The existing grid-connected guidelines require that the new energy unit outputs a reactive current proportional to the voltage drop at the grid-connected point during the short-circuit fault

so that the unit can support the voltage at the grid connection point during low-voltage-ride-through (LVRT). However

in some fault situations such as three-phase grounding short circuit fault

using a fixed proportional factor (K-factor) may still result in synchronization instability. Therefore

this paper focuses on the influence of the LVRT control strategy based on K-factor on transient synchronous stability (TSS)

and proposes an improved LVRT control strategy. Firstly

from the perspectives of static equilibrium point and dynamic stability region

the feasible region of K-factor under LVRT control is derived

and the transient synchronous instability mechanism of the converter is revealed. The negative correlation between K-factor and frequency is pointed out. On this basis

this paper proposes an LVRT control strategy based on adaptive K-factor adjustment

thereby ensuring the existence of equilibrium point during transient process of new energy units and improving the TSS performance. The effectiveness of the proposed strategy for improving the TSS of the grid-connected converter is verified by simulation and StarSim control in-loop experiment.