, it has a positive impact, compared with commonly used vector current control where the latter has a potential to degrade the system damping. Time-domain simulation results are presented to validate the theoretical analysis.