Coordinated operation of parallel-connected inverters for active islanding detection using high frequency signal injection

The high frequency impedance measured at the terminals of inverters connected in a microgrid by means of the injection of a small magnitude, high frequency voltage, has been shown to be a reliable metric to detect islanding. While the implementation of this method is simple when only an inverter injects the high frequency signal, this case is of limited applicability. On the other hand, several concerns arise when multiple inverters work in parallel, primarily due to risk interference among inverters. Islanding detection using high frequency signal injection in microgrids with multiple parallel-connected inverters is studied in this paper. A strategy for the coordinated operation of the inverters, without the need of communications or pre-established roles is proposed. Simulation and experimental results will be provided to demonstrate the viability of the concept.