Research on a novel islanding detection technique

Inadvertent islanding causes serious problems. For these reasons islanding detection is an indispensable feature for distributed generation systems. In this paper, the non-detection zones (NDZs) of over/under voltage (OUV) and over/under frequency (OUF) method are analyzed in ΔP versus ΔQ space. And the Slip-mode frequency shift (SMS) method is discussed. The non-detection zones of the SMS in the Q_f versus f₀ space is analyzed. In order to overcome the disadvantage of SMS, an adaptive sliding-mode frequency shift (ASMS) 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 at the point of common coupling is accelerated, and the time of islanding detection is shortened. The Simulation and experimental results are given to verify the theoretical analysis.