For the operation conflict problems existing between islanding protection(IP)and fault ride-through(FRT)function of inverter interfaced distributed generator(IIDG)

an impedance characteristic based coordinated operation method for IP and FRT of IIDG is proposed. Based on the transfer function analytical model of equivalent impedance at point of common connection(PCC)

the impedance characteristics under conditions of grid-connected and islanding operation are analyzed. The simultaneous detection of islanding and transient voltage disturbance in the same inverter is achieved according to the variable features of PCC harmonic impedance

thus the IP and FRT functions are performed correctly. Example analysis shows that the proposed method is able to effectively identify islanding and transient voltage disturbance

while coordinating the IP and FRT functions. It has better compatibility for available FRT and dynamic reactive power support methods. Thus

it is beneficial for IIDG to actively participate in grid regulation and better adapt to high penetration integration in distributed networks.