Abstract: The present invention relates to a modular apparatus for a high-voltage direct-current transmission system. A sub-module (10), which is a modular apparatus, comprises according to the present invention a power unit (12) in the front and a capacitor unit (13) in the rear, and on the lower end of a front surface (14?) of a power unit housing (14) forming the exterior of the power unit (12) is a sloped surface (15). The sloped surface (15) has a hexahederal shape created by removing the edge formed by the front surface (14?) and the bottom surface of the power unit housing (14) and faces the ground at an angle. A display unit (16) is provided on the sloped surface (15) so that the status of the sub-module (10) can be easily checked by a worker from the ground on which a structure stands.

Abstract: The present invention relates to a converter for electric power having multiple sub-modules connected in series, the sub-modules having an energy storage unit and multiple power semiconductor circuits connected in parallel to the energy storage unit, and which causes an electric current to bypass a sub-module in case the breakdown of the sub-module occurs. To this end, the converter for electric power according to the present invention has multiple sub-modules connected to each other in series, the sub-modules having an energy storage unit and at least one power semiconductor circuit that is connected in parallel to the energy storage unit and comprises multiple power semiconductor switches and freewheeling diodes, wherein each of the sub-modules comprises a bypass switching unit, which is connected in parallel to any one of said at least one power semiconductor circuit, and bypasses an electric current via the bypass switching unit.

Abstract: A technology is disclosed for controlling switching of power converters included in a power converting system. Phase angles are allocated to a plurality of sub-units corresponding to the power converters, and the respective sub-units create local switching carriers based on the allocated phase angles. The sub-units compare a reference AC voltage with the local switching carriers, and switch the power converters according to the result of the comparison.

Abstract: The present invention relates to a converter for electric power having multiple sub-modules connected in series, the sub-modules having an energy storage unit and multiple power semiconductor circuits connected in parallel to the energy storage unit, and which causes an electric current to bypass a sub-module in case the breakdown of the sub-module occurs. To this end, the converter for electric power according to the present invention has multiple sub-modules connected to each other in series, the sub-modules having an energy storage unit and at least one power semiconductor circuit that is connected in parallel to the energy storage unit and comprises multiple power semiconductor switches and freewheeling diodes, wherein each of the sub-modules comprises a bypass switching unit, which is connected in parallel to any one of said at least one power semiconductor circuit, and bypasses an electric current via the bypass switching unit.

Abstract: A technology is disclosed for controlling switching of power converters included in a power converting system. Phase angles are allocated to a plurality of sub-units corresponding to the power converters, and the respective sub-units create local switching carriers based on the allocated phase angles. The sub-units compare a reference AC voltage with the local switching carriers, and switch the power converters according to the result of the comparison.