构网直流支撑的新能源辐射型汇集系统短路比指标分析OA

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.