An accurate model of the high-temperature superconducting cable by using stochastic methods

Modeling of high-temperature superconducting (HTS) cables as key elements of future power grids is a remarkable step at the beginning of projects on superconducting cables. Many projects utilize finite element methods (FEMs) to better understand the cable loss mechanism and its value. These methods are unable to evaluate the behavior of cables while connecting to a real grid. Therefore, equivalent circuit models (ECMs) are introduced as variants to provide a suitable environment for testing capabilities of high-temperature superconducting cables under different contingencies of power grids. This advantage has raised interest in the utilization of ECMs to predict the behavior of HTS cables. The accuracy of modeling by ECMs depends on many factors and considerations, among which twisting effect is a vital factor that is able to highly impress the accuracy of simulations. Thus, the Weibull distribution function (WDF) is utilized in this paper as a stochastic solution to increase the accuracy of the model. By applying WDF and sectionizing tapes, the twisting effect on the critical current of cable is accessible. Investigations on different conditions have shown that an ECM with 100,000 sections has high accuracy and acceptable speed

An accurate model of the high-temperature superconducting cable by using stochastic methods

Modeling of high-temperature superconducting (HTS) cables as key elements of future power grids is a remarkable step at the beginning of projects on superconducting cables. Many projects utilize finite element methods (FEMs) to better understand the cable loss mechanism and its value. These methods are unable to evaluate the behavior of cables while connecting to a real grid. Therefore, equivalent circuit models (ECMs) are introduced as variants to provide a suitable environment for testing capabilities of high-temperature superconducting cables under different contingencies of power grids. This advantage has raised interest in the utilization of ECMs to predict the behavior of HTS cables. The accuracy of modeling by ECMs depends on many factors and considerations, among which twisting effect is a vital factor that is able to highly impress the accuracy of simulations. Thus, the Weibull distribution function (WDF) is utilized in this paper as a stochastic solution to increase the accuracy of the model. By applying WDF and sectionizing tapes, the twisting effect on the critical current of cable is accessible. Investigations on different conditions have shown that an ECM with 100,000 sections has high accuracy and acceptable speed

AC loss analysis in superconducting cables carrying characteristic and non-characteristic 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 th 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

DC electro-magneto-mechanical characterisation of 2G HTS tapes for superconducting cable in magnet system using artificial neural networks

Characterization of the exact critical current density (Jc) and stress values in twisted superconducting tapes plays an important role for analysing their magnetic, thermal, and mechanical behaviours. In this paper, a model based on Artificial Neural Network (ANN) is introduced to estimate the electro-magneto-mechanical characteristic of different superconducting tapes. For this purpose, magnetic flux density, temperature, strain, total thickness of tape, their width, thickness of stabilisers, and thickness of substrates are used as inputs to ANN model whilst minimum normalised Jc and maximum stress are considered as outputs. The required experimental data are extracted from published papers in literature. The ANN model was trained for Jc/stress estimation using extracted data for different inputs. Sensitivity analysis was conducted on ANN models which were used to estimate the Jc and stress values of tapes, to choose an optimum structure for ANN models to be used in future by other scientists in the superconductivity community. To check the reproducibility, repeatability, and stability of presented results, the estimations with ANN optimum structure were tested for 500 testing runs. We found that the ANN optimum structure was as 1 hidden layer with Levenberg-Marquardt training method and 7 inputs. Comparing to the literature, the proposed ANN model offers about 15% and 1.1% higher accuracy in Jc and stress estimations, respectively

High temperature superconducting cables and their performance against short circuit faults: current development, challenges, solutions, and future trends

Along with advancements in superconducting technology, especially in high-temperature superconductors (HTSs), the use of these materials in power system applications is gaining outstanding attention. Due to the lower weight, capability of carrying higher currents, and the lower loss characteristic of HTS cables, compared to conventional counterparts, they are among the most focused large-scale applications of superconductors in power systems and transportation units. In near future, these cables will be installed as key elements not only in power systems but also in cryo-electrified transportation units, that take advantage of both cryogenics and superconducting technology simultaneously, e.g., hydrogen-powered aircraft. Given the sensitivity of the reliable and continuous performance of HTS cables, any failures, caused by faults, could be catastrophic, if they are not designed appropriately. Thus, fault analysis of superconducting cables is crucial for ensuring their safety, reliability, and stability, and also for characterising the behaviour of HTS cables under fault currents at the design stage. Many investigations have been conducted on the fault characterisation and analysis of HTS cables in the last few years. This paper aims to provide a topical review on all of these conducted studies, and will discuss the current challenges of HTS cables and after that current developments of fault behaviour of HTS cables will be presented, and then we will discuss the future trends and future challenges of superconducting cables regarding their fault performance

Investigation on the electrothermal performance of a high temperature superconducting cable in an offshore wind farm integrated power system: fault and islanding conditions

The main contribution of this paper is to study the electrothermal performance of a 22.9 kV High Temperature Superconducting (HTS) AC cable under transients such as short circuit faults and Islanding Operating Mode (IOM) of a wind farm. For this purpose, an HTS cable connects a 12 MVA doubly-fed induction generator-based wind farm to the load centre, under two different scenarios of the network. In the first scenario, the upstream grid is located far away from the load centre and most of the demanded load is supplied by the wind farm while in the second scenario, part of the load is supplied by the wind farm and the rest is supplied by the upstream grid located near the load centre. In case of faults and transients in upstream grid, protection systems isolate the wind farm and thus it operates in a specific mode, called as IOM. Results indicated that the location of faults and transients especially IOMs play a significant role in the electrothermal performance of HTS cable