Since the wide application of virtual synchronous generators (VSGs), the power grid faces great challenges in the safe and stable operation due to their limited thermal capacity and weak anti-disturbance ability. During transient period, for example, a fault occurs in the transmission line, the VSG may lose the transient angle stability and provoke the current hard limit. Even if the fault is cleared by tripping of line, it still faces the problem of instability and voltage dips. To address this problem, in this chapter, the post-fault large-signal model of VSG is derived first via the travelling waves based fault information acquisition. Subsequently, with the effect of both active and reactive power loops taken into account, a two-stage simultaneous control scheme is proposed for improving the transient stability of VSG, while considering the current limitation during fault state and voltage support after fault clearance. This method is fulfilled by mode switching and an additional feedback control based on the fault signal. Finally, the effectiveness of the proposed method under both symmetrical and asymmetrical faults is verified. Moreover, the application of the proposed method in a multiple VSGs system is also verified. Besides, the robustness to parameter mismatch and the feasible operating region for the method are discussed. In order to avoid fault information, a non-fault information based dual-loop adaptive feedback control is proposed to take transient angle stability, current limitation and the demand of the reactive current of VSG into account. First the large-signal model of VSG with a dual-loop control is built. To design the feedback coefficients, the feasible coefficient region under different fault degrees and cases is analyzed subsequently. It provides reference for the curve fitting, which is further applied in the self-adaptive regulation of the feedback coefficients. Thereby, a dual-loop adaptive feedback control is realized based on an additional reactive power feedback loop. With the proposed control scheme, all of the three control objectives can be achieved without the fault information, since the feedback coefficients are within the feasible coefficient region by the self-adaptive regulation. Finally, the effectiveness and robustness of the proposed control scheme for both VSG and a paralleled system of VSG and grid-following (GFL) converter are validated by the simulation results and the experimental results.