The modular multilevel converter (MMC) is a promising prospect as a high-capacity wind turbine converter, but it is necessary to address the issue of easy disconnection during low voltage faults in wind turbines. Thus a low voltage ride-through strategy based on supercapacitor energy storage is proposed. Considering the utilization efficiency of supercapacitors and the constraints of converters, the energy storage mode of supercapacitors is controlled through DC-DC converters, achieving power balance on the machine and network sides during faults and stabilizing the DC bus voltage. From the regulations of offshore wind farms, the active and reactive current distribution principles of a grid-side MMC during faults are determined. This can provide dynamic reactive power support to improve grid voltage. Simulation results show that the proposed strategy can effectively stabilize the DC bus voltage during grid faults, ensure the safe operation of MMC power devices, compensate reactive power to improve grid voltage, and enhance the fault ride-through capability and operational stability of large-capacity direct-drive wind turbine generators.