A hybrid islanding detection technique for inverter-based distributed generator units

Due to high importance of islanding detection as an essential protection requirement, especially for the distributed generation (DG), a new approach to islanding detection is developed in the present paper. The method is based on a mixture of both active and passive algorithms, which uses voltage phase angle (VPA) and voltage unbalance (VU). The suggested method presents a combination of benefits of each individual passive/active method, and therefore it is useful to appropriately detect islanding situation in a wide range of scenarios. The use of the suggested method results in smaller nondetection zone (NDZ), faster response, and improved power quality. In order to illustrate the effectiveness of this approach, simulation results are provided under different conditions, showing that the suggested algorithm can reach the required islanding protection requirements. In addition, the performance of the proposed method and some other methods are compared by the presence of a variety of transient faults and insignificant power mismatch.