HVDC transmission technology is one of the main ways to realize bidirectional control of active power, avoid commutation failure and achieve wind power integration. However, HVDC wind power integration systems are prone to AC&DC faults. As the wind turbines continuously output power during the fault, the transient surplus energy endangers the safe operation of the system. Given this transient energy dissipation problem of an HVDC wind power integration system, this paper proposes a full-bridge sub-module-based flexible energy dissipation device (FEDD). To accurately control the charging and discharging of the sub-module, a dynamic voltage control strategy and transient energy dissipation strategy are proposed, and the capacitance energy balance of the sub-module is taken into account. In addition, based on the working principle and control strategy of the FEDD, the design methods of its main parameters are proposed. Finally, the RTDS simulation results verify that the FEDD can realize transient energy dissipation of the HVDC wind power integration system and ensure the converter stations smoothly ride-through AC and DC faults. This work is supported by the National Key Research and Development Program of China (No. 2016YFB0400405).