Numerical Study on AC Loss Properties of HTS Cable Consisting of YBCO Coated Conductor for HTS Power Devices

Cable-in-conduit conductors comprised of twisted stacks of high-temperature superconducting (HTS) tapes constitute a very promising technology by virtue of their easy manufacturing process, flexibility capabilities, and high current densities. In a cable, the current distribution among tapes is one of the key parameters affecting the cable performances. The distribution of current is affected mainly by the self-field configuration (ultimately related to the cable layout) and the termination resistances. In this paper we present a 2D finite element (FE) model, based on the T-A formulation, which computes the magnetic field and current distribution in stacked tapes. This model has been used to describe the experimental V–I results obtained in cables in which different current distributions among tapes are expected. The first case refers to V–I curves of stacks of HTS tapes inserted into ducts formed in the extruded aluminium cylindrical core for a straight cable. The excellent agreement between the experimental findings and the simulation results can be explained in terms of uniform current distribution within the tapes stack, up to the superconducting to normal transition. The second sample, an Al-slotted core Cable-In-Conduit-Conductor, has been bent down to a radius of 0.15 m, and from the measured V–I characteristic of each individual tape, a different tape degradation depending on the tape position within the stack was recorded. The model is able to reconstruct the V–I of the stacks from the characteristic curves of the individual tapes with a satisfactory agreement. The finite element analysis reveals non-uniform current distribution among the tapes, which could expose the cable to a potentially irreversible damage during operation. The proposed FE model constitutes a useful tool for the analysis and predictions of HTS CIC conductor performances and represents a suitable basis for the implementation of more complex models aimed at the design of specific and large applications of this conductor in the next future.

“…The T-A formulation of the Maxwell's equations [42] is a wellestablished model, and it has already been applied to a variety of HTS devices, such as coils [43] and cables [44,45].…”

Section: Methodology and Model Validationmentioning

confidence: 99%

Experimental and numerical studies on current distribution in stacks of HTS tapes for cable-in-conduit-conductors

Marzi¹,

Celentano²,

Augieri³

et al. 2021

“…In [27], 3D electromagnetic numerical models were built based on T-A formulation, to study the AC loss characterization of CORC ® cable, twistedstacked-tape cable (TSTC), and double coaxial cable, under different transport current and external magnetic field. The effect of pitch length in double coaxial cable inner conducting layer was also discussed.…”

Section: Stacked-tape Cablesmentioning

confidence: 99%

The T-A formulation: an efficient approach to model the macroscopic electromagnetic behaviour of HTS coated conductor applications

Huber

Song

Zhang

et al. 2022

In recent years, the T-A formulation has emerged as an efficient approach for modelling the electromagnetic behaviour of high-temperature superconductor (HTS) tapes in the form of coated conductors (CCs). HTS CCs are characterized by an extremely large width-to-thickness ratio of the superconducting layer, normally up to 1000~6000, which in general leads to a very large number of degrees of freedom. The T-A formulation considers the superconducting layer as infinitely thin. The magnetic vector potential A is used to calculate the magnetic field distribution in all simulated domains. The current vector potential T is used to calculate the current density in the superconducting layer, which is a material simulated with a highly nonlinear power-law resistivity. This article presents a review of the T-A formulation. First, the governing equations are described in detail for different cases (2D and 3D, cartesian and cylindrical coordinates). Then, the literature on the implementation of T-A formulation for simulating applications ranging from simple tape assemblies to high field magnets is reviewed. Advantages and disadvantages of this approach are also discussed.

“…To further consider the influence of external magnetic fields, the T-A model proposed by Min Zhang can be used [25]. Several published papers have introduced the availability of this model on AC loss evaluation of CORC cable [26][27][28]. According to the findings from [29,30], the current distribution and overlapping rate also had a great impact on AC loss of CORC cable.…”

Section: Introductionmentioning

confidence: 99%

High temperature superconducting CORC cable with variable winding angles for low AC loss and high current carrying SMES system

Zheng,

Cheng,

et al. 2023

Owing to the rising demand for enhanced high-current capacity within superconducting magnetic energy storage (SMES) system used in power grids, there is a growing focus on enhancing the current-carrying capability of SMES setups wound with conductor on round core (CORC) cables. However, it is crucial to note that the dissipation of AC losses in CORC cables during rapid charge and discharge cycles can substantially impact the safe operation of SMES. The CORC cable is crafted by spirally winding numerous ReBCO tapes around copper tubes. Even slight alterations in the winding angles of these tapes can result in shifts at current distribution across the ReBCO tapes, thus leading to differences in AC losses. Hence, the primary objective of this paper is to study the effect of varying winding angles of each ReBCO layer on AC loss. The adoption of variable angles results in the reduction of current flowing through the outermost tapes. And the AC losses in the outermost tapes happen to account for the majority of the total AC losses. Through simulations and experiments, it was observed that the AC loss in the CORC cable with variable angles (4 × 12, 25°–40°) was 25% lower than that in the case of fixed angles (3 × 11, 45°). These findings demonstrate a noteworthy downward trajectory in AC losses when variable angles are applied to the CORC cable. These insights hold significant value for the practical application of CORC cables within SMES systems.