With the development of the subway network, the research on traction network faults is becoming increasingly important. To ensure the reliability of the subway network, better study the grounding point faults, obtain the subway short-circuit current close to the real one, and study the action characteristics of the high-voltage DC circuit breaker used in the subway under the fault current, a DC large current generating device is proposed, which can input the amplitude, frequency, initial phase angle, etc. of the waveform to generate the corresponding waveform. Considering the ripple effect generated by high-frequency switching, a virtual impedance control technology was designed with the inductance of the filter increased, in order to reduce the ripple size and ensure the lightweight design of the equipment. The experimental results demonstrate that this scheme effectively suppresses the ripple size and aligns with expectations.