Bifurcation-Based Transient Stability Analysis of Grid-Forming Converters with DC-Link Voltage Controller

Transient stability of grid-forming (GFM) converters has drawn increasing research interests in the last few years, while the impact of DC-Link Voltage Controller (DVC) on the transient stability of GFM converters remains an open issue. To bridge this research gap, this paper presents a design-oriented transient stability analysis of GFM converters with DVC. A large-signal model is established first. Based on this model, the parametric effects of DVC on the transient stability are evaluated by phase portraits and further confirmed by simulation tests. It is revealed that the increase of proportional gain of DVC would enhance the transient stability. The mechanism of the parametric effects is theoretically explained based on the bifurcation theory. Finally, experimental tests are performed to validate the effectiveness of the theoretical analysis.