Electric power transmission without loss: HTS superconducting cable

The paper contains an experimental model of a DC superconducting cable, designed and built in INCDIE ICPE-CA Bucharest. Designed in a pipe-in-pipe (PIP) structure, the superconducting wire is placed inside the inner pipe through which the cryogenic cooling agent circulates and the space between the pipes is evacuated (10-5 mbar). The internal structure of the superconducting wire consists of several identical HTS tapes, placed in parallel and maintained equidistantly by an insulating matrix. The conceptual model was numerically analysed in Comsol Multiphysics, highlighting the electromagnetic forces between bands and numerically evaluated to verify the structural choice validity. Made with YBCO high-temperature superconducting (HTS) tapes and cryogenically cooled with liquid nitrogen (77 K), the wires allow the transport of intense currents of 1,500 A DC with minimal losses. The scope of this research consists in analysing the functional aspects of the superconducting cable, making the conceptual model and highlighting the challenges for making cables with longer lengths and more intense currents (~ tens kA). Special attention was given to the evaluation of the thermal insulation of the cable in order to minimize losses and operating expenses due to the consumption of liquid nitrogen. This way, the main components of the heat transfer that affect the overall efficiency of the superconducting cable were identified and evaluated. The realization of the cable is also detailed, together with its associated characteristics.