Superconducting Cable Research Articles

Decarbonizing the electricity sector using terawatt-scale interconnected photovoltaic power grids to meet the climate goals: A comprehensive review and a strategic roadmap

High scalability and quick deployability of solar photovoltaic (PV) make it an ideal candidate for rapid decarbonization of electricity. The typical SPV generation profile and power grids designed for conventional power plants (PP) are the major obstacles to maximizing SPV utilization. While energy storage systems (ESS) are often deemed critical, scalable ESS are site-limited, highly dependent on rare-earth elements, and either have higher embodied energy and emissions or low round-trip efficiencies. This manuscript demonstrates that by strategically interconnecting SPV power plants longitudinally, PV can meet base load demands and extend availability beyond peak-solar hours, thereby reducing the need for ESS and replacing existing carbon-intensive electricity infrastructure. It is demonstrated by modelling two 12 GW longitudinally separated transmission lines interconnecting SPVPPs situated 40° (case-1) and 90° (case-2) apart can provide PV electricity beyond solar hours for 4.69 and 7.33 equivalent hours (daily average), respectively. For cases 1 and 2, the lithium battery-ESS route can result in 4.76 and 3.35 times more carbon emissions and cost 4.23 and 2.98 times more than the transmission route, respectively, for providing the same energy over the transmission line's 40-year lifespan. Technologies such as multi-terminal ultra-high-voltage-DC grids, hybrid superconductive cables, new semiconductor materials for PV and energy systems, etc. are explored for the globally interconnected solar grid. Findings suggest 90 TWp of PV capacity can supply a significant portion of world's energy demand by 2050. This study outlines a comprehensive approach to build a sustainable and interconnected global solar energy infrastructure that aligns with climate objectives.

Performance enhancements of HTS power cables by minimizing the electric field enhancements for electric transport applications

Abstract Design innovations to manage the electric field enhancements and successful use of cryogenic epoxy EP37 as electrical insulation for high temperature superconducting (HTS) cables for electric aircraft applications are reported. Detailed finite element analysis (FEA) of the electric field distribution shows that the highest electric field is at the interface of the ground and electrical insulation layers. The FEA led to the design, fabrication, and experimental characterization of four model cables with stress cones and a direct bond of the ground and insulation layers. Enhanced partial discharge inception voltage (PDIV) was achieved in the model cables by minimizing the electric field enhancements at the ground layer interface. Using a helium gas mixture with 4 mol% H2, with higher intrinsic dielectric strength than pure helium, further enhanced the PDIV. The results warrant further studies on long HTS cables with EP37 as electrical insulation with a direct bond between the insulation and ground layers.

Quench protection for high-temperature superconductor cables using active control of current distribution

Superconducting magnets of future fusion reactors are expected to rely on composite high-temperature superconductor (HTS) cable conductors. In presently used HTS cables, current sharing between components is limited due to poorly defined contact resistances between superconducting tapes or by design. The interplay between contact and termination resistances is the defining factor for power dissipation in these cables and ultimately defines their safe operational margins. However, the current distribution between components along the composite conductor and inside its terminations is a priori unknown, and presently, no means are available to actively tune current flow distribution in real-time to improve margins of quench protection. Also, the lack of ability to electrically probe individual components makes it impossible to identify conductor damage locations within the cable. In this work, we address both problems by introducing active current control of current distribution between components using cryogenically operated metal-oxide-semiconductor-field-effect transistors (MOSFETs). We demonstrate through simulation and experiments how real-time current controls can help to drastically reduce heat dissipation in a developing hot spot in a two-conductor model system and help identify critical current degradation of individual cable components. Prospects of other potential uses of MOSFET devices for improved voltage detection, AC loss-driven active quench protection, and remnant magnetization reduction in HTS magnets are also discussed.

Intelligent surrogate model of a high-temperature superconducting cable for reliable energy delivery: short-circuit fault performance

High-temperature superconducting (HTS) cables are promising solutions for electric power transmission of renewable energy resources, where their fault performance study is vital to avoid power interruptions in the grid. In this study, a fast intelligent surrogate model was presented to estimate the fault performance of a 22.9 kV/50 MW HTS cable to make fast fault performance analysis of the HTS cables possible during the design stage. Different fault scenarios were considered under different fault durations, fault resistances, and types of faults. Then, the fault energy, fault current, fault type, fault duration, and fault resistance were fed into the surrogate model as inputs. The outputs were the temperature of the rare-earth barium copper oxide (ReBCO) tapes, the former temperature, the ReBCO layer current, and the total resistance of each phase. For surrogate modelling, cascade forward neural networks (CFNNs) were used. The results show that the CFNN-based model estimated the fault performance of the cable with an average accuracy of 99.1%. Finally, the impact of considering fault energy, fault current, and both, as the inputs of the models, on the final accuracy were explored. The results show that by considering the fault energy, the accuracy of the surrogate model can be increased.

A platform to study defect-induced behavior in high-temperature superconductor cables

High-temperature superconductor (HTS) cables and magnets are enabling a range of high-current and high-field applications, including compact fusion devices aiming to achieve net energy. Defects in HTS pose manufacturing, cost, and operational challenges. A rigorous understanding and predictive capability for defect-induced behavior at relevant scale has not been established. To address this shortcoming, we have developed a cable-level defect characterization experimental platform coupled to high-fidelity computational modeling. The cable ( Ic∼ 438 A at 77.4 K, self-field) comprises a non-twisted 70 cm-long copper former containing a soldered stack of five rare-earth barium copper oxide (REBCO) tapes (each with Ic = 115.7 A/4 mm-w at 77.4 K, self-field), which can contain a variety of induced defects. Spatially-resolved electric fields are measured with a high-density voltage tap array and absolute current distribution with six custom-wound embedded Rogowski coils. 3D circuit modeling uses nodal analysis and self-consistently accounts for the magnetic field dependence of critical current. The model successfully predicts the experimentally measured spatial and operating current dependencies of electric field and current distribution with no defects, one defect, and two defects, validating the defect characterization platform as a tool for improving the design, cost, fabrication, and operation of REBCO cables.

Applying High-Temperature SuperconducTechnologies into Power Systems

implementing of distribution and transmission power systems for urban areas and for future renewableenergy to meet future demand is a challenging task whenconventional cables and transformers are considered.Therefore, there are several methods, that have applied inconational power systems to reduce power losses, voltage regulator issues , capital cost of whole system and increasingpower delivering in urban areas and from offshore farms,such as carefully sited and operated distributed generation(DG) and distributed control techniques. However, thesetechniques may raise others challenges in networks such as stability, voltage regulators issues and increasing capital costof networks. Since High Temperature Superconductor(HTS) cables exhibit zero resistance when cooled to theboiling point of liquid nitrogen (77Keliven), they have thepotential to be used to address these issues in distribution and transmission networks. Consequently, this paperreviews super-conductor power systems: the workpreviously achieved in the DC and AC superconductorpower systems and describes the materials and methodswhich they used. In addition, it shows how the superconductor technologies can address these issues whenthey are used for distribution and transmission powe r systems.

Current sharing in double-sided REBCO tapes

Current sharing between RE–Ba–Cu–O (REBCO, RE = rare earth) tapes within a high-temperature superconducting coil or cable is important to avoid damage from uncontrolled quench of superconducting devices operating at high currents. Current sharing between REBCO tapes is found to be limited by the contact resistivity between adjacent tapes, which is about 20x higher in the REBCO-facing-substrate (face-to-back) configuration that is commonly used in devices compared to a REBCO-facing-REBCO (face-to-face) configuration. Double-sided REBCO tapes always offer face-to-face contacts between adjacent tapes, and this benefit of excellent current sharing has been validated in experiments wherein an artificial defect is introduced in one tape in a 2-ply tape stack. Additionally, current sharing between the two REBCO layers within one double-sided REBCO tape has also been investigated. Slotting of the double-sided tapes, wherein slots through the insulating buffer stack are filled with a conductive material, has been found to significantly enhance the current sharing from one REBCO layer to the opposite layer.

Cryogenic and safety design of the future high field cable test facility at Fermilab

The HFVMTF (High Field Vertical Magnet Test Facility) is a new experimental facility under development at Fermi National Accelerator Laboratory (FNAL) to test large superconducting magnets (up to 20 tons weight and 1.3 m diameter) in a double bath superfluid helium cryostat (1.9 K and 1.2 bar). Coupled with a superconducting dipole magnet fabricated by Lawrence Berkeley National Laboratory (LBNL), this facility will be able to test future high-temperature superconductor (HTS) cables under a background magnetic field of 15 T for fusion magnets. This paper describes the design of the cryostat and its 1.4-meter diameter lambda plate, as well as the different components for a safe operation of the facility, even during critical events such a magnet quench or a vacuum breaking situation. The project is funded by US DOE Offices of Science, High Energy Physics (HEP), and Fusion Energy Sciences (FES).

Development of Joint Technology on Superconducting Cables for Feeder

Development of Joint Technology on Superconducting Cables for Feeder

Multi-Sensor Quench Detection System for an HTS Slotted Superconducting Cable

Multi-Sensor Quench Detection System for an HTS Slotted Superconducting Cable

Development of a Superconducting Cable for Aircraft Electric Propulsion System

Development of a Superconducting Cable for Aircraft Electric Propulsion System

Feasibility of high temperature superconducting cables for energy harvesting in large space-based solar power satellite applications: Electromagnetic, thermal and cost considerations

The aim of this paper is to present feasibility of application of High Temperature Superconducting (HTS) cables for Space-Based Solar Power (SBSP) application. SBSP is a promising technology that can deliver an infinite amount of clean and eco-friendly energy to the Earth. To deliver the harvested solar energy to the power systems on Earth, efficient energy transmission is critically important. To address the challenges of conventional transmission means, an ideal solution would be using HTS cables. In this research, the design procedure of a Direct Current (DC) HTS cable considering electromagnetic, thermal, and cost constraints is presented. The study considered a 2 MW bipolar DC HTS cable in five operational temperatures: 20 K, 30 K, 50 K, 65 K, and 77 K. The results were showed that the cost and weight of the designed HTS cables were increased by operational temperature increase. However, the cooling cost of HTS cable in higher temperatures, was less than lower temperatures. Also, the total efficiency of the HTS cable and cooling system were increased, when operational temperatures were changed from 20 K to 77 K, from 99.70% to 99.97%, respectively.

Alternative analytical models for HTS tapes considering their AC hysteretic and resistive losses

This work proposes two alternative analytical models to evaluate the ac losses of high-temperature superconducting (HTS) tapes during their hysteretic and resistive modes. These models intend to extend the application range of state-of-the-art analytical models for current values higher than the critical one, i.e. for the resistive state, and to correctly predict the ac losses during the transition between the hysteretic and resistive modes. Two analytical models are proposed, one considering an extension of the Norris model for the HTS tape’s resistive mode and the other based on a sigmoid function to characterize the hysteretic losses and their smooth transition to the resistive mode. Analytical models capable of estimating ac losses of superconducting (SC) tapes are an important tool for the design of complex SC systems, such as SC fault current limiters, SC electrical machines and SC cables. The proposed models are validated experimentally, for a 1st generation BSCCO tape and a 2nd generation REBCO tape. Finite element simulation is also carried out to verify the accuracy of the proposed models. Results show that the proposed extended-Norris model presents some deviation at the transition between the hysteretic and resistive modes, while the sigmoid model presents very accurate results for the whole spectrum of applied current. Also, the parameters of the sigmoid models are independent of the tape geometry.

Cryogenic Energy Supply of Liquid Nitrogen and Superconducting Cable for Supercomputer Energy Security and Service Continuity

Cryogenic Energy Supply of Liquid Nitrogen and Superconducting Cable for Supercomputer Energy Security and Service Continuity

The Latest Progress in China's High-Temperature Superconducting Cable Industry

The Latest Progress in China's High-Temperature Superconducting Cable Industry

Transient research on distribution networks incorporating superconducting cables utilizing field–circuit coupling method

High temperature superconducting (HTS) cable represents a promising solution for fulfilling the power demands of cities with large loads and high density. However, due to their connection to the distribution network, HTS cables are vulnerable to fault currents exceeding ten times their rated current, which poses a serious threat to both the safety of the cable and the operation of the grid. Considering the highly nonlinear nature of superconducting conductivity, this study develops a field–circuit coupling model to investigate the transient characteristics of distribution networks incorporating superconducting cables (DNSC). Firstly, a finite element model based on the two-dimensional H formulation was built to calculate the electrical and thermal parameters of the HTS cable. Subsequently, an equivalent circuit model of the distribution network was employed to estimate the short-circuit currents. Communicating via a co-simulation server, the superconducting cable current and distribution network impedance were updated in each step. Further, based on an actual DNSC system in Shenzhen, China, the highest quenching temperature of the cable and the maximum fault current of busbars were assessed. Finally, by integrating current limiters into the system, the withstand capability of the cable and busbars was determined, which indicates that the improved protection configuration can effectively suppress fault currents and ensure safe operation. Successfully applied to an actual distribution network, the co-simulation model utilizing the field–circuit coupling method addresses the challenges of solving highly nonlinear and time-varying systems, enabling transient analysis and protection research for the integration of superconducting devices into the conventional grid.

BELFEM: a special purpose finite element code for the magnetodynamic modeling of high-temperature superconducting tapes

Predicting the performance and reliability of high-temperature superconducting (HTS) cables and magnets is a critical component of their research and development process. Novel mixed finite element formulations, particularly the h -φ-formulation with thin-shell simplification, present promising opportunities for more efficient simulations of larger geometries. To make these new methods accessible in a flexible tool, we are developing the Berkeley Lab Finite Element Framework (BELFEM). This paper provides an overview of the relevant formulations, discusses the current state of the art, and discusses the main aspects of the BELFEM code structure. We validate a first 2D thin-shell implementation in BELFEM against selected benchmarks computed in COMSOL Multiphysics and compare the performance of our code with a comparable formulation in GetDP. We also outline the next steps in the development process, paving the way for more advanced and robust modeling capabilities.

AC Loss Analysis in Superconducting Cables Carrying Characteristic and Noncharacteristic Harmonic Currents

Harmonic distortions - especially in current waveform - are the inherent nature of any power system such as urban grids, wind farms, electric aircraft, and other electrified transportation units that could change the AC loss value in High Temperature Superconducting (HTS) cables. The aim is to investigate the impact of non-sinusoidal currents with different integer-harmonics, inter-harmonics, and sub-harmonics on the AC loss characteristics of a 22.9 kV, 50 MVA HTS cable. This was accomplished by using an Equivalent Circuit Model (ECM). To do so, current waveforms containing different harmonic components were passed to the ECM of HTS cable. For evaluating the impact of distorted current waveforms on the AC loss of the HTS cable, the ECM was validated by means of Finite Element Method (FEM) in tape level. The results of validation phase have shown a good agreement between the AC loss value derived by ECM and those calculated by FEM published in literature. The results showed that when current waveform was distorted by harmonics, the value of AC loss was changed significantly with respect to variations of harmonic phase angle, order, and amplitude. Results also indicated that 5 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup> harmonic order has the highest impact on the AC loss value and could increase 6% to 80% of AC loss in comparison to pure sinusoidal current. Sub-harmonics and inter-harmonics could also increase the AC loss value to maximum 88% and 64% higher than that of sinusoidal condition.

AC Loss Estimation Model for High-Temperature Superconducting Cables Derived From Experiments Simulating Electromagnetic Environments

In a previous study, the AC loss characteristics of each layer of a high-temperature superconducting (HTS) AC cable were experimentally investigated [1]–[3]. Based on these data, we modeled the AC loss in a superconducting cable by considering the maxi-mum and minimum values of the loss. A comparison between this model and the experimental data showed good agreement. Hence, it is possible to estimate AC loss under electromagnetic conditions in a high-temperature superconducting cable. This model makes it possible to determine the losses of each layer in the superconducting cable and to design the minimum AC loss load of the superconducting cable. This model estimates the AC losses of a three-layer twisted HTS cable.

Automatic Modeling of High-Temperature Superconducting Cable Using Reinforcement Learning

This paper proposes a technique of automatic modeling for high-temperature superconducting (HTS) cables. Reinforcement learning (RL), which is a representative methodology for automation and intelligence, is applied for the automation of the proposed modeling. To reflect the high-frequency characteristics of the HTS cables in the proposed modeling, reflectometry-based cable modeling is used. In addition, for agent training, an environment that combines simulation and experiment results is proposed, and detailed techniques for the process of the proposed RL model are introduced. The proposed technique is demonstrated by experiment using an actual HTS cable under 77 K and 300 K conditions. It is expected that the proposed technique will allow anyone without the related knowledge to perform the modeling of the HTS cables.