A novel active islanding detection method based on current-disturbing

Desired islanding detection method not only can detect islanding within acceptable duration, but also require it has less adverse impact on power quality. This paper presents an active islanding detection method for a distributed resource (DG) unit which is coupled to a utility grid through grid-connected converter. With the proposed method which is based on adding periodical disturbing current through current controller of the interface voltage-sourced inverter, islanding can be effectively detected. But when the disturbing current remains unchanged, this method still has some shortages, so this article improved it and used a changed time-varying disturbing current ending with faster detecting time and less disturbing. The studies reported in this paper are based on time-domain simulations in the PSCAD/EMTDC environment. And the results show that the proposed islanding detection method always meets the two-second UL detection requirement.