A new control method in PV grid connected inverters for anti-islanding protection by impedance monitoring

This paper proposes a new control method for the single phase PV grid connected inverters. The proposed method injects interharmonic test current for measuring the impedance of the public grid to detect islanding situation. The proposed control system employs two PI controllers to generate the reference current separately for the fundamental frequency and interharmonic current, and finally applies a dead beat predictive control to determine the duty cycle of the switches. The grid impedance is measured simultaneously with injection of the interharmonic current using DFT algorithm.