Non-detection zone determination and islanding detection for constant current inverter based distributed generation

In this paper¡ at first¡ the non-detection zones (NDZ) of under/over voltage relay have been determined for constant current inverter based DG and then¡ an islanding detection method is presented using this relay. In the presented method¡ the DG direct current reference has a fixed value in normal condition¡ if the point of common coupling (PCC) voltage changes¡ Idref is determined as a linear function of PCC voltage. In this method¡ Idref is determined in terms of Idref0 and local load direct current axes adaptively. The proposed method is evaluated in islanding and non-islanding conditions¡ using PSCAD/EMTDC and MATLAB software. Simulation results show that the proposed method has a proper operation in the islanding and non-islanding conditions.