Strengthening electric rail traction is a major lever for reducing greenhouse gas emissions in the transport sector. Although the basic design of electric traction substations has changed little over the past five decades, their components have steadily improved. To maintain this progress, the adoption of high temperature superconducting devices is a promising option, offering high current densities, compactness, and low electrical losses. Within the framework of the SuperRail project, this thesis investigates the feasibility of a superconducting DC traction substation.Four research directions were pursued. First, double racetrack REBCO superconducting coils were designed, manufactured, and characterized, showing robustness and suitability for transformer applications. Second, three prototypes of partially superconducting transformers were developed, combining a copper primary winding operating at room temperature with a REBCO secondary winding cooled by liquid nitrogen. The final prototype, rated at the kVA scale, demonstrated stable and reproducible performance. Third, this transformer was connected with a cryogenic diode rectifier and superconducting cables to form a kW scale superconducting DC traction substation prototype. Experimental tests confirmed the operational feasibility of the concept. Finally, a techno-economic analysis was conducted to determine the conditions under which a superconducting DC traction substation could become economically competitive with conventional technology.The main contributions of this thesis are: (i) the experimental development of partially superconducting transformers, (ii) the coupled operation of a superconducting transformer and a cryogenic rectifier, (iii) the first demonstration of the superconducting DC traction substation concept, and (iv) a life-cycle cost analysis incorporating technological uncertainties.