Impedance-based analysis of active frequency drift islanding detection method for grid-tied inverter system

This paper presents an impedance-based analysis of active frequency drift (AFD) islanding detection method for grid-tied inverter systems. To study the AFD islanding detection method, output impedance of grid-tied inverter is modeled. Islanding detection is analyzed using the interaction between inverter output impedance and load impedance. The analysis further shows that the AFD islanding detection method has the potential to destabilize the grid-connected inverter system when the grid is weak or the size of inverter is large. Experimental results verified the analysis.