Harmonic current based islanding detection for grid connected PV systems

In this paper, an improves islanding detection technique for grid connected photovoltaic systems is proposed based on the harmonic current produced by the inverter. The inverter is controlled using constant current control scheme by injecting harmonic current signal generated from the system itself. So this detection technique has the benefits of both passive and active detection methods such as power quality enhancement and reduction of non-detection zone (NDZ) respectively. The proposal is validated through simulation studies in a single phase grid connected Photovoltaic system and the islanding operation is detected in a very short time, with reduction in the NDZ compared to the conventional current control method.