Abstarct: HTS DC cables, due to their very low losses and high current capacity, have received special attention, especially in long transmission lines. However, to better utilize these cables in power systems, it is necessary to evaluate their performance under steady-state and transient conditions. Achieving this requires a model with the most details and adjustable parameters of the HTS DC cable, so that the electrothermal and magnetic behavior of these cables can be analyzed under transient network conditions and in various power system configurations. In this research, a Self-Shielding HTS DC cable with a multilxayer structure and a voltage level of 1 kV has been designed using the equivalent electrical circuit method. The simulated model allows for the electrothermal and electromagnetic analysis of the cable under steady-state and transient network conditions. By considering the physical parameters of the cable, such as the number of tapes in each laxyer, pitch, angle and direction of twisting, and the direction of current flow through the laxyers, structural and mechanical changes of the cable can also be analyzed and evaluated. Another advantage of the circuit model is that the cable model can be used in any power system topology and those networks can be analyzed in the presence of the HTS DC cable. Given the presented model for the multilxayer HTS DC cable, the model can be generalized for any number of laxyers and tapes to achieve the required current capacity. Considering the AC ripple effect in the output currents of AC/DC converters is another parameter considered in this thesis. For the study of the transient period and thereafter, pole-to-pole and pole-to-ground faults with different fault resistances have been considered. Parameters such as current, temperature, losses, and resistance in different laxyers during the fault occurrence and cable recovery period have been modeled to evaluate the performance of the modeled HTS DC cable.