Abstract: A system and method test sustained and anti-islanding capabilities of EUT, where a power island is sustained without anti-islanding functionality and becomes de-energized with anti-islanding functionality. The method includes applying grid voltage to the EUT to obtain measurement current from the EUT; calculating RLC component values of a programmable RLC filter from measurement current and source voltage, including calculating target gain and phase, calculating target R, L and C parameters using the target gain and phase, and translating the target R, L and C parameters to physical parameters; applying the physical parameters and the measurement current to the programmable RLC filter to obtain RLC voltage; comparing the RLC voltage to source voltage; and when the RLC voltage is substantially the same as the source voltage, predicting that transition to a power island with the applied RLC component values will be sufficiently smooth to avoid triggering system protections of the EUT.