A device includes: a first power conversion circuitry configured to convert primary-side power into secondary-side power; and a control circuitry configured to: generate a command value associated with the secondary-side power; calculate a limited command value by modifying the command value so that the command value is equal to or less than a secondary-side limit, wherein the first power conversion circuitry is controlled based on the limited command value; transmit the limited command value to a second power conversion device comprising a second power conversion circuitry connected in parallel to the first power conversion circuitry; receive, from the second power conversion device, information indicating an adjustment value, wherein the adjustment value is added to the limited command value for controlling the second power conversion circuitry; and modify the secondary-side limit based on a difference between a primary-side limit associated with the primary-side power and the adjustment value.