A power conversion device configured to perform power conversion between a DC circuit and an AC circuit , the power conversion device comprising: power conversion circuitry including a plurality of converter cells connected in series to each other, the converter cells each including an energy storage device and being configured to be capable of discharging stored energy; a control device configured to generate a control command for controlling operation of each of the converter cells; a protection device configured to generate a protection command for instructing whether to cause each of the converter cells to operate based on the control command or to stop operation of each of the converter cells regardless of the control command; and a repeating device configured to generate a control-and-protection command by combining the control command received from the control device and the protection command received from the protection device , the control-and-protection command being a combination of control information based on the control command and protection information based on the protection command, and output the generated control-and-protection command to each of the converter cells for every predetermined period, wherein the control device is configured to, for every first period (T1), generate a control command and output the generated control command to the repeating device, the protection device is configured, for every second period (T2), to generate a protection command and transmit the generated protection command to the repeating device, the second period (T2) being shorter than the first period, and the repeating device is configured to, for every third period (T3) as the predetermined period, generate a control-and-protection command based on the latest received control command and the latest received protection command, and output the generated control-and-protection command to each of the converter cells, the third period (T3) being shorter than the first period. power conversion circuitry including a plurality of converter cells connected in series to each other, the converter cells each including an energy storage device and being configured to be capable of discharging stored energy; a control device configured to generate a control command for controlling operation of each of the converter cells; a protection device configured to generate a protection command for instructing whether to cause each of the converter cells to operate based on the control command or to stop operation of each of the converter cells regardless of the control command; and a repeating device configured to generate a control-and-protection command by combining the control command received from the control device and the protection command received from the protection device , the control-and-protection command being a combination of control information based on the control command and protection information based on the protection command, and output the generated control-and-protection command to each of the converter cells for every predetermined period, wherein the control device is configured to, for every first period (T1), generate a control command and output the generated control command to the repeating device, the protection device is configured, for every second period (T2), to generate a protection command and transmit the generated protection command to the repeating device, the second period (T2) being shorter than the first period, and the repeating device is configured to, for every third period (T3) as the predetermined period, generate a control-and-protection command based on the latest received control command and the latest received protection command, and output the generated control-and-protection command to each of the converter cells, the third period (T3) being shorter than the first period. <EOS>