Momentary-voltage-drop compensation apparatus and momentary-voltage-drop compensation system

A momentary-voltage-drop compensation apparatus for supplying power to a load, by interconnecting a power system supplying alternating current (AC) power and a DC power supply supplying direct current (DC) power to the load, the momentary-voltage-drop compensation apparatus comprising:

• a system interconnection switch connected between the power system and the load;
• a first power converter that performs DC-AC conversion to the DC power of the DC power supply;
• a second power converter that includes
• a first terminal connected to the first power converter and the DC power supply, and
• a second terminal connected between the system interconnection switch and the power system,
• the second power converter performing AC-DC conversion to the AC power supplied from the power system;
• and
• a control unit that is connected to the first power converter, and is configured to control, in response to a detection of a voltage drop in the power system, the first power converter so as to output a zero-phase current, a current value of the zero-phase current being equal to or greater than a current value of a current flowing through the system interconnection switch.