The converter station based on grid-forming control can provide voltage support for the renewable energy AC grid without conventional power supply support and AC main network connection in deserts

gobi

and barren lands of China

but its voltage support capability is constrained by current limiting. In this paper

a calculation method of short circuit ratio and critical short circuit ratio of renewable energy radial AC grid with grid converter providing voltage support is proposed. Firstly

the equivalent grid-connected current of the grid-connected point considering the influence of the injection current of the remaining nodes is derived. Secondly

the calculation of the supporting current of the system with current limiting link for renewable energy is obtained. Then

the calculation method of short-circuit ratio (SCR-I) and critical short circuit ratio (CSCRI) based on current calculation is proposed. By integrating the aforementioned elements

the grid voltage strength evaluation method is developed. Finally

the accuracy and rationality of using SCR-I and CSCRI to evaluate the voltage intensity of AC grid are verified by some examples.