Large-scale new energy bases are usually located in remote areas where the local grid is relatively weak. The adoption of grid-forming control for wind and solar renewable energy and VSC-HVDC converters aids in providing frequency and voltage support. Current research on grid-forming strategies mainly focuses on the AC side grid-forming performance of the converter

ignoring the impact of DC side dynamic process

thus hindering the explanation and suppression of oscillation problems caused by DC dynamics. Therefore

this paper establishes a full-order model of a two-stage grid-forming converter considering pre-stage control and DC bus voltage dynamics. Through eigenvalue analysis

it is found that DC voltage dynamics can cause the power-angle-related poles of the post-stage grid-forming converter to move to the right half-plane

thereby leading to low-frequency oscillations. To suppress the low-frequency oscillations caused by DC voltage dynamics

this paper proposes a transient damping optimization strategy based on the feed-forward excitation controller of DC voltage dynamics

which can effectively suppress the low-frequency oscillations caused by the coupling interaction between the pre-stage and post-stage. Finally

the accuracy of the proposed model and the effectiveness of the optimization strategy are verified through simulations.