Power conversion device

A power conversion device connected to an AC system and equipped with virtual synchronous generator control, the power conversion device comprising:

• a converter to convert a first DC voltage output from a distributed power source into a second DC voltage;
• an inverter to convert the second DC voltage output from the converter into an AC voltage and output the AC voltage to the AC system;
• a communication circuit to receive information necessary for the virtual synchronous generator control given from a management device that manages the distributed power source;
• a first voltmeter to measure the second DC voltage;
• a second voltmeter to measure an AC system voltage of the AC system;
• a converter control circuit to control the converter;
• a virtual synchronous generator control circuit to impart a transient characteristic of a synchronous generator to the inverter;
• and
• an inverter control circuit to control the inverter as a voltage source, based on AC system voltage information input from the virtual synchronous generator control circuit, wherein
• the information necessary for virtual synchronous generator control includes a power target value of the power conversion device,
• the virtual synchronous generator control circuit calculates a switching frequency at which charge/discharge of the distributed power source is switched, based on the information necessary for virtual synchronous generator control, and
• the converter control circuit uses the switching frequency to create a frequency range of the AC system voltage for providing a dead zone in which charge/discharge power of the distributed power source is zero in a drooping characteristic of the power conversion device, or a hysteresis in switching of charge/discharge of the distributed power source, and the converter control circuit performs control such that charge/discharge power of the distributed power source becomes zero in the frequency range.