Abstract: Flexible DC grids have the characteristics of "low inertia and weak damping", and their fault current rises rapidly with high peak value. Current limiting devices usually contain a huge number of power electronic devices, which not only increases the complexity of the system, but also reduces the simulation efficiency of the DC grids. An equivalent modeling method is proposed for different current limiting devices, so as to improve the simulation efficiency of the model and meet the requirements of system design and operation analysis. Firstly, a digital simulation model of a 17-terminal flexible DC grid with various current limiting devices is built in this paper. Then, according to the generalized equivalent modeling method for single-port sub-module, an effective equivalent modeling strategy is proposed for four typical fault current limiting devices respectively. Finally, the digital model of 17-terminal DC grid is processed in real-time based on RT-LAB platform to complete the construction of the real-time model. The simulation results show that the proposed equivalent method and the real-time simulation model can accurately fit various working conditions such as steady-state and fault.