A passive islanding detection index based on variation of signal energy

A new index for passive islanding detection is proposed. The approach exploits the inherent harmonic distortion produced by grid-connected power converters as well as the frequency dependent changes in the grid impedance as seen by the distributed generator before and following islanding. The new index is computed from the variation of signal energy over a certain band of frequencies contained within a virtual power signal. The virtual power signal is obtained from measurements of voltage and current at the point of common coupling. The approach is validated via simulation and is demonstrated on a 7kW distributed generator system.