Progress in high temperature superconductor coated conductors and their applications

TLDR

Second‑generation high‑temperature superconductor wires, based on coated conductor technology, have rapidly advanced, surpassing first‑generation wires in critical current density and mechanical performance, and are now displacing 1G wires in most applications. The study focuses on fault‑current limitation as an especially attractive application of 2G HTS wire. By adding a high‑resistivity stabilizer to the coated conductor, the wire achieves high resistance during a fault while providing heat capacity to limit temperature rise. The 2G HTS wires exhibit critical current densities and mechanical properties that match or exceed 1G wires, manufacturing is scaling to 10 km per year, and a 2.25 MVA fault‑current‑limiting system demonstrated by Siemens/AMSC confirms the technology’s commercial viability, with a novel cable approach also introduced.

Abstract

Second generation (2G) high temperature superconductor (HTS) wires are based on a coated conductor technology. They follow on from a first generation (1G) HTS wire consisting of a composite multifilamentary wire architecture. During the last couple of years, rapid progress has been made in the development of 2G HTS wire, which is now displacing 1G HTS wire for most if not all applications. The engineering critical current density of these wires matches or exceeds that of 1G wire, and the mechanical properties are also superior. Scale-up of manufacturing is proceeding rapidly, with several companies already supplying the order of 10 km annually for test and demonstration. Coils of increasing sophistication are being demonstrated. One especially attractive application, that relies on the specific properties of 2G HTS wire, is fault current limitation. By incorporating a high resistivity stabilizer in the coated conductor, one can achieve high resistance in a quenched state during a fault event and at the same time provide significant heat capacity to limit the temperature rise. A test of a 2.25 MVA single phase system at 7.5 kV employing such wire by the Siemens/AMSC team has demonstrated all the key features required for a cost-effective commercial system. A novel approach to providing fault current limiting functionality in HTS cables has also been introduced.