<p>The increased penetration of distributed generators (DGs) within the power system reduces the system’s inertia and minimises the power mismatch between DGs and loads. This presents a critical challenge for anti-islanding protection to avoid failures to trip during island formation and nuisance tripping during grid disturbances. Anti-islanding protection that relies on impedance measurement offers a viable solution to these issues. However, existing methods are highly sensitive to factors such as the number of DGs and line impedance, and they struggle to establish a unified identification criterion across different islanded systems. To address this, an islanding identification criterion based on impedance angle variation measurement (IAVM) has been proposed in this work. The method’s adaptability is analysed by evaluating load switching, grid disturbances, and synchronisation deviations. Additionally, a signal synchronisation injection strategy is developed that utilises global positioning system (GPS) 1 pulse per second (1PPS) timing signals, incorporating this into the DG control strategy. Simulation experiments conducted on real-time digital simulator (RTDS) demonstrate that, compared to existing methods, the proposed approach can accurately identify islanding states under grid disturbances and zero-power mismatch islanding conditions. This method avoids issues related to refusal and nuisance tripping, while remaining unaffected by the number of DGs and the load capacity or other parameters.</p>