Applications Of High Temperature Superconductors Research Articles

Processing and application of high-temperature superconducting coated conductors

Coated conductors formed from the high-temperature superconducting (HTS) material REBCO (REBa2Cu3O7−δ) enable energy-efficient and high-power-density delivery of electricity, making them key materials for clean energy generation, conversion, transmission and storage. Widespread application of HTS coated conductor wires requires operation at high temperatures in wide-ranging magnetic fields, as well as low-cost processing. In this Review, we investigate different processing methods and applications of HTS coated conductors, highlighting advances in laboratory-scale conductor processing and performance, and examining commercial potential. We discuss how the nanostructure of the HTS material impacts wire performance across different application regimes, and how the nanostructure and performance are related to the inherent supersaturation levels of the respective processing method. We outline approaches to decrease wire cost and improve wire performance in the critical application regime (20–40 K, >1 T magnetic field), and examine emerging and potential future applications of HTS coated conductors.

Design, Fabrication, and Testing of a Full-Scale HTS Coil for a 10 MW HTS Wind Power Generator

The authors have proposed a performance evaluation system (PES) for large-scale high temperature superconducting (HTS) wind power generators, which produces strong electromagnetic force and high torque due to the high excitation current and the high magnetic load of the machine, based on the computer simulation results. The PES can physically test the structural stability of HTS coils and armatures against high torque and the effect of the magnetic field before mounting the HTS coil on the generator. This paper deals with the design, fabrication, and performance testing of a full-scale HTS coil to be installed in the PES, a performance analysis system for a 10 MW HTS wind power generator. The HTS coil with metal-insulation consists of four racetrack-type single coils with 310 turns per layer. The manufactured HTS coil was tested at 77 K with and without an iron-core. As a result, the critical currents of the tested HTS coils with and without the iron-core were 90 A and 106 A, respectively. Compared to the simulation results, it was found that the magnitude of the magnetic field was the same. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated.

Обзор высокотемпературных сверхпроводниковых электрических машин

Electrical machines are important parts of different power systems. The application of high temperature superconductors (HTS) in electrical machines is very promising due to high transport currents. This paper reviews various topologies of superconducting motors and generators using HTS published in the literature in recent time. It begins with a brief presentation of the HTS material used in electrical machines. The description of AC losses and cryogenic systems is done afterwards. Then we offer a striking description of the various realizations of HTS electrical machines such as half HTS synchronous machines, fully HTS synchronous machine, machines with HTS bulks and stacks. Some of these machines are totally innovative compared to conventional ones and their operating principle is strictly related to the presence of HTS materials.

A Coupled A–H Formulation for Magneto-Thermal Transients in High-Temperature Superconducting Magnets

The application of high-temperature superconductors to accelerator magnets for future particle colliders is under study. Numerical methods are crucial for an accurate evaluation of the complex dynamical behavior of the magnets, especially concerning the magnetic field quality and thermal behavior. We present a coupled $\textbf{A}$-$\textbf{H}$ field formulation for the analysis of magneto-thermal transients in accelerator magnets. The magnetic field strength $\textbf{H}$ accounts for the eddy current problem in the source regions containing the superconducting domains, while the magnetic vector potential $\textbf{A}$ represents the magnetoquasistatic problem in the normal and non-conducting domains. Furthermore, we include a slab approximation for the source regions, making the formulation suitable for large scale models composed of thousands of tapes. In this work, the relevant equations are derived and discussed, with emphasis on the coupling conditions. The weak formulation is derived, and numerical results are provided in order to both, verify the formulation and scale it to the size of an accelerator magnet.

Applications of High Temperature Superconductors

Applications of High Temperature Superconductors

Comparison of fast computing methods for ZFC High-temperature superconductors bulks

With the development of high-temperature superconducting (HTS) materials, several HTS applications are been proposed and developed. Due to the HTS non-linear and non-homogeneous electromagnetic characteristics, the optimization process of an HTS system is a complex task requiring high computational time and resources. Within this context, this paper focuses on the comparison of HTS models for a fast estimation of the magnetization level of zero-field cooled HTS bulks. Four HTS models are analyzed: Kim’s model, Bean’s model, a simplified analytical model considering J = Jc and an equivalent permeability model. As a case study, these models are used to simulate the levitation forces of a horizontal axis HTS levitation system. A 3D Finite Element model is used as a base tool for the implementation of each model. Results are compared with the experimental ones. The simplified analytical model (J = Jc) and the equivalent permeability model present accurate enough results with a very low computational time when compared with Kim’s and Bean’s models. For the 3D simulation of the levitation system, a computational time between 10 and 24 h is required for the Kim’s and Bean’s models, while only between 10 and 30 s for the simplified analytical and equivalent permeability models. Besides, the simplified analytical model (J = Jc) also provides information about the eddy-current losses inside the HTS bulks.

Development of a Half-Size 3 T REBCO Superconducting Magnet for MRI

We have been developing a liquid-helium-free 3T magnet for MRI using high-temperature superconducting (HTS) wires in a HTS application project supported by the New Energy and Industrial Technology Development Organization (NEDO). A half-size 3T-MRI magnet, which has 220 coils each of order meter size, has been manufactured in order to demonstrate MR imaging. 269 REBCO single-pancake coils were manufactured. We investigated the yield rate of meter-class REBCO coils by experiment and the degraded state of coils by calculation. It was found that the yield rate was 82 % and the degraded length was order millimeter size in total length of coil, which was several hundred meters. We will consider the factors of coil degradation and how to increase the yield rate of a REBCO coil.

Performance Study on the No-Insulation HTS Coil Wound With Narrow-Stacked Wire

As a novel high-temperature superconducting (HTS) conductor structure composed of the stacked 1-mm wide REBCO tapes, Narrow-Stacked (NS) wire has been demonstrated to have a significant reduction effect of AC loss and screening current induced field (SCIF) in the insulated HTS coils. Thus, NS wire is a promising HTS conductor design for practical HTS applications. Meanwhile, compared with traditional insulated HTS coil, no-insulation (NI) HTS coil has obvious advantages in engineering current density, thermal stability and self-protecting ability, and these features benefit for HTS magnets. Although NS wire was regarded as an improvement for insulated HTS coil, the NS wire effects on NI coil are not confirmed yet due to the special characteristics of the NI coil. In this paper, NI pancake coils were wound with NS wire and conventional HTS tape respectively. To evaluate the performance of NI coil wound with NS wire, its characteristic resistance and charging delay were analyzed at the liquid nitrogen temperature of 77 K. Besides, the over-current test results show that NI NS coil also has the satisfied self-protecting feature. This paper intends to provide a possible reference for NS wire application on NI HTS magnets.

High permittivity and low dielectric loss of (1-x) Bi0.5(Na0.48K0.52)0.5TiO3-xBaZrO3 lead-free ceramics

Herein, (1-x)Bi0.5(Na0.48K0.52)0.5TiO3-xBaZrO3 ceramics (aliased as (1-x)BNKT-xBZ, where x = 0.00, 0.03, 0.06, 0.09) were fabricated via solid-state reaction, and the microstructure, dielectric as well as impedance properties were researched in detail. It was found that all the samples exhibited a perovskite structure and few other secondary phase was monitored. With the increase of doped BZ, the mean grain size became lager. Compared with the pure BNT ceramic, the introduction of BZ could effectively optimize the performance of (1-x)BNKT-xBZ ceramics. The dielectric constant could reach 4624, and dielectric loss was as low as 0.0028. Using a modified Curie–Weiss law, the Curie constant, the maximum temperature (Tm), and the diffuseness’ degree were systematically investigated. The behavior of the negative temperature coefficient for this ceramic is observed by impedance spectroscopy, which is similar to that of a semiconductor. Hence, our results indicate that the ceramic can be a promising candidate for high-temperature superconductor applications.

Study on Different YBCO Bulk Arrangements With a Fan-Shaped Electromagnetic Guideway of HTS Maglev

The application of High Temperature Superconducting (HTS) technology in the maglev field has met a giant improvement in the recent years. With the success in the laboratorial test lines, the scientists started to focus on the research of practical issues on reality applications. Lately, our team devoted ourselves into the study of Electromagnetic Guideway (EMG) for improve the flexibility and the practicability of guideway in an HTS maglev system. In this paper, a fan-shaped EMG was proposed, its basic unit was analyzed through magnetic equivalent circuit method, in order to decide the rated magnetomotive force. Afterward, a prototype was made to verify the design feasibility, the comparison among three arrangements of HTS bulks were carried out with the experiments under different measuring conditions. The levitation and guidance performances of each arrangement were comprehensively discussed as the summary.

Overview of H-Formulation: A Versatile Tool for Modeling Electromagnetics in High-Temperature Superconductor Applications

This paper reviews the modeling of high-temperature superconductors (HTS) using the finiteelement method (FEM) based on the H-formulation of Maxwell's equations. This formulation has become the most popular numerical modeling method for simulating the electromagnetic behavior of HTS, especially thanks to the easiness of implementation in the commercial finite-element program COMSOL Multiphysics. Numerous studies prove that the H-formulation is able to simulate a wide scope of HTS topologies, from simple geometries such as HTS tapes and coils, to more complex HTS devices, up to large superconducting magnets. In this paper, we review the basics of the H-formulation, its evolution from 2D to 3D, its application for calculating critical currents and AC losses as well as magnetization of HTS bulks and tape stacks. We also review the use of the H-formulation for large-scale HTS applications, its use to solve multi-physics problems involving electromagnetic-thermal and electromagnetic-mechanical couplings, and its application to study the dynamic resistance of superconductors and flux pumps.

Production and Characterization of Strands for a 35 kA HTS DC Cable Demonstrator

Over the past years, high temperature superconductors (HTS) Direct Current (DC) power distribution has received increased attention. One particular scenario is the application of HTS in energy-intensive industries to substitute conventional copper or aluminum bus bar systems. The use of HTS in these scenarios creates significant benefits regarding space, weight, and system losses. In industrial electrolysis, currents of up to several hundred kiloamperes are commonly encountered. One way toward a HTS cable with such high currents is to assemble multiple high current HTS strands into a cable. The HTS CroCo, developed at KIT, can serve as a high current strand for such cables. This paper reports on the progress in HTS CroCo manufacturing as well as the results of the CroCo characterization. With a new manufacturing machine, 8-m-long HTS CroCos within a round solder matrix were produced and cut into pieces, each 3.6 m in length. Twelve HTS CroCo pieces were characterized at 77 K, self-field. The tested HTS CroCos will be assembled to a HTS dc cable demonstrator that is designed to have a critical current of 35 kA at 77 K in self-field. To allow an individual measurement of the different HTS CroCos within the cable assembly, the strands will be connected in a first step individually to the feeding bus bar. The impact of the lead resistance and critical current distribution of the individual HTS CroCos on the current distribution within the assembled 35 kA cable demonstrator is discussed.

High Temperature Superconductor-Based Technologies as Enabler for Efficient and Resilient Energy Systems

New technologies based on the use of High Temperature Superconductors (HTS) can lead to higher efficiency and more resilient energy systems. HTS applications are creating unique opportunities for promising commercial components that can enable the needed evolution of the energy system, such as high-capacity power cables, fault current limiters, high-efficiency generators for offshore wind turbines, energy storage, and innovative transformers. Not only do superconductor-based devices provide improvements over conventional electric grid technologies, they also offer unique alternatives to system challenges that cannot be addressed otherwise. This paper, developed by the International Energy Agency's Technology Collaborative Program on High Temperature Superconductivity, will explore the potential capabilities of HTS-based devices to advance the transformation of today's energy systems toward more a reliable, resilient, secure, affordable, flexible, and efficient regime.

Comparison of Heat Assisted Lap Joints of High-Temperature Superconducting Tapes With Inserted Indium Foils

Easy and simple fabrication of a lap joint of high-temperature superconducting (HTS) tapes is desirable for various HTS applications such as power cables and current feeders. We have developed mechanical joints with a low-temperature heat treatment at around 370 K where indium foils are inserted between joint surfaces. Though the joint showed a good performance, it took over 10 min to fabricate one joint and ideally the fabrication time should be further shortened. In this study, we proposed to use ultrasonic welding (UW) to assist a heat generation at the joint for lap joints with indium foil, which can be completed within 1 s. We prepared various lap joint samples of HTS tapes: REBCO (REBa 2 Cu 3 O 7 , RE: rare-earth) or BSCCO (Bi 2 Sr 2 Ca 2 Cu 3 O 10 ) tapes were pressed together with an indium foil using a UW machine or pressing machine with cartridge heaters. Then, the current-voltage curve was evaluated at 77 K and the joint resistance characteristics were discussed depending on the joint methods and HTS tapes. The samples with copper-stabilized REBCO tapes all showed joint resistivities of 31.6-35.6 nΩcm 2 without critical current (I C ) degradation for both joint methods. The samples with silver-sheathed BSCCO tapes showed joint resistivities of 18.6-46.5 nΩcm 2 for both joint methods; however, some of those fabricated by the UW showed I C degradation. The degradation was able to be prevented by optimizing UW conditions.

Study of the heat transfer capacity of thermosyphon cooling system under the inclined condition

Machine applications with superconductors attract much interest in the industry. It is crucial to maintaining the operating temperature range between 28 K and 40 K for high-temperature superconductor (HTS) field poles. A thermosyphon (TS) is a suitable choice for HTS applications’ cooling system. The cryo-mechanical system composition is simple, lightweight and based on natural convection therefore not using any mechanical pump. Considering the rotating application, an adiabatic tube is necessary to carry the cryogen from the vertical condenser portion toward the horizontal evaporator part. However, this tube shape prevents the natural convection when in an inclined configuration which can occur for applications such as ship propulsion and electrical aircraft motors or generators. In this work, we focused on and investigated the heat transfer capacity of TS for inclinations. The results show that the TS cooling system employing the coaxial tubes architecture maintained the natural convection even under inclined conditions

Design and Experimental Study of the Wireless Online Monitoring System of a High-Temperature Superconducting Machine

As an important research topic of ship electric propulsion and new power generation, high-temperature superconducting (HTS) machines have become a research hotspot in the field of HTS applications in recent years. With high power density, high efficiency, and outstanding dynamic characteristics, HTS motors could bring much more great social and economic benefits. Meanwhile, the application conditions of HTS materials are harsh, and any parameters of the HTS materials beyond the safe range of operation are probable to lead the HTS materials to quench. The quenching of HTS materials changes the state parameters of power devices; what's more, it will bring a huge impact on the safety and stability of HTS power system. To ensure the safe operation of the HTS machine, by detecting the voltage, environment temperature, and liquid nitrogen level, this paper designed a wireless online monitoring system to determine whether the HTS material has failed. The system is based on the brief principle of superconductor quench. In addition, the system was applied to a 500-kW HTS power generator. The experiment shows the sufficient accuracy and reliability of the wireless online monitoring system.

Measurement of the Current in 2G HTS Coil With Rogowski Coil in Cryogenic Environment

This paper presents a Rogowski coil that can be used to measure the current in second-generation (2G) high-temperature superconducting (HTS) coils in a cryogenic environments. We describe the key materials involved in building the coil and its structure and then report on experiments that were carried out to assess its potential. To ensure the accuracy of current measurements in cryogenic temperatures, the coil was given a closed and rigid shape and foamed plastic was used to fix a 2G HTS wire in the center of the coil. Silicon nitride ceramic was chosen to build the winding holder because of its thermodynamic stability and mechanical strength in cryogenic environments. The performance of the Rogowski coil was evaluated in a liquid nitrogen bath at 77 K. The results confirmed the stability of the coil and the accuracy of its current measurements, underscoring its viability for 2G HTS applications.

AC Loss Analysis of High-Temperature Superconducting Current Leads With Nonsinusoidal Current Waveform

For some high-temperature superconducting (HTS) devices, such as fusion magnet, fault current limiters (FCLs), and superconducting energy magnetic system, the ac loss of the HTS current leads is one of the most important heat sources in the cryogenic system. When HTS current lead is carrying alternating current, ac loss occurs. However, the HTS current leads of the above HTS devices usually carry the nonsinusoidal current, and the ac loss is difficult to be analyzed when the applied transport current is nonsinusoidal waveform. In this paper, we firstly proposed two kinds of structure of HTS current leads, and the ac losses of these two current leads with the specific current waveform were calculated subsequently by using finite element method software COMSOL. Furthermore, the ac losses of two structure current leads were measured by using the integral method, respectively. Finally, the ac loss results of these two structures of current leads were compared and analyzed theoretically and experimentally, which aims to select the preferred structure of current lead for HTS applications in terms of ac loss.

Effects of Mechanical Force on Critical Current of Soldered-Stacked-Square (3S) HTS Wires

Narrowing high-temperature superconducting (HTS) tapes can effectively enhance the ability of antielectromagnetic interference. In addition, different structures of HTS wires are necessary for HTS applications. Thereby, a kind of soldered-stacked-square (3S) HTS Wires has been proposed. This paper presents a process of fabricating several 3S HTS wires. A normal second-generation (2G) HTS tape having 4-mm width was narrowed into four 1-mm-width narrow HTS tapes. The main propose of this paper is to study different effects of mechanical force on the critical current of 3S HTS wires. Therefore, we measured the critical current variation of these wires from the torsion, bending, and tension effects points of view, respectively. Compared with their initial critical current values, if the reduction of the influenced critical current is smaller than 5%, it can be considered that these 3S HTS wires are workable. Based on the results of the experiment, the limitations of mechanical force for these wire applications are: minimal twisting pitch of 64 mm, minimal bending diameter of 54 mm, and maximum tensile force of 374 N.

Superconducting technologies for renewable energy

The main trends in the development of modern wind-mills are increasing of the output power and efficiency which leds to the increasing of their weight and sizes. The application of high temperature superconducting (HTS) technologies can solve these problems. The article describes of the designs 1 MVA superconducting synchronous generator and 5MJ flywheel energy storage systems (FESS) with HTS magnetic suspension for autonomous wind power engineering.