The VSC-HVDC grid has characteristics of fast rising rate and high peak value of DC fault current. At present

the immaturity of fault current suppression technology hampers the development and construction of the VSC-HVDC grid. Many researches use the DC current limiter or improve the converter topology to decrease the fault current. However

the above schemes also suffer from the additional investment of the DC grid. This paper proposed an adaptive-current-limiting control scheme of the half-bridge modular multilevel converter（MMC）. This scheme could effectively reduce the fault current of the DC grid

without adding any equipment. The principle of the current-limiting control

together with the structure of the controller

were firstly introduced. The calculating equations of DC current and arm currents of the half-bridge MMC were derived. The calculating equations of fault currents under current-limiting control were further derived and verified. Eventually

the four-terminal DC grid based on half-bridge MMC was simulated to verify the effectiveness of the current-limiting control. The simulation results shown that the proposed current-limiting control could not only reduce breaking current and absorbed energy of the DC circuit breaker（DCCB） by 4.29 k A（40.74%） and 23.4 MJ（60.47%）

respectively

but also could decrease the peak arm currents and the risk of converter block.