The need for a technological breakthrough in high voltage power transmission lines for resilient and environmentally friendly urban grids, as well as for the transport of power over long distances from renewable energy sources to load centers, is an undeniable reality that needs to be addressed today. Of course, this is the case if we want to cope with the demand of electric power and massive electric vehicle use expected in the next few decades. SUPERFEM responds to this need by proposing a new set of novel metamaterials which brings together the outstanding electric characteristics of High Temperature Superconducting materials (HTS) with, the shielding magnetic properties of Soft Ferromagnetic layers (SFM), introducing them in the design of power conductors for HVDC and three-phase HVAC networks with nearly zero magnetic leakages and power losses. It is already known that although the HTS conductors offer unbeatable performance features for each one of these networks, their benefits are certainly true when single cables or isolated current-phases are considered, as the large inductive losses produced by any neighbouring cable can be neglected. However, as the electric utility industry for generation and end usage are almost exclusively AC, for three phase power systems or DC systems which will have to share the right of way with them, the reality is that the major factor contributing to the operational costs of HTS networks is the losses produced by the magnetic field created by each one of the other cables, a situation that can only be understood by the numerical modelling of these kind of applications, as the occurrence of hysteretic power losses needs to be calculated to the fore.
For the modelling of real power applications of HTS single- and three-phase power transmission lines, a conductor is more than just the HTS material, and in this sense two major types of insulation schemes for retrofitting underground power transmission lines with HTS conductors, the Warm dielectric (W-) and Cold dielectric (C-) designs will be considered, with the novel feature of adding HTS/SFM metastructures to reduce the hysteretic losses of the entire system. In a first stage, we will embed a multifilamentary HTS cable into SFM sheaths, such that the magnetization losses produced by the concomitant action of co-axial cables is reduced or, virtually eliminated, without the need of having further HTS shields which also serve as an additional source of power losses. Similar metastructures have been demonstrated to enhance the mechanical properties of HTS cables, but its electromagnetic behaviour for different superconducting and ferromagnetic composites and their overall performance under three-phase or DC multiconductor configurations is unknown. We aim to study different magnetic sheaths for HTS/SFM warm conductors into the actual commercial market of SFMs for power applications. In this sense, 33 different SFM materials with relative magnetic permeability ranging from ~1 to 35000 will be considered as part of this project, leading to the world's first map of AC-losses for single phase HTS/SFM transmission lines. This will be then extended to triaxial and triad designs of warm and cold dielectric transmission lines, finding the best route of investment for this technology with a significant cost reduction and efficiency gain as the primary targets.
The research proposed in this project is the first of its kind on the search of energy-efficient and resilient transmission networks, which in the long term aims to mitigate costs of grid reinforcement, replacement and upgrade of fault limiters and other power management devices, with greater levels of public acceptance and lowering of installation costs, due their reduced need for use of the right of way in highly populated areas.
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