Ideal Power Inc.
Anti-Islanding Systems and Methods Using Harmonics Injected in a Rotation Opposite the Natural Rotation

Abstract:

An active anti-islanding architecture where a power converter injects a current component at a harmonic of the fundamental power frequency is injected with a phase sequence opposite to that which normally be present with that harmonic. (For example, a 5.sup.th harmonic frequency can be used with a positive phase sequence, or a 7.sup.th harmonic frequency with a negative phase sequence.) The injected current component can have a thousandth or less of the power transferred by the converter, since the distinctive phase sequence of the injected signal facilitates recognition of a corresponding term in the observed voltage.