A power duplication apparatus for a High Voltage Direct Current (HVDC) system, comprising: a first independent power generator for receiving first input power and generating and outputting first power; a second independent power generator for receiving second input power and generating and outputting first power; a first power supply for selectively receiving the first power individually output from the first independent power generator and the second independent power generator, converting the received first power into second power having a magnitude less than that of the first power, and outputting the second power; a second power supply for selectively receiving the first power individually output from the first independent power generator and the second independent power generator, converting the received first power into second power having a magnitude less than that of the first power, and outputting the second power; a first HVDC controller configured to be activated by receiving the second power from the first power supply and to control an HVDC converter; a second HVDC controller configured to be activated by receiving the second power from the second power supply and to control the HVDC converter; and a power monitoring controller for comparing a magnitude of the first power with a magnitude of pre-stored first reference power, and for, when first power having a magnitude differing from the magnitude of the first reference power is present, allowing first power output from the first independent power generator or the second independent power generator, which generates the first power having a magnitude identical to that of the first reference power, to be transferred to the first power supply and the second power supply, wherein the power monitoring controller comprises a switch, which includes a first contact terminal, a second contact terminal, a third contact terminal, wherein the first contact terminal is connected to the first HVDC controller, the second contact terminal is connected to the second HVDC controller, and the third contact terminal is connected to the HVDC converter and is selectively connected to the first contact terminal or the second contact terminal under control of the power monitoring controller. a first independent power generator for receiving first input power and generating and outputting first power; a second independent power generator for receiving second input power and generating and outputting first power; a first power supply for selectively receiving the first power individually output from the first independent power generator and the second independent power generator, converting the received first power into second power having a magnitude less than that of the first power, and outputting the second power; a second power supply for selectively receiving the first power individually output from the first independent power generator and the second independent power generator, converting the received first power into second power having a magnitude less than that of the first power, and outputting the second power; a first HVDC controller configured to be activated by receiving the second power from the first power supply and to control an HVDC converter; a second HVDC controller configured to be activated by receiving the second power from the second power supply and to control the HVDC converter; and a power monitoring controller for comparing a magnitude of the first power with a magnitude of pre-stored first reference power, and for, when first power having a magnitude differing from the magnitude of the first reference power is present, allowing first power output from the first independent power generator or the second independent power generator, which generates the first power having a magnitude identical to that of the first reference power, to be transferred to the first power supply and the second power supply, wherein the power monitoring controller comprises a switch, which includes a first contact terminal, a second contact terminal, a third contact terminal, wherein the first contact terminal is connected to the first HVDC controller, the second contact terminal is connected to the second HVDC controller, and the third contact terminal is connected to the HVDC converter and is selectively connected to the first contact terminal or the second contact terminal under control of the power monitoring controller.