With the growing penetration of renewable energy power generation in the power system

the synchronization stability problem of voltage source converter(VSC) has become increasingly prominent under fault conditions. To further reveal the synchronous instability mechanism of the VSC during faults and enhance its synchronous stability

this paper studies in detail the synchronous stability problem of VSC during the low voltage ride-through(LVRT).Firstly

referring to the synchronous generator(SG)

the equivalent rotor swing equation of VSC is established. Consequently

the large/small disturbances synchronization stability mechanism of VSC can be revealed under a severe symmetric grid fault.The analysis results clearly show that the deep voltage sag

improper current instructions

large transmission line impedance

and inappropriate controller parameters would all deteriorate the synchronization stability of VSC.Furthermore

a synchronization stability improvement control strategy based on automatic voltage regulation is proposed

which can not only generate additional virtual torque

and virtual damping to enhance the the large disturbance synchronization stability of VSC

but also increase the damping ratio to improve the small disturbance synchronization stability of VSC.Finally

the simulation results validate the validity of the proposed strategy.