FIELD: electrical engineering, in particular, low-voltage assembly of main transformer of transformer station. SUBSTANCE: device has two frequency converters, and high-frequency stepping-down transformer which is inserted between them. First frequency converter increases mains frequency as multiple to number of phases, and is equipped with direct voltage circuit using controlled rectifier and inverter. Second frequency converter decreases frequency down to frequency of mains and is designed as zero cycle converter with natural switching. Rectifier control circuit provides possibility of voltage-stepping amplitude regulation in cases of large deviations in voltage at load. Phase channels of cycle converter control circuit are designed for alternation of stepping-up voltage in each phase separately in complete range of deviation of load voltage in phases. Voltage is stabilized by application of deviation signal of middle three-phase load voltage to rectifier control circuit and application of phase voltage deviation signal to cycle converter control circuit. Inverter control circuit provides possibility to increase mains frequency of output voltage of inverter as multiple to number of phases. EFFECT: improved power characteristics, decreased weight and size. 1 dwg
