Capacitive energy storage system

The utility model discloses a capacitive energy storage system, which comprises at least one capacitor device, at least one converter device and a transformer device electrically connected with a medium-voltage bus, wherein the at least one capacitor device, the at least one converter device and the transformer device are electrically connected in sequence. The capacitor device comprises an energy storage unit used for storing electric energy and a capacitor management unit used for controlling the energy storage unit to output direct-current voltage when the steam turbine generator breaks down. The converter device comprises a DC/DC converter, a DC/AC inverter and a conversion control unit; the DC/DC converter is used for controlling stable output of DC voltage; the conversion control unit is used for controlling the DC/AC inverter to invert the DC voltage to an AC side according to the voltage information required by the medium-voltage AC bus to obtain an AC voltage consistent with the voltage information r