A Hybrid Islanding Detection Technique Based on Active Current Injection and ROCTHD for Multi‐DER Based Microgrid

In multi‐distributed energy resource (DER) based microgrids, accurate islanding detection is critical to ensure personnel safety, equipment protection, and overall system stability. However, existing methods often struggle to reliably detect islanding under non‐detection zone (NDZ) conditions and may suffer from false detections during non‐islanding events (NIEs) such as load or capacitor switching. To address these limitations, this paper proposes a novel hybrid islanding detection technique combining passive and active approaches. The passive component utilizes the rate of change of total harmonic distortion (ROCTHD) to monitor voltage and current signals for islanding detection across various load conditions, including NDZ scenarios. However, to mitigate the possibility of false positives where NIEs are misclassified as islanding events (IEs) the method integrates an active current injection mechanism. This active component is triggered only when the passive method indicates a potential IE, thereby confirming the condition with minimal system disturbance. The proposed hybrid method is implemented in a multi‐DER (MDER) test system modeled in MATLAB Simulink and validated using a real‐time simulator (OP4510). The results demonstrate that the technique offers fast and more reliable islanding detection compared to traditional methods, with high accuracy under a wide range of operating conditions and negligible disruption during non‐IEs.