Energy storage unit, MMC, DC power transmission system and short-circuit current control method

The invention discloses an energy storage unit, an MMC, a DC power transmission system and a short-circuit current control method, and relates to the technical field of power system stability analysis, and the technical scheme is characterized in that a control mode, a current limiting mode and a power reference value of the MMC in the DC power transmission system are set; starting a direct-current power transmission system; when the alternating current system operates normally, an energy storage unit of the MMC in the direct current power transmission system is charged; and when a three-phase short-circuit fault of the AC system is detected, a control strategy is rapidly optimized, and a current limiting mode of the MMC inner loop current controller is modified into a reactive power priority mode. And meanwhile, an insulated gate bipolar transistor of the energy storage unit is triggered and conducted, so that the energy storage unit discharges until the fault is recovered or the discharge of the energy stor