Active islanding detection method for inverter-based distribution generation power system

► A virtual capacitor based islanding detection method is proposed. ► The inverter acts as a virtual capacitor when the utility is interrupted. ► The proposed detection method can detect the islanding operation effectively. A novel islanding detection method for an inverter-based distribution generation power system is proposed in this paper. The inverter-based distribution generation power system includes a dc power source and a grid-connected DC/AC inverter. The grid-connected DC/AC inverter acts as a virtual capacitor as the frequency is slightly lower than the fundamental frequency of utility voltage. Since only the inverter-based distribution generation power system supplies power to the load as the utility power interruption occurs, the virtual capacitor operation of the inverter-based distribution generation power system will result in the change of load voltage in amplitude or frequency. Hence, the proposed method can immediately detect the islanding operation.