The BEST PATHS Project on MgB₂Superconducting Cables for Very High Power Transmission

Abstract

Abstract-BEST PATHS (acronym for "BEyond State-of-theart Technologies for rePowering Ac corridors and multiTerminal HVDC Systems") is a collaborative project within the FP7 framework of the European Commission that includes an MgB 2 -based power transmission line among its five constituent demonstrators. Led by Nexans and bringing together transmission operators, industry and research organizations, this demonstrator aims at validating the novel MgB 2 technology for very high power transfer (gigawatt range). The project foresees the development of a monopole cable system operating in helium gas in the range 5-10 kA/200-320 kV, corresponding to a transmitted power from 1 to 3.2 GW. The main research and demonstration activities that will be pursued over the four-year project duration are: 1) development and manufacturing of MgB 2 wires and of the cable conductor; 2) design and manufacturing of the HVDC electrical insulation of the cable; 3) optimization of the required cryogenic system; 4) electromagnetic field analysis; 5) design and construction of a prototype electrical feeding system including terminations and connectors; 6) testing of the demonstrator; 7) study of grid connection procedures and integration of a superconducting link into a transmission grid; and finally, 8) a socio-economic analysis of the MgB 2 power transmission system. CIGRÉ recommendations will be used to take into account the established international practices, and guidance will be given on newly addressed technical aspects. An overview of the project is presented in the paper, including the main tasks and challenges ahead, as well as the partners and their roles.

Performance of MgB2 Superconductor Developed for High-Efficiency Klystron Applications

“…A coil made with a 300-m long wire [4] and a coil with a 1.7-km long wire for MRI use [5] were successfully implemented. The use of MgB 2 is not limited to magnets; MgB 2 wires have been used as power cables in superconducting (SC) links at CERN [6] and in the Best Paths project [7].…”

Dendritic flux instability in MgB2films above liquid hydrogen temperature

“…

Magnetic flux instability limits potential applications of superconductors such as MgB2 in practical devices. Previous studies in MgB2 films exposed to magnetic fields revealed the occurrence of dendritic flux avalanches at temperatures below T~10 K. In the present work it is shown that films of MgB2 exposed to a fast-ramped magnetic field display a dendritic flux instability at elevated temperatures, up to 23 K. Such instability can therefore cause malfunctioning of practical devices based on MgB2 films even when operating at liquid hydrogen temperature.MgB2 is a promising material for superconducting applications such as electricity transmission cables, high-field magnets, energy storage devices, high power applications, and sensors [1][2][3]. Various characteristics ensure considerable attractiveness of this material, including its low cost, good mechanical properties, high critical current density, and relatively high critical temperature, Tc ~ 39 K. Nevertheless, dendritic flux avalanches resulting from the onset of a thermomagnetic instability in MgB2 [4][5][6][7][8], strongly challenges the use of this material in practical applications.

…”

Dichotomic Decision Optimization for the Design of HVDC Superconducting Links

“…Before proceeding, a brief summary of the Best Paths superconducting project is provided. The project focused on validating HVDC superconducting links operating at the multi-gigawatt level [ 13 ]. In a timeframe of four years (2014–2018), a full-size cable system demonstrator operating at 320 kV and 10 kA was specified, designed, optimized, manufactured, and successfully tested on industrial test platforms.…”

“…To avoid limitations and achieve an optimal design, dichotomic decisions are introduced, which can bring about a substantial change in the system configuration. We exemplify this approach through an in-depth description of the dichotomic decision-making process undertaken for the recently finished European project Best Paths [ 13 ], which demonstrated the first 3-gigawatt-class direct-current superconducting cable system [ 14 , 15 ].…”