Flexible reserve capacity support is important for mitigating active power imbalance issues in asynchronous power systems. Electrolytic aluminum loads (EALs), owing to their large capacity and rapid response, are used as regulation resources in this study. Combining EALs with renewable energy generation units allows the sending power system to provide active power support to the receiving power system when a large power disturbance occurs. An active power support control strategy is proposed for a voltage source converter based high voltage direct current (VSC-HVDC) asynchronous power system. The active power control method of the EAL is analyzed as the foundation, and the load frequency control models of the sending and receiving systems are presented to promote the proposed control strategy. Active power controllers based on model pre-dictive control (MPC) theory are designed to manage power system uncertainties and external disturbances. The proposed active power support control strategy is realized by optimizing the regulation resources in the sending power system while maintaining a stable frequency when the reserve capacity of the receiving system is insufficient. An actual industrial power grid with renewable energy is selected as the sending system and simulations are performed to verify the effectiveness of the proposed active power support control strategy and MPC-based controllers.