Patent ID: 9742192
Date: 2017-08-22
CPC Classifications: G01R,H02J

Claim:
1. A method of detecting island formation in a distributed power system including at least one distributed generator interruptably coupled to a grid through a feeder, the method comprising: using a frequency measurement device to compile a set of values of the rate of change of frequency (RoCoF) in the power system at a plurality of instants in time, measured over a predetermined time window; using a processor to group the set of RoCoF values into a plurality of histogram bins, at least a first pattern of RoCoF values grouped into one of the histogram bins and representing an expected behavior of power frequency change when the feeder is grid-tied, and at least a second pattern of RoCoF values grouped into at least another one of the histogram bins and representing an expected behavior of power frequency change when the feeder is islanded; using the processor to apply a predetermined decision criterion to the histogram bins to determine whether the feeder is islanded or grid-tied; and automatically decoupling the distributed generator from the feeder if the feeder is determined to be islanded according to the predetermined decision criterion.