Power conversion device and power conversion system including a power converter capable of converting between alternating-current (AC) power and direct-current (DC) power

A power conversion device, comprising:

• a power converter capable of converting an AC power into a DC power or converting a DC power into an AC power;
• and
• a control device that controls the power converter, wherein
• the power converter is interconnectable to an AC system via an AC circuit breaker, and a DC terminal of the power converter and a DC terminal of another power converter are connectable,
• the power converter includes a plurality of arms connected in parallel between a positive DC bus and a negative DC bus,
• the plurality of arms each include a positive arm and a negative arm connected in series, and a point of connection between the positive arm and the negative arm is connected to each phase AC line,
• the positive arm and the negative arm each include one or more transducer cells connected in series,
• the transducer cells each include
• a series body which includes a plurality of semiconductor switching elements connected in series, and
• a DC capacitor connected in parallel with the series body,
• the power converter begins operation prior to the other power converter,
• the control device controls a voltage of the DC terminal of the power converter, based on a status of the other power converter, and
• the control device and the other power converter directly communicate with each other.

A power conversion device, comprising:

• a power converter capable of converting an AC power into a DC power or converting a DC power into an AC power;
• and
• a control device that controls the power converter, wherein
• the power converter is interconnectable to an AC system via an AC circuit breaker, and a DC terminal of the power converter and a DC terminal of another power converter are connectable,
• the power converter includes a plurality of arms connected in parallel between a positive DC bus and a negative DC bus,
• the plurality of arms each include a positive arm and a negative arm connected in series, and a point of connection between the positive arm and the negative arm is connected to each phase AC line,
• the positive arm and the negative arm each include one or more transducer cells connected in series,
• the transducer cells each include
• a series body which includes a plurality of semiconductor switching elements connected in series, and
• a DC capacitor connected in parallel with the series body, wherein
• the power converter begins operation prior to the other power converter,
• the control device notifies another control device that controls the other power converter of a status of the power converter, and
• the control device and the another control device directly communicate with each other.