Patent ID: 8681515

Claim:
An energy generation system having an anti-islanding protection function, the energy generation system comprising: an inverter configured to convert a DC voltage supplied from energy source into an AC voltage; a three-phase/two-phase transformer configured to transform a three-phase output of the inverter into a two-phase stationary coordinate system; a phase locked loop configured to calculate a phase and frequency of an output voltage of the inverter using a two-phase voltage outputted from the three-phase/two-phase transformer; a phase shifter configured to selectively compare the frequency of the output voltage of the inverter with a plurality of mutually different threshold values through use of the frequency of the output voltage outputted from the phase locked loop and a current amplitude reference value applied from an exterior, and to generate a current phase reference value for shifting an output phase of the inverter; a current reference coordinate transformer configured to transform the current phase reference value outputted from the phase shifter and the current amplitude reference value into a two-phase stationary coordinate system through use of a phase angle outputted from the phase locked loop; a current phase calculator configured to subtract a phase component of output current of the inverter, which is outputted from a current two-phase transformer, from the current phase reference value in the two-phase stationary coordinate system outputted from the current reference coordinate transformer, and to output a current phase calculation value; a current amplitude calculator configured to subtract an amplitude component of output current of the inverter, which is outputted from the current two-phase transformer, from the current amplitude reference value in the two-phase stationary coordinate system outputted from the current reference coordinate transformer, and to output a current amplitude calculation value; a current adjuster configured to generate a current adjustment signal using the current phase calculation value and the current amplitude calculation value; an output three-phase transformer configured to transform the current adjustment signal in the two-phase stationary coordinate system, which is outputted from the current adjuster, into a current adjustment signal in a three-phase stationary coordinate system; and a PWM controller configured to output a PWM control signal to the inverter using the current adjustment signal in the three-phase stationary coordinate system, which is outputted from the output three-phase transformer.