In order to clarify the comprehensive operating range of grid-connected inverters under weak grid conditions considering multiple constraints

firstly

we analyzed the critical short-circuit ratio (SCR) of the grid-connected system under three individual constraints

namely

voltage limit violation

maximum power transfer

and small-signal stability. Subsequently

we put forward a comprehensive critical short-circuit ratio (CSCR) by integrating these three constraints

while revealing the dominant constraint determining the system’s CSCR. Then

the terminal voltage compensation strategy was adopted to re-evaluate the CSCR of the compensated system. Research results demonstrate that

in uncompensated scenarios

the system’s CSCR is mainly constrained by voltage limit violation. After implementing terminal voltage compensation targeting this primary constraint

the system only needs to consider small-signal stability constraints

thus the CSCR is reduced and the overall operating range is expanded. Simulations and hardware-in-the-loop experiments verify the correctness of the theoretical analysis.