METHOD FOR ISLANDING DETECTION OF GRID-CONNECTED ELECTRICAL POWER SYSTEMS

摘要

A phase shift procedure (62) for detecting a disconnect of a power grid (20) from a feeder (22) that is connected to a load (24) and a distributed generator (26). The phase shift procedure compares (76) a current phase shift of the output voltage of the distributed generator with a predetermined threshold and if greater, a command is issued (78) for a disconnect of the distributed generator from the feeder. To extend the range of detection, the phase shift procedure is used when a power mismatch between the distributed generator (26) and the load (24) exceeds a threshold and either or both of an under/over frequency procedure and an under/over voltage procedure is used when any power mismatch does not exceed the threshold.