Evaluation of Superimposed Sequence Components of Currents based Islanding Detection Scheme during DG Interconnections

A new islanding detection scheme for distribution network containing different types of distributed generations (DGs) is presented in this paper. The proposed scheme is based on acquiring three phase current samples for full cycle duration of each simulation case of islanding/non-islanding conditions at the point of common coupling (PCC) of the targeted DG. Afterwards, superimposed positive & negative sequence components of current are calculated and continuously compared with pre-determined threshold values. Performance of the proposed scheme has been evaluated on diversified islanding and non-islanding events which were generated by modeling standard IEEE 34-bus system using PSCAD/EMTDC software package. The proposed scheme is capable to detect islanding condition rapidly even for perfect power balance situation for both synchronous and inverter based DGs. Furthermore, it remains stable during non-islanding events such as tripping of multiple DGs and different DG interconnection operating conditions. Therefore, the proposed scheme avoids nuisance tripping during diversified non-islanding events. At the end, comparison of the proposed scheme with the existing scheme clearly indicates its advantage over the existing scheme.