Threshold setting of an innovative anti-islanding relay for LV distribution systems by real time simulations

This paper proposes a procedure for determining the threshold settings of an innovative anti-islanding relay, named SmartID. The relay adopts a new patent-pending method based on the estimation of the parameters of a Thevenin-like model. The settings of the SmartID thresholds are determined by crossing the values of the estimated parameters, which are provided by repeated simulations of the typical LV systems in both gridconnected and islanded operation, accounting for various loading and DG operating conditions and of different SmartID installation points. The proposed procedure is tested by a laboratory set-up based on real-time simulations and the results show how the thresholds can adequately be determined to guarantee a reliable and secure detection of the islanding in LV distribution systems.