AN ANTI-ISLANDING METHOD BASED ON SYMMETRY OF A LINE FREQUENCY

摘要

Disclosed are a module to detect isolated operation using the symmetry of power frequencies and a method to detect isolated operation using the same. According to an embodiment of the present invention, the module to detect isolated operation using the symmetry of power frequencies includes a detection unit which receives each of output current data from a first and a second distributed power inverter connected in parallel, samples the data, and detects a positive half cycle frequency and a negative half cycle frequency according to the output currents of the first and the second distributed power inverter; a calculation unit which calculates difference between the amplitude of the positive half cycle frequency and the amplitude of the negative half cycle frequency; an index calculation unit which calculates and outputs an isolated operation determination index using the difference; a comparison unit which compares the isolated operation determination index, to which the difference is applied, and a predefined reference determination index and, if the isolated operation determination index, to which the difference is applied, is greater than the reference determination index, determines that the module is in an isolated operation state and outputs a processing signal; and a control unit which controls the operation of the first and the second distributed power inverter according to the reception of the processing signal.