This paper studies the influence of conventional fault ride through strategy on the stability of VSG large disturbance under extremely weak grid and severe grid voltage dip condition. First

the grid-forming characteristic characterization model of VSG under conventional fault ride through strategy is derived theoretically. On this basis

the concept of fault ride through feasible region is further proposed in considering the conditions required for successful fault ride through. The feasible region defines the application range of the conventional VSG fault ride through strategy in the case of different severity level faults. In addition

to solve the problem that conventional strategy cannot ride through different severity level faults successfully

this paper proposes an enhanced VSG fault ride through strategy based on dynamic current-limiting voltage control unit. With the flexibility of near-area reactive power and far-area voltage control

VSG can effectively improve its support ability to grid voltage while limiting short-circuit current effectively under extremely weak grid condition. Finally

simulation is constructed in PSCAD/EMTDC

and the effectiveness of the proposed control strategy is verified.