Protection Requirements Capture for Superconducting Cables in TeDP Aircraft Using a Thermal-Electrical Cable Model

Abstract

Turbo-electric distributed propulsion (TeDP) for aircraft allows for the complete redesign of the airframe so that greater overall fuel burn and emissions benefits can be achieved. Whilst conventional electrical power systems may be used for smaller aircraft, large aircraft (~300 pax) are likely to require the use of superconducting electrical power systems to enable the required whole system power density and efficiency levels to be achieved. The TeDP concept requires an effective electrical fault management and protection system. However, the fault response of a superconducting TeDP power system and its components has not been well studied to date, limiting the effective capture of associated protection requirements. For example, with superconducting systems it is possible that a hotspot is formed on one of the components, such as a cable. This can result in one subsection, rather than all, of a cable quenching. The quench transition to normal conduction leads to a temperature rise which is not uniformly distributed along the cable length. Due to the high current density and low cable mass of a TeDP system, this damaging failure mode can occur over a short timescale. To improve the understanding of the formation of this failure mode and its impact on a TeDP distribution cable, this paper presents a transient thermal-electrical model based on numerical methods. Using this approach, the model is then used to provide new information supporting the capture of speed and sensitivity requirements for TeDP protection systems.