A bilateral reactive power injection method for islanding detection of grid-connected converters in distributed generation units

In this paper, a bilateral reactive power injection method is proposed for islanding detection of grid-connected converters in distributed generation units. The proposed method injects capacitive and inductive reactive power periodically with half of the grid frequency to perturb the frequency of point of common coupling (PCC). The magnitude of the injected reactive power is derived in order to remove the non-detection zone and the frequency of the injected reactive power is determined by considering parallel operation of the converters with no communication. In addition, the distortion of the currents by the proposed detection method is analyzed. The effectiveness of the proposed method is experimentally verified through the operation of two converters used for a 10kW battery energy storage system.