The invention relates to a power fluctuation and malfunction control system and method of a direct-current-transmission double-fed wind turbine set, and belongs to the field of wind power. The system includes a double-fed power generator, a stator-side converter, a rotor-side converter, a net-side direct-current converter and an energy storage system. According to the method, firstly, the energy storage system supplies power to the rotator-side converter to achieve inverse conversion; secondly, after a draught fan is enabled, the stator-side converter conducts rectification boosting, the net-side direct-current converter conducts constant power control and controls the energy storage system to charge and discharge electricity to achieve power fluctuation suppression; if voltage drop occurs to a power network, the net-side direct-current converter conducts constant direct voltage control, and the rotator-side converter and the energy storage system run in a voltage drop malfunction control mode; if overvoltage occurs to the power network, the energy storage system conducts voltage clamp on the power network; if the network is disconnected, the net-side direct-current converter conducts constant direct voltage control, the rotator-side converter makes the output power of the power generator turn to zero; and finally, the net-side direct-current converter is switched off. The power fluctuation and malfunction control system and method of the direct-current-transmission double-fed wind turbine set are conducive to usage of the double-fed wind turbine set in a flexible direct current transmission system.