Grid Impedance Impact on the Maximum Power Transfer Capability of Grid-Connected Inverter

This paper analyzes the maximum power transfer capability of the grid-connected renewable energy generation system, which is mainly influenced by the short circuit ratio (SCR) and the resistance-inductance ratio (R/X) of grid impedance. It is revealed that an inverter connected to the AC grid with a larger SCR or a smaller R/X ratio has more power transfer capability. Besides, it is found that the critical conditions for the inductive grid and the resistive grid are different. Under an inductive grid, SCR = 1 is a critical point for effective power transmission. However, under a resistive grid, the SCR needs to be at least higher than 5 for effective power transmission. Finally, simulation results verify the effectiveness of the analysis.