The DC direct-mounted supercapacitor energy storage system (DCDM-SESS) is a kind of grid-supporting equipment with good application prospects

featuring large unit capacity

high energy utilization efficiency

and flexible power configuration. However

the existing grid-forming control techniques do not hold for the DCDM-SESS. Firstly

the virtual synchronous machine control strategies suffer from the inherent shortcomings of uncontrolled supercapacitor energy and a mismatch between system stability requirements and supercapacitor capability. Secondly

although matching control can solve the problem

the existing damping enhancement strategies fail or suffer from shortcomings such as complex parameter tuning. Last but not least

the existing current limitation strategies under the grid-forming control framework are generally premised on the same active and reactive capacities and therefore cannot accommodate the differentiated power design characteristics of the DCDM-SESS. To this end

an improved matching control strategy based on supercapacitor energy self-synchronization and active power feedback to enhance damping is proposed in this paper

which can realize the organic combination of phase-locked-loop-free grid self-synchronization with oscillation suppression over full power range

spontaneous inertia response and supercapacitor energy autonomous management. In addition

a dual current and power-limiting technique is presented to ensure the safety of both power transistors and supercapacitors. These methods are validated by PSCAD/EMTDC simulations and hardware-in-the-loop experiments.