A study on islanding detection function and FRT function of hysteresis control inverter powers in digital grid

In this study, the authors aim to develop the interconnection inverter called “Proton” used for the “Digital Grid” which has been proposed as a new electric power grid. The authors propose an islanding detection function and fault ride thorough (FRT) function of interconnection inverter. In the proposed method, the output current is controlled to be proportional to the voltage of the grid. During the momentary voltage drop, the output current of the inverter is decreased, and when the grid recovers, the output current is increased to the rated value automatically. The proposed method satisfies FRT requirement without any complicated detection and system stop process. The numerical calculation is carried out in order to verify the validity of the proposed method.