Abstract: Aiming at the frequency instability caused by the low inertia characteristics of an electronic power system, this paper quantitatively analyzes the available energy of a MMC-HVDC system and its feasibility in actively supporting the system inertia from the perspective of exploring the regulation potential of the power grid transmission link. A self synchronization control strategy for the receiving end converter station that takes into account the capacitor energy margin is proposed, which achieves the self synchronization without the phase-locked loop and actively supports the inertia of the receiving end power grid. On this basis, considering the impact of the DC voltage safety constraints on the utilization of capacitor energy margin, a self synchronous decoupling control strategy and the parameter design method for adaptive inertia and damping simulation of MMC-HVDC systems are suggested. Through adaptively adjusting the inserted number of the sub-modules and the Moment of inertia, the capacity of the inertia support is further improved by using the capacitor energy margin. By introducing the damping control, the frequency deviation adjustment is achieved while improving the stability of the control system. The effectiveness of the proposed control strategy is verified through the real-time digital simulation.