S. Y. Wu

Introduction of China's first live grid installed HTS power cable system

Chinas first HTS power cable project was started in the second half of 2002 and on site system installation was finished at Puji Substation of China Southern Power Grid in March, 2004. This cable system consists of three 33.5 m, 35 kV/2 kA/sub rms/ cables, six terminations, and a closed cycle liquid nitrogen cooling station. The conductors of the cables were made of 4 layers of BSCCO 2223 HTS tapes. Off grid field testing and live grid trial operation has been carried out since the completion of the installation. In this paper, we will report the key technical parameters of the system. Descriptions of the installation site, demonstration of the system installation, and results of testing and trial operation will also be presented and discussed.

Recent Main Events in Applied Superconductivity in China

With strong support from Chinese government bodies such as the National High Technology Research and Development Program of China, National Natural Science Foundation of China and the National Basic Research Program of China, the field of applied superconductivity in China has been developed in different areas. Especially in the fusion application area, the first fully-superconducting tokamak, EAST (Experimental Advanced Superconducting Tokamak), has been successfully constructed and commissioned in the last two years. Based on the requirement from the ITER project, high performance Bi-2223 HTS tape, and Nb3Sn and NbTi strands have been developed as well. In the area of HTS applications for electric power systems, R&D has been focused on superconducting power cable, superconducting magnetic energy storage, superconducting transformer, superconducting fault current limiters. In this paper, the recent progress in applied superconductivity in China is reported.

China’s 30 m, 35 kV/2 kA ac HTS power cable project

A project for a 30 m, 35 kV /2 kArms, 3 phase, warm dielectric HTS power cable system is underway in China. This system will be installed in the China Southern Power Grid at the Puji substation in Kunming, Yunan province, in 2004. We have carried out a series of experiments to investigate the possible winding angles and layer configurations of the cable conductor with Ag sheathed Bi-2223 tapes, different LN2 cooling mechanisms, termination configurations, and fabrication techniques. For better understanding of the basics of an HTS cable system and practising new fabrication techniques, a 4 m superconductor cable with terminations and a closed cycle cryogenic system was built and tested. In this paper, we give the detailed parameters of the 30 m cable system and the work plan of the project.

The 50 kA Superconducting Transformer for Testing ITER CC Conductors Short Sample

To meet the specification of International Thermonuclear Experimental Reactor (ITER) Correction Coil (CC) conductors, the 50 kA superconducting transformer has been designed which allows rating of conductor samples during different operating conditions at the Institute of Plasma Physics, the Chinese Academy of Sciences (ASIPP). The superconducting transformer consists of two concentric layer-wound superconducting solenoids with the primary inside the secondary. The 50 kA secondary conductor consists of 4 turns of rectangular cable-in-conduit conductor (CICC) type used of the 0.87 mm NbTi superconductor strands. This paper describes the basic principles of superconducting transformer, the designed concept of the 50 kA superconducting transformer.

Design and Analysis of the Thermal Shield of the Prototype Superconducting Dipole Magnet for GSI

For the prototype superconducting dipole magnet of the collector ring for Gesellschaft für Schwerionenforschung, Germany, the thermal radiation from outside would be shielded by the thermal shield (TS). Considering thermal and mechanical properties, the detailed structure of the TS is discussed. For example, the overview and the design concept of the TS scheme are presented. The layout of the cooling pipe system on the outer and inner surfaces has been considered in terms of the forced-flow liquid nitrogen. Moreover, the multilayer insulation made of aluminized Mylar with woven Dacron netting between the layers is applied to the TSs surface for shielding the thermal radiation. In addition, the eddy-current and mechanical analyses are performed. The cryogenic performance testing indicated that the TS can meet the requirements.

Studies of the spin Hamiltonian parameters for Gd3+ in Pr1.98Gd0.02CuO4

The spin Hamiltonian parameters (i.e., zero-field splittings (ZFSs) b(2)(0), b(4)(0), b(4)(4) and the g factor) for the tetragonal Gd3+ in Pr1.98Gd0.02CuO4 are studied from the superposition model and the approximation formula including admixture of the ground S-8(7/2) and the excited L-6(7/2) (L = P, D, F, G) states via the spin-orbit coupling interactions, respectively. The calculated ZFSs and g factor are in reasonable agreement with the experimental data. It is found that the impurity-ligand bonding angles related to the fourfold (C-4) axis in the impurity Gd3+ centre are about 0.71 degrees smaller than those in the host.

Investigations on the local structure and spin Hamiltonian parameters for the orthorhombic Cu2+ center in Ca(OD)2

AbstactThe local structure and the spin Hamiltonian parameters (the g factors gi (i = x, y, z) and the hyperfine structure constants Ai) for Cu2+-doped Ca(OD)2 are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion in an orthorhombically elongated octahedron. From the studies, the planar Cu2+-OD− bonds are found to experience the relative variation ΔR (≈0.014 Å) along the X and Y axes, while those parallel to the Z axis may undergo the relative elongation ΔZ (≈0.25 Å) due to the Jahn-Teller effect. The theoretical spin Hamiltonian parameters based on the above local lattice distortions agree well with the experimental data. As compared with the previous treatments, the improvements of the theoretical spin Hamiltonian parameters are achieved in this work by adopting the uniform calculation formulas and the tetragonal field parameters based on the superposition model.

Theoretical investigations of the EPR g factors for tetragonal NdBa2Cu3O7-delta

The EPR g factors for the tetragonal NdBa2CU3O7-delta high-T-c superconductor are theoretically investigated on the basis of the perturbation formulae of the g factors for a 4f(3) ion in tetragonal symmetry. The contributions to the g factors arising from the second-order perturbation terms, the admixture of various states and the covalency effect are included in these formulae. The relevant crystal-field parameters are determined from the superposition model and the local structural data of the tetragonal Nd3+ site in NdBa2CU3O7-delta. The calculated g factors are in reasonable agreement with the observed values. The validity of the results is discussed.

The development of 4 m HTS power cable

Superconducting cables offer the advantages of lower loss, lighter weight and smaller dimensions, as compared to conventional cables. A 4 m, 2 kA, AC, HTS cable system was developed for the purpose of study. The cable conductor was made of Bi-2223 tapes. A space maintained as a vacuum between two corrugated stainless steel tubes functions as a cryostat surrounding the superconductor. A closed cycle liquid nitrogen cooling system was exploited. The cable was matched with two terminations, which connect the cable conductor at cryogenic temperature to an outside common electric conductor at room temperature and offer a path for liquid nitrogen. A series of tests were carried out to verify the functions of the system. Important data were obtained which can be used for making longer HTS cable systems.