This paper proposes an active islanding method based on impedance measurement for DC microgrids with multiple distributed generators (DGs). In the various presented methods

impedance-based islanding detection faces challenges in DC microgrids with multiple DGs due to the randomness of renewable energy. In the proposed method

the virtual impedance controls are designed to reshape the output impedance of DGs and the input impedance of loads at the detection frequency to ensure a clear distinction between grid-connected conditions and islanding conditions. Thus

the islanding events can be effectively detected under conditions that lead to a distinct decrease in system impedance. In this way

the accuracy of islanding detection is improved. Moreover

a dynamic allocation of the role algorithm is proposed to organize the orderly disturbance injection of DGs without communication

avoiding disturbance dilution. In addition

the selection principle of the frequency of disturbance current is proposed by studying the sensitivity of the point of common coupling (PCC) voltage to the disturbance. As a result

the negative influence of multiple DGs

loads

and disturbance dilution can be avoided compared to the existing methods. Finally

the effectiveness of the proposed method has been verified by both simulation and experimental results.