In order to study the influence of VSC control loop on the stability of DC voltage control in weak-grid

a time-scale small signal model of VSC DC voltage in weak-grid was established firstly. Based on the analysis of dynamic characteristics

the stability of VSC DC voltage control was characterized by using damping components and restoring components. Moreover

under different strengths and different grid control bandwidths

the influence law of the VSC phase-locked loop and AC voltage control loop on the damping component and restoring component was studied

and the influence mechanism of the phase-locked control and AC voltage control on the DC voltage stability was revealed. Finally

a detailed time-domain simulation model was constructed on the Matlab/Simulink

and the stability analysis results were verified. The research results show that

in a weak grid

the phase-locked control and AC voltage control play a lag role in DC voltage control of phase

and negative additional damping components are generated

which damages the stability of DC voltage control.