Hilbert-huang transform based islanding detection scheme for Distributed generation

This study presents a passive anti-islanding technique for distributed generation using Hilbert-Huang Transform (HHT). The voltage and current signals measured at point of common coupling of the distributed generator are processed through HHT to detect the islanding. Empirical mode decomposition (EMD) in combination with Hilbert transform can be termed as HHT. First, the EMD decomposes the signal into various intrinsic modes. Hilbert transformation is further performed over the modes extracted through EMD to obtain the analytic signal. Ratio index of voltage and current computed through HUT is used for identifying the islanding condition. Different simulation studies were performed during islanding condition with different power mismatches and also for non-islanding switching events. It is found that there is a reduction in non-detection zone compared to conventional rate of change of frequency (ROCOF) relay.