Power conversion device

A power conversion device for connecting a distributed power source to a grid power source, the power conversion device comprising:

• a voltage detection unit configured to detect a voltage value of output voltage of the power conversion device;
• a current detection unit configured to detect a current value of output current of the power conversion device;
• a constant power factor control unit configured to control a power factor of output power of the power conversion device such that the power factor becomes equal to a preset power factor command value by injecting reactive power to a grid power source side based on the detected voltage value and the detected current value;
• and
• an islanding operation detection unit configured to:
• calculate a variation amount of frequency of grid voltage of the grid power source from a cycle of voltage waveform detected by the voltage detection unit, and
• determine whether the power conversion device is in an islanding operation mode based on the variation amount of frequency of the grid voltage after injecting the reactive power having an amount associated with the calculated variation amount to the grid power source side,
• wherein the constant power factor control unit controls a power factor of output power of the power conversion device based on the detected voltage and current values at a second moment in time that is earlier than a first moment in time by a preset reference time period, with the first moment in time being a moment at which the detected voltage and current values are acquired to control the power factor.