A power conversion apparatus performing power conversion between a DC circuit and an AC circuit, the power conversion apparatus comprising: power conversion circuitry including a plurality of sub-modules connected in series to each other; a control device configured to generate a control command for controlling operation of the plurality of sub-modules; and a relay apparatus configured to relay communication between the control device and the plurality of sub-modules, wherein for each sub-module of the plurality of sub-modules, the relay apparatus is configured to generate path information indicating a communication path from the control device to the sub-module, and outputs the generated path information to the sub-module, and each sub-module of the plurality of sub-modules includes an identification information generator configured to generate identification information of the sub-module based on the path information corresponding to the sub-module, a phase generator configured to generate a carrier phase based on the identification information and the number of sub-modules to be controlled among the plurality of sub-modules; and a PWM controller configured to perform PWM control on a switching device (22A, 22B) in accordance with the control command and the carrier phase. power conversion circuitry including a plurality of sub-modules connected in series to each other; a control device configured to generate a control command for controlling operation of the plurality of sub-modules; and a relay apparatus configured to relay communication between the control device and the plurality of sub-modules, wherein for each sub-module of the plurality of sub-modules, the relay apparatus is configured to generate path information indicating a communication path from the control device to the sub-module, and outputs the generated path information to the sub-module, and each sub-module of the plurality of sub-modules includes an identification information generator configured to generate identification information of the sub-module based on the path information corresponding to the sub-module, a phase generator configured to generate a carrier phase based on the identification information and the number of sub-modules to be controlled among the plurality of sub-modules; and a PWM controller configured to perform PWM control on a switching device (22A, 22B) in accordance with the control command and the carrier phase. for each sub-module of the plurality of sub-modules, the relay apparatus is configured to generate path information indicating a communication path from the control device to the sub-module, and outputs the generated path information to the sub-module, and each sub-module of the plurality of sub-modules includes an identification information generator configured to generate identification information of the sub-module based on the path information corresponding to the sub-module, a phase generator configured to generate a carrier phase based on the identification information and the number of sub-modules to be controlled among the plurality of sub-modules; and a PWM controller configured to perform PWM control on a switching device (22A, 22B) in accordance with the control command and the carrier phase. an identification information generator configured to generate identification information of the sub-module based on the path information corresponding to the sub-module, a phase generator configured to generate a carrier phase based on the identification information and the number of sub-modules to be controlled among the plurality of sub-modules; and a PWM controller configured to perform PWM control on a switching device (22A, 22B) in accordance with the control command and the carrier phase.