Enphase Energy, Inc.
Method and apparatus for activation and de-activation of power conditioners in distributed resource island systems using low voltage AC

Abstract:

Method and apparatus for controlling power conditioners in a distributed resource island. In one embodiment, the method comprises comparing, at a power conditioner operating in a de-energized state, an input of the power conditioner to an input threshold, wherein the power conditioner is coupled to an islanded grid; operating the power conditioner, when the input exceeds the input threshold, in a soft-grid mode to generate a touch-safe AC voltage that is coupled to the islanded grid; and activating the power conditioner, based on an impedance of the islanded grid and load demand for the power conditioner, to operate proximate its nominal output voltage.