Periodic injection of a second harmonic component with Fourier isolation for the detection of power islands

Distributed Generation (DG) systems include several technologies, many based on renewable energy sources. Due to the intermittent nature of many DG systems, it is necessary to include energy storage devices. This results in a multitude of DG units that require grid connection. Single phase power converters are necessary to achieve connection between domestic scale DG units and the grid. The majority of utility connection standards state that the DG unit must detect a loss of mains (LOM) event and stop feeding energy into the grid. This paper presents a laboratory setup that has been specifically designed to verify the adherence to grid connection standards. Multiple in-the-loop based LOM detection methods are presented, analysed and compared. A harmonic injection technique is introduced and its merits discussed. (5 pages)