  This paper proposes a novel hybrid approach for islanding detection of
inverter-based distributed generations (DG) based on combination of the Slip
mode frequency-shift (SMS) as an active and rate of change of frequency (ROCOF)
relay and over/under frequency relay as passive methods. This approach is
utilized to force the DG to lose its stable operation and drift the frequency
out of the allowed range of the frequency threshold. Performance of the
proposed approach is evaluated under the IEEE 1547, UL 1741 and multiple-DG
operation. The simulation results demonstrate the effectiveness of the proposed
approach for detection of islanding, especially for loads with high quality
factor. It operates accurately under the condition of load switching and does
not interfere with the power system operation during normal condition. In other
words, not only it holds the benefits of both SMS and ROCOF, but also it
removes their drawbacks by having less non-detection zone and faster response.
