J. Sheng

Shanghai Jiao Tong University, Shanghai, Shanghai Shi, China

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Publications (30)34.73 Total impact

  • W. Zeng · J. Sheng · J. Ma · Z. Yao · Z.Y. Li · Z. Jin · Z. Hong
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    ABSTRACT: The resistive type superconducting fault current limiter (SFCL) is one of the most important superconducting power applications nowadays. As known, this type of SFCL is settled directly in the power transmission line. When a short fault happens, the temperature of the superconductors in the SFCL will increase sharply due to the huge generated heat. This means the superconductors need time to recover the superconducting properties and be ready for the next short fault. So the recovery characteristics become one of the most crucial features of the resistive type SFCL. In this paper, several different kinds of measuring methods are presented to calculate the recovery time of the HTS tapes, and comparison of these methods is also carried out by a standard test. On basis of this, samples with different kinds of stabilizers are used to explore the influence of stabilizer on their recovery characteristics. In addition, the influence of the encapsulation technology is also discussed in this paper.
    No preview · Article · Jan 2016
  • J. Ma · J. Sheng · Z. Yao · H. Gan · H. Li · X. Ai · Z. Li · Z. Jin · Z. Hong

    No preview · Article · Jan 2016 · IEEE Transactions on Applied Superconductivity

  • No preview · Article · Jan 2016 · IEEE Transactions on Applied Superconductivity

  • No preview · Article · Jan 2016 · IEEE Transactions on Applied Superconductivity

  • No preview · Article · Jan 2016 · IEEE Transactions on Applied Superconductivity
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    ABSTRACT: Joints play an important role in the application of YBaCuO-coated conductors. Given the limited length and various requirements of tapes, large numbers of joints are needed in some applications. Therefore, developing stable joints between tapes and achieving low joint resistance has become an important issue for the application of YBCO tapes. In this paper, we propose a novel superconducting joint production process and fabricate these joints with a lamination machine. A few meters or more than 10 m of joint overlapping length can be achieved, and the joint resistance can be as low as 2.25 nΩ when the overlapping length reaches 8 m. A series of experiments has been carried out to explore the joint resistance changing law, with overlap length increases, and the joint characteristics. The results show that joint resistance is inversely proportional to the overlap length. Although long bridge joints cost more, they have an incomparable advantage in that the joint resistance is distributed over the bridge joint, which allows for more stable operation and less liquid nitrogen boiloff. After joint lamination processing, the burnout current rises from 276 to 523 A. Critical current and joint resistance are not affected by the overcurrent before the joint burns out.
    No preview · Article · Jun 2015 · IEEE Transactions on Applied Superconductivity
  • X. Liu · J. Wen · J. Sheng · W. Zeng · J. Ma · Y. Wang · Z. Y. Li · Z. Jin · Z. Hong
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    ABSTRACT: Quenching characteristic is one of the most important characteristics of superconducting fault current limiters (SFCLs). Recently, the designs of SFCLs have been developing rapidly. Because of the influences of electrical inductance and heat dissipation, different types of SFCL could behave quite differently during quenching process. In this paper, the quenching characteristics of several different individual SFCL modules have been investigated. Special attention has been paid to the limited current and structural features between them. The elementary types of YBCO thin-film wires are solenoid and pancake. Different types of superconducting fault current limiting modules were connected in series to evaluate their advantages and disadvantages. Results in this paper could be helpful to optimize the designs of SFCLs in space utilization and energy efficiency.
    No preview · Article · Jun 2015 · IEEE Transactions on Applied Superconductivity
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    ABSTRACT: This paper focuses on no-insulation (NI) HTS pancake coils with iron core for superconducting dc induction heaters. A superconducting coil without turn-to-turn insulation and its conventional counterpart with insulation are wound with YBCO-coated tapes. An iron core is built for a laboratory-scale dc induction heater. The electromagnetic characteristics of the two coils with the iron core are studied focusing on the charging and sudden-discharging processes at 77 K. Three variables are measured, i.e., current, terminal voltage, and magnetic field induced. The results show that NI coil with the iron core incurs a significant delay in the charging and discharging process due to the influence of the iron core. A terminal voltage pulse is observed at the beginning of the sudden-discharging process, which is more than five times of its normal value. A circuit-field coupled method is proposed to analyze the electromagnetic characteristics of the NI coil with an iron core. The results from experiment and simulation exhibits good agreement. The research shows that it is possible to use the NI technique to build a HTS iron core magnet for a dc induction heater, which can simplify the quench protection system.
    No preview · Article · Jun 2015 · IEEE Transactions on Applied Superconductivity
  • J. Sheng · J. Wen · Y. Wei · W. Zeng · Z. Jin · Z. Hong
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    ABSTRACT: A voltage-source finite-element model of high-temperature superconducting tapes is presented in this paper. This model is a combined model built on both MATLAB and COMSOL, and it is used to study the overcurrent characteristics of non-uniform HTS tapes. The electrical parameters, magnetic distribution, and temperature distribution are separately calculated by different software. The temperature, magnetic flux intensity, and generated heat are set as the intermediate exchange variables. The model accuracy is calibrated and verified by short-circuit experiments of a uniform five-turn HTS solenoid. Then, the basic model is expanded and used to simulate the overcurrent characteristics of nonuniform HTS tapes. Conclusions are provided by considering both simulation and experimental results from these non-uniform tapes, and the results of this study can be used for the design of superconducting devices.
    No preview · Article · Jun 2015 · IEEE Transactions on Applied Superconductivity
  • X. Liu · J. Sheng · Z. Hong · Z. Jin · J. Gu
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    ABSTRACT: With the extensive application of VSC-MTDC (voltage source converter-based multi-terminal direct current) power systems, large DC fault current becomes an important issue due to the bottleneck of DC breaker's capacity. This paper presents an application of SFCL(superconducting fault current limiter) in VSC-MTDC system. A numerical model of SFCL is built in PSCAD and the accuracy of model is verified by a series of experiments. SFCLs are applied in a typical three-terminal HVDC system to study the current limiting effect with different kinds of fault types and fault positions. The simulation results show that the fault current can be limited effectively without affecting the normal operation of the system.
    No preview · Article · Apr 2015
  • J. Wen · B. Lin · J. Sheng · J. Xu · Z. Jin · Z. Hong · D. Wang · H. Zhou · X. Shen · C. Shen
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    ABSTRACT: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (Ic) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the Ic degradation or burnout happens. YBCO coated conductors test in the experiment are from American Superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.
    No preview · Article · Jun 2014 · Physica C Superconductivity
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    ABSTRACT: A dc resistive type superconducting fault current limiter (SFCL) is presented in this paper. This SFCL is designed for the HVDC system. Experiments are conducted to prove the current limiting ability of superconducting materials in dc system. Uniform current and voltage sharing among the SFCL modules can be observed through contact resistance tests, dc flow-through tests, and ac flow-through tests. Results of tests show that each limiting module has good uniformity in higher current system. Then, system simulation model based on these experimental data is built in PSCAD, and simulations are carried out to determine the value of shunt resistor. Results of simulation show that SFCL has fast responding time and good current limiting performance in dc network.
    No preview · Article · Jun 2014 · IEEE Transactions on Applied Superconductivity
  • J. Wen · B. Lin · J. Sheng · L. Ying · L. Yao · Z. Jin · Z. Hong
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    ABSTRACT: In a resistive superconducting fault current limiter (SFCL), the electrodynamic force among the YBCO tapes is enormous when experiencing a high short circuit current, which may cause deformation of tapes and damage of their electrical characteristics. The purpose of this paper is to investigate how much electrodynamic force the YBCO tapes can bear. In this paper, an electrodynamic force simulation model is built to simulate the force, which the two parallel tapes experience and their deformation when short-circuit currents of different value flow through. Then we conducted experiments to observe the deformation of the tapes when they are experiencing a short-circuit current and see if the volt-ampere characteristic of the tapes has a noticeable change after that. Combining the results of the simulation and the experiments, we can obtain the electrodynamic force that tapes can bear. The result can guide us to design the layout of the tapes in the SFCL in accordance with the required fault current level.
    No preview · Article · May 2014 · Journal of Superconductivity and Novel Magnetism
  • J. Sheng · H. Sun · X. Liu · Z. Jin · Z. Hong
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    ABSTRACT: Over-current performance of YBa2Cu3O7-δ tapes under power frequency has been well-studied by previous researches. However, in power grid, superconducting apparatus will also experience lightning impulse current under special working conditions. In this paper, two kinds of lightning impulse current are applied to superconducting testing samples. Comparisons between superconducting characteristics before and after the testing are presented in this paper. Explanations of performance degradation are presented from both the perspectives of temperature and stress mathematic calculation. A maximum endurable value of lightning current which may not cause degradation is obtained from the testing results.
    No preview · Article · Mar 2014 · Applied Physics Letters
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    ABSTRACT: This paper presents a study of frequency dependence of the overcurrent characteristics of high-temperature superconducting (HTS) tape. Fault currents with different amplitudes and frequencies are applied to HTS tape, and the relationship between the overcurrent characteristics and current parameters are obtained after processing and analyzing the experimental results. In addition, a phase difference between the current peak and voltage peak is found in these experiments. Using both simulations and experiments, studies are carried out to find the reason for this phenomenon. Conclusions given in this paper provide useful information for optimizing the design of superconducting apparatus.
    No preview · Article · Jan 2014 · IEEE Transactions on Applied Superconductivity
  • J Sheng · X Qu · X Zhang · Z Zhai · H Li · X Liu · G Liu · Z Zhu · Y Hao · A Qin · K Dai
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    ABSTRACT: The present meta-analysis shows no clear association between coffee consumption and the risk of hip fractures. There was a nonlinear association between tea consumption and the risk of hip fracture. Compared to no tea consumption, drinking 1-4 cups of tea daily was associated with a lower risk of hip fracture. Prospective cohort and case-control studies have suggested that coffee and tea consumption may be associated with the risk of hip fracture; the results have, however, been inconsistent. We conducted a meta-analysis to assess the association between coffee and tea consumption and the risk of hip fracture. We performed systematic searches using MEDLINE, EMBASE, and OVID until February 20, 2013, without limits of language or publication year. Relative risks (RRs) with 95 % confidence intervals (CI) were derived using random-effects models throughout all analyses. We conducted categorical, dose-response, heterogeneity, publication bias, and subgroup analyses. Our study was based on 195,992 individuals with 9,958 cases of hip fractures from 14 studies, including six cohort and eight case-control studies. The pooled RRs of hip fractures for the highest vs. the lowest categories of coffee and tea consumption were 0.94 (95 % CI 0.71-1.17) and 0.84 (95 % CI 0.66-1.02), respectively. For the dose-response analysis, we found evidence of a nonlinear association between tea consumption and the risk of hip fracture (p nonlinearity < 0.01). Compared to no tea consumption, 1-4 cups of tea per day may reduce the risk of hip fracture by 28 % (0.72; 95 % CI 0.56-0.88 for 1-2 cups/day), 37 % (0.63; 95 % CI 0.32-0.94 for 2-3 cups/day), and 21 % (0.79; 95 % CI 0.62-0.96 for 3-4 cups/day). We found no significant association between coffee consumption and the risk of hip fracture. A nonlinear association emerged between tea consumption and the risk of hip fracture; individuals drinking 1-4 cups of tea per day exhibited a lower risk of hip fractures than those who drank no tea. The association between 5 daily cups of tea, or more, and hip fracture risk should be investigated.
    No preview · Article · Nov 2013 · Osteoporosis International
  • Y. Chen · S. Li · J. Sheng · Z. Jin · Z. Hong · J. Gu
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    ABSTRACT: Superconducting fault current limiter (SFCL) has become one of the most ideal current limiting devices to solve the problem of increasing short-circuit current in high-voltage power grid. This paper presents a resistive-type SFCL model developed using simulation software PSCAD/EMTDC. After being verified by finite-element model and experimental results, the model is used to study the impact of SFCLs on the power grid and the co-ordination between SFCL and relay protections in 10 kV distribution network. A series of simulations are carried out to find appropriate parameters of SFCL model to cooperate with relay protection devices. The final result in this paper could provide important quantitative basis of parameters for SFCL to be applied in a real power system.
    No preview · Article · Nov 2013 · Journal of Superconductivity and Novel Magnetism
  • Z. Hong · J. Sheng · Liangzhong Yao · Jhen-Fong Gu · Z. Jin
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    ABSTRACT: This paper presents the design and performance test of a 10 kV, 200 A resistive type superconducting fault current limiter prototype. This is the continued study of the test towards an individual current limiting module, which was done and published in August 2011. The construction of the whole prototype including the cryostat has finished. A series of tests including short circuit test, recovery test, auto-reclosure test, and LN2 boiling test have been performed and the results are presented in this paper. This single phase superconducting fault current limiter is made from 15 current limiting modules. Several 1-m long YBCO coated conductors prepared by Shanghai Jiaotong University are used to build the current limiting module. Each module has 2 tapes connected in parallel to carry 200 A rated current (Ic of each tape is about 150 A) and 6 tapes connected in series to withstand 700 ~ 800 V voltage drop.
    No preview · Article · Jun 2013 · IEEE Transactions on Applied Superconductivity
  • Li Ying · Jie Xu · J. Sheng · Bo Lin · Z. Jin · Z. Hong · Zhuyong Li
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    ABSTRACT: Because of the complexity of the electrical system, dc offset current and ac ripple current have generally existed. However, they are usually undesirable, and their influence to ac loss is also an important issue for superconducting devices built from YBaCuO-coated conductors. In this paper, ac loss of YBCO tapes with nonmagnetic substrate carrying dc or ac offset current have been both measured and calculated. Experiments based on “electrical method” composed of a high-performance amplifier and a wave recorder with filtering function has been carried out. To verify the measurement, a two-dimensional finite element method model based on finite element method and power law is applied to calculate the ac loss with current combined with ac and dc components. The results show that, a small value of dc offset current in a large ac component has minor effect to the ac loss. In addition, when the total current (combined with ac and dc components) approaches critical value, the ac loss would increase significantly.
    No preview · Article · Jun 2013 · IEEE Transactions on Applied Superconductivity
  • J. Duan · L. Zhang · J. Sheng · M. Xing
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    ABSTRACT: The traditional eigenvector method for autofocus can not obtain ideal results in low-SNR (signal-to-noise ratio) cases, because the contribution of the signal in different range bins to the final signal differs greatly. Thus, a weighted eigenvector method for ISAR(inverse synthetic aperture radar) phase error correction is proposed by adding different weights to each range bin according to its SNR. The method can not only deal with normal ISAR signals, but also can handle evenly under-sampled or block sparse, even unevenly sparse data. Finally, actual data processing results confirm the validity of the proposed algorithm.
    No preview · Article · Jun 2013