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This paper presents a hybrid islanding detection technique for grid connected Distributed Generations (DGs). The proposed scheme is based on three different decisive factors which are derived from negative sequence voltage (NSV) by applying Hilbert transform, Wavelet transform and standard normal distribution function. Different types of non-islanding and islanding events have been simulated by modeling IEEE 34-bus system using PSCAD/EMTDC software package. The performance of the proposed scheme has been evaluated on large number of cases which are generated by varying load and fault parameters. The simulation results indicate that the proposed scheme is able to detect islanding situation accurately even under perfect power balance condition. Moreover, the proposed scheme provides better stability in case of specific type of non-islanding event i. e. fault on adjacent feeder during which most of the existing scheme issues nuisance tripping. Furthermore, it provides satisfactorily results during change in network topology and also at different values of X/R ratio of DG. At the end performance of the proposed technique is also comprehensively compared with the schemes currently reported in the literature. This comparison apparently demonstrates the advantages of the proposed technique over existing schemes.

This article proposes a new Karl Pearson’s coefficient of correlation (‘r’) based islanding detection scheme which utilizes negative sequence voltage and voltage unbalance signal. In order to check the legitimacy of the proposed technique, large numbers of non-islanding and islanding events are generated by modeling IEEE 34-bus network. This scheme detects islanding situation even under 0 % power mis-match condition and thus, reduces the non detection zone (NDZ). Furthermore, the proposed technique detects islanding situation quickly as well as remains stable during the critical non-islanding situation like faults on adjoining feeder having varying location and fault resistance. Moreover, the proposed technique remains immune to variation in external system condition and fundamental frequency. The performance of the proposed technique is comprehensively compared with the schemes currently reported in the literature. This comparison apparently demonstrates the benefits of the proposed technique over existing schemes.