APPARATUS AND ISLANDING DETERMINATION METHOD FOR GRID DISTURBANCE

Apparatus and method for determining islanding of a system are provided. The method includes: calculating an amount of reactive power injection based on an active power command and reactive power command received from an upper controller of the distributed power; setting a failure confirmation count to 0; controlling injection of reactive power during a preset cycle among predetermined cycles of an AC voltage that is an output of the distributed power according to the failure confirmation count; measuring a frequency and angular frequency of the AC voltage, which is performed simultaneously with the injection of reactive power; and after the injection of reactive power is completed, increasing the failure confirmation count if a determination criteria based on the measurement of the frequency and the angular frequency of the AC voltage; and determining an islanding failure when the failure confirmation count reaches a preset value.