Experimental verification of a new positive feedback islanding detection method for grid-connected inverter

Islanding detection is one of the most important issues for grid-connected inverter applications. a new positive-feedback anti-islanding method is presented in this paper. it utilizes the negative sequence voltage component as a positive feedback variable,and no additional negative sequence disturbance is needed at all. after islanding,the positive feedback loop will force the negative sequence voltage component away from the nominal value. a new negative sequence estimation algorithm is also presented for the successful islanding detection. finally,the experimental tests are carried out to verify the effectiveness of the proposed method.