Research on the adaptive slip-mode frequency shift method

Inadvertent islanding causes serious problems. For these reasons islanding detection is an indispensable feature for DG-systems. The Slip-mode frequency shift(SMS) method was discussed. And the non-detection zones of the SMS in Q_f×f₀ coordinate system was analyzed. In order to overcome the disadvantage of SMS, an adaptive sliding-mode frequency shift method is proposed. This method sets the starting angle. When the measured frequency deviation is beyond the error range, the maximum phase angle and starting angle will be increased in the positive feedback manner. Thus, the frequency deviation of point of common coupling is accelerated, and the time of islanding detection is shortened. The experimental results verified the validity of the proposed method.