Novel islanding detection method for distributed generation

This paper describes the development of a novel islanding detection method for inverter-based distributed generation, which uses the signal cross-correlation scheme between the injected reactive current and the power frequency deviation. The existing method injects the 5% reactive current to the rated current for detecting the frequency deviation, which brings about reduction of power quality. On the contrary, the proposed method injects the 1% reactive current to the rated current which brings about negligible degradation of power quality. The proposed method detects the islanding state by calculating the cross-correlation index between the injected reactive current and the frequency deviation. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software and experimental works with a 3 kVA hardware prototype. The proposed method can detect the islanding state effectively without degrading the power quality at the point of common connection point.