Cable Prototype Research Articles

Electric Measurement of the Critical Current, AC Loss, and Current Distribution of a Prototype HTS Cable

HTS cable is an emerging technology for electricity power transmission. It is very important to set up an accurate and easy-to-build measurement system to characterize HTS cables. In this paper, a novel measurement system has been developed to measure the ac losses for a prototype HTS cable using cancelation coil technique. This system is based on the National Instrument Data Acquisition card. It can also be used to measure the critical current and current distribution in the prototype cable. The prototype cable has been innovatively designed using an improved particle swarm optimization algorithm which is more computationally efficient than conventional methods. The measurement system will be improved further by introducing an elaborate pre-amplifier prior to data collection process and the result will be compared with theoretical calculations for validation.

Testing Results for the Cable Core of a 360 m/10 kA HTS DC Power Cable Used in the Electrolytic Aluminum Industry

IEE has installed a 360-m-long high-temperature superconducting (HTS) dc power cable at the self-supply power plant of Zhongfu Industrial Co., Ltd. in Gongyi, Henan. The cable connects a 19.5 MVA/1.5 kA silicon-controlled rectifier, which connects with a 110 kV/1 kV transformer, to the bus bar of an electrolytic aluminum cell. It is designed to carry 10 kA current and the voltage is 1300 V. The HTS dc power cable core consists of five conductor layers wound with the spliced Bi-2223 wires with the length of 40 km. The cable core has five layers and 23 HTS wires in each layer with the outer diameter of 45 mm. As the items in this project, testing of 4 to 5 m length prototype cables, including a 5 m prototype cable fabricated before the 360 m power cable and a 4 m prototype cable intercepted from the 360 m HTS power cable, is conducted. These prototypes are used to assess the design program, fabrication process, and performance of the 360 m/10 kA HTS power cable including steady state operation at the 10 kA design current and overcurrent fault capability. The critical current of the 5 and 4 m HTS power cable reach 14.3 kA and 13.8 kA at 77 K, 1 μV/cm, respectively. In this paper, the design parameters and fabrication of the 360 m/10 kA HTS dc power cable conducted by IEE are presented. The cable system, installation process and the summary of the results from the testing of 4 and 5 m prototype cables are described. In addition, details of the initial cool-down process and energizing are presented.

$\hbox{MgB}_{2}$ Hollow Wires and Cables Embedded in a Mg Alloy Matrix

The brittleness of the MgB2 wires prevents performing a cable architecture with very small bending radius, similar to NbTi Rutherford cables. Consequently, it is important to reduce the thickness of the superconducting materials in order to increase its bending strain limit. In this context, thin Ni sheathed MgB2 hollow wires, having wall thickness of the order of 20 μm and length of the order of 100 m, have been produced by the Reactive Mg-Liquid Infiltration process (Mg-RLI). The latest hollow monofilament made by Mg-RLI shows very high transport properties, having an engineering critical current density at 4.2 K, 3 T of 730 A/mm2. In this wire the small thickness of the MgB2 corona allows a twisting with pass of the order of a few cm and fulfils the thermal stability criterion for MgB2. We have demonstrated that cables made by such braided or twisted wires may be conveniently reinforced, by embedding the wires in a molten Mg bath, so that the Ni sheath is almost completely dissolved and the wires are clad by an eutectic Mg10%at Ni alloy. This alloyed matrix is structurally well connected to the MgB2 material, with minimal thermal and electrical resistance at the interface. A cable prototype based on this metallic composite has been prepared with 21 mono-core MgB2 wires, twisted around a central hole, which may be useful for cooling purposes. This cable design may be applied as current leads or in short bus-bars, for high current supply.

Vibration control of cables with damped flexible end restraint: Theoretical model and experimental verification

This paper presents the theoretical formulation and associated numerical and experimental studies on a novel passive control approach to reducing cable vibrations. In this approach, a damped flexible restraint consisting of a viscous damper and an elastic spring is attached to the end of cable in the horizontal direction to suppress its transverse vibrations. The dynamic equations of the cable-restraint system are established by D'Alembert's principle and then transformed into a set of ordinary differential equations through Garlerkin method. These equations are subsequently solved using the Runge–Kutta method. Parametric studies on a prototype cable are performed to investigate the influence of various parameters, particularly the damper coefficient and the spring stiffness, on the suppression of the cable vibrations. A series of laboratory experiments have also been carried out on a 9.5m scaled cable with the installation of a damped flexible end restraint. The effectiveness of the approach has been verified from the experiments in that a system damping ratio of order of 2% was obtained. The experimental observations are found to be in good agreement with the theoretical predictions.

Utilizing cable winding and industrial robots to facilitate the manufacturing of electric machines

Cable wound electric machines are used mainly for high voltage and direct-drive applications. They can be found in areas such as wind power, hydropower, wave power and high-voltage motors. Compared to conventional winding techniques, cable winding includes fewer manufacturing steps and is therefore likely to be better suited for automated production. Automation of the cable winding production step is a crucial task in order to lower the manufacturing costs of these machines. This article presents a production method using industrial robots for automation of cable winding of electric machine stators. The concept presented is validated through computer simulations and full-scale winding experiments, including a constructed robot-held cable feeder tool prototype. A cable wound linear stator section of an Uppsala University Wave Energy Converter and its winding process is used as a reference in this article. From this example, it is shown that considerable production cycle time and manufacturing cost savings can be anticipated compared to manual winding. The suggested automation method is very flexible. It can be used for the production of cable wound stators with different shapes and sizes, for different cable dimensions and with different winding patterns. ► Utilizing cable winding in stators is likely to facilitate automated assembling. ► A robot automated manufacturing method for cable winding is presented. ► Computer simulations and prototype experiments validate the automation method. ► An Uppsala University Wave Energy Converter cable wound stator is used as reference. ► Automation method can be used for different stator designs and winding patterns.

Overview of Superconductivity and Challenges in Applications

Considerable progress has been achieved during the last few decades in the various fields of applied superconductivity, while the related low temperature technology has reached a high level. Magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) are so far the most successful applications, with tens of thousands of units worldwide, but high potential can also be recognized in the energy sector, with high energy cables, transformers, motors, generators for wind turbines, fault current limiters and devices for magnetic energy storage. A large number of magnet and cable prototypes have been constructed, showing in all cases high reliability. Large projects involving the construction of magnets, solenoids as well as dipoles and quadrupoles are described in the present book. A very large project, the LHC, is currently in operation, demonstrating that superconductivity is a reliable technology, even in a device of unprecedented high complexity. A project of similar complexity is ITER, a fusion device that is presently under construction. This article starts with a brief historical introduction to superconductivity as a phenomenon, and some fundamental properties necessary for the understanding of the technical behavior of superconductors are described. The introduction of superconductivity in the industrial cycle faces many challenges, first for the properties of the base elements, e.g. the wires, tapes and thin films, then for the various applied devices, where a number of new difficulties had to be resolved. A variety of industrial applications in energy, medicine and communications are briefly presented, showing how superconductivity is now entering the market.

Periodically structured thin-film cables

Periodic structuring of the ground plane is presented as a method of adjusting the properties of thin-film microstrip cables. Such cables may be useful as interconnects when flexibility is required and space is at a premium. Simple analytic models are presented and verified by numerical simulation. Prototype cables are fabricated in 2 m lengths of copper-clad polyimide. The effect of dimensions on characteristic impedance, cut-off frequency and propagation loss is investigated, and it is shown that impedance close to 50 may be combined with low loss, using feature sizes compatible with flexible printed circuit board (PCB) fabrication.

AC loss of a model 5m 2G HTS power cable using wires with NiW substrates

A model 5 m cable prototype was constructed using American Superconductor second generation (2G) high temperature superconductor (HTS) wires – 344 superconductors, produced with the MOD/RABiTSTM process. The model cable consists of two helically counterwound layers of brass-laminated tapes. Twist pitches were calculated to provide uniform current distribution between the two cable layers. The NiW substrates of the tapes were oriented to face radially inward and radially outward for the inner and outer layers of the cable, respectively, to minimize the spacing between the HTS layers and any effects of the weak substrate magnetism. To verify the calculations and design principles, the model cable was instrumented with potential taps and sensors, including Rogowski coils and Hall probes, to measure the current distribution among layers, voltage – current characteristics and other parameters. AC losses in this cable model have been measured and analyzed by use of digital measurements of current and voltage. At low to intermediate currents, they are in the range of a few tenths of a watt per meter, consistent with the ferromagnetic loss of the substrate. Analysis of the individual contributions of the Ni-W substrate and the superconductor hysteresis loss is given.

Qualification High Voltage Testing of Short Triax HTS Cables in the Laboratory

In order to qualify the electrical insulation design of future HTS cables installed in the electric grid, a number of high voltage qualification tests are generally performed in the laboratory on either single-phase model cables and/or actual three-phase cable samples. Prior to installation of the 200-m Triax HTS cable at the American Electric Power Bixby substation near Columbus, Ohio, in September, 2006, such tests were conducted on both single-phase model cables made at ORNL and tri-axial cable sections cut off from cable made on a production run. The three-phase tri-axial design provides some specific testing challenges since the ground shield and three phases are concentric about a central former with each phase separated by dielectric tape insulation immersed in liquid nitrogen. The samples were successfully tested and qualified for partial discharge inception, AC withstand, and lightning impulse where voltage is applied to one phase with the other phases grounded. In addition one of the phase pairs was tested for dc withstand as a ldquoworst caserdquo scenario to simulate the effect of VLF (Very Low Frequency) tests on the actual cable installed at the Bixby site. The model and prototype cables will be described and the high voltage test results summarized.

YBa2Cu3O7−δ coated conductor cabling for low ac-loss and high-field magnet applications**Contribution of NIST, a US government agency, not subject to copyright. Certaincommercial materials are referred to in this paper to foster understanding. Suchidentification does not imply recommendation or endorsement by NIST, nor does it implythat the materials identified are necessary the best available for the purpose.

The electromechanical properties ofYBa2Cu3O7−δ coated conductors under high axial compressive strain are measured;they show no irreversible degradation in critical current up to−2% strain. The high degree of elasticity of the ceramic layers in these conductors isbeneficial when used in high-field applications, but has not been fully exploited. Theresults presented here lead to the introduction of a new method of producingYBa2Cu3O7−δ coated conductor cabling for use in low ac-loss and high-field magnet applications, wherecoated conductors are wound around a former with a relatively small diameter. Thisconcept allows for full transposition of the conductors, a high cable critical current, lowinductance, and a relatively high engineering current density. The feasibility of theconcept is demonstrated by constructing several prototype cables and by comparingthe cable critical current to that of a straight sample under axial compression.

2P1-B04 簡易な形状情報を用いた能動スコープカメラの滑り運動制御

We propose a new framework for a self-propelled flexible cable in which the freedom of lateral motion with sliding movements is increased on the basis of simple shape information. The motion control method focused on the shape and length of the straight element and used sideslip of active flexible cable. We applied the method to control the running direction. We developed a large-scale prototype of the flexible cable that has a ciliary drive mechanism and precise shape sensors to investigate our concept. The experimental results demonstrated the effectiveness of sliding motion for controlling the running direction. Further, we developed a kinetic model for the prototype by employing the nonlinear driving force model and the lateral friction model for representing slippages. We implemented and analzed the model with Open Dynamics Engine (ODE). By experimental of simulation and actual equipment, we evaluated the parameter used in shape information handling for optimizing the motion control. Getting the shape information by the feature point tracking, we consider for applying this motion control method to actibe scope camera.

Experimental study of wind–rain-induced cable vibration using a new model setup scheme

Wind–rain tunnel test of cable section model is one of the effective ways to explore mechanism of wind-rain-induced cable vibration and its mitigation. However, most of previous model setup schemes consider vertical vibration of cable only, in which the restoring force comes from the springs that perpendicularly support the cable model at its two ends. In this short communication, a new setup scheme for experimental study of wind–rain-induced cable vibration is presented. It can simulate both horizontal and vertical vibrations of the cable, in which the restoring force of the cable model comes from cable tension forces as in the prototype cable. Furthermore, the new setup can be easily adjusted for different cable inclinations and yaw angles. The frequency equation of the cable model is first derived to facilitate the design of model setup. Vortex-induced cable vibration, galloping of cable with artificial rivulet and wind–rain-induced cable vibration are then reproduced in wind/wind–rain tunnel using the new setup scheme. The preliminary parameter study, including cable inclination, yaw angle, and rainfall, regarding wind–rain-induced cable vibration is also performed. The effectiveness of vibration control methods, such as increasing damping ratio and twining spiral wire on the cable surface, is finally investigated.

Cable R&D for the LHC Accelerator Research Program

Future luminosity upgrades for the LHC at CERN will require higher field magnets than those presently being utilized. The US LHC Accelerator Research Program (LARP) is addressing this need with the design and fabrication of prototype quadrupole magnets utilizing Nb3Sn technology. A part of the R&D effort is the development of suitable cables for the magnet designs being considered by LARP. The cable parameter limits for LARP prototype and production cables are presented. At present the standard strand for LARP is the Restack Rod Processed (RRP) strand being produced by Oxford Superconducting Technologies. The present strand has 54 sub-elements and 53% Cu. An optimal cable for the first generation of LARP quadrupole magnets has a width of 10 mm, thickness of 1.26 mm, and a keystone angle of 1 degree. This work shows that if a strand is properly cabled a nearly degradation-free mechanically-stable cable can be produced.

Triaxial HTS Cable for the AEP Bixby Project

Ultera has installed a single 200-meter long high temperature superconducting (HTS) 3-phase triaxial design cable at the American electric power (AEP) Bixby substation in Columbus, Ohio. The cable connects a 138/13.2 kV transformer to the distribution switchgear serving seven outgoing circuits. It was designed to carry 3000 Arms. Testing of 3- to 5-meter length prototype cables, including a 5-meter prototype with full scale terminations tested at ORNL was conducted prior to the manufacture and installation of the AEP triaxial cable. These prototypes were used to demonstrate the crucial operating conditions including steady state operation at the 3000 Arms design current, high voltage operation, high voltage withstand and 110 kV impulse, and overcurrent fault capability. A summary of the results from the thermal analysis and testing conducted by Ultera and ORNL will be presented. Some analysis of the cable thermal-hydraulic response based on the testing that were used to determine some of the cable cryogenic system requirements are also presented.

Recent Development of Magnet Technology in China: Large Devices for Fusion and Other Applications

The projects for large science devices and industrial applications are strongly driving the progress of superconductivity and magnet technology in China. One example is the EAST Tokamak-the biggest superconductivity project in China. The magnet system of EAST consists of twenty-eight large superconducting coils. The technology of superconducting magnet for fusion device is well developed. At same time, three accelerator projects are funded: the HIRFL-CSR, a cooler storage ring for the Heavy Ion Research Facility has been built and its commissioning is starting; the BEPCII High Luminosity Double ring Collider and its superconducting BESIII detector magnet are in progress; The Shanghai Synchrotron Radiation Facility (SSRF) project is going on. The proposed high magnetic field laboratory project would bring along the magnet technology further. The R&D for prototype of power cable, transformer, fault current limiter and SMES show good possibility of application of HTS in the future. The recent development of magnet technology in China is introduced in this paper

State-Derivative Feedback Control of Cable Vibration Using Semiactive Magnetorheological Dampers

Abstract: This article presents the theoretical and in situ experimental studies on state-derivative feedback control of bridge cable vibration using semiactive magnetorheological (MR) dampers. The semiactive feedback control is accomplished using only one MR damper and one accelerometer collocated near the lower end of the cable. Within the framework of reciprocal state space (RSS), the linear quadratic regulator (LQR) control technique is applied to formulate state-derivative feedback control law and derive the feedback and estimator gains for real-time control of cable vibration using MR dampers. The state-derivative feedback control strategy directly uses acceleration information for feedback and state estimation, which is usually the only measure available in practical cable vibration control implementation. More importantly, the control force commanded by the state-derivative feedback control strategy based on energy weighting is a dissipative force except for low velocity and small force, which is therefore implementable by the semiactive MR dampers without clipping. Numerical simulations of state-derivative feedback control for a stay cable in the cable-stayed Dongting Lake Bridge are conducted under sweeping sine excitation and sinusoidal step relaxation excitation, and then the experimental validation of the prototype cable is carried out in the bridge site with the help of the real-time control system dSPACE. Good agreement between the simulation and experimental results is observed.

On the Effect of NiW on the Inductance and AC Loss of HTS Cables

The impact of Ni-5at%W substrates on ac loss and inductance of HTS cables was examined. Two 1.2-m prototype cables were made with stainless steel laminated BSCCO tapes and were wound on a 25.4 mm diameter former. Each cable consisted of two layers of 15 BSCCO tapes wound at opposite lay angles and has an estimated critical current of 3000 A at 77 K. One cable had four additional layers of 4.8 mm wide Ni-5at%W tape co-wound with the BSCCO tapes to simulate a commercial second generation HTS cable. The Ni-5at%W tapes had the same width as the BSCCO and a thickness of 50 microns. Through the use of a coaxial copper ground, the cable inductance was measured at room temperature and liquid nitrogen (77 K) using high frequency rf measurement techniques. Experimental results for the cable inductance and ac loss were compared against numerical calculations to determine the significance of the Ni-5at%W substrate contribution. Results indicate that inductance and ac loss changes from these substrates in commercial cables should be small.

Tests of Tri-Axial HTS Cables

The Ultera/ORNL team have built and tested 3-m and 5-m triaxial cables rated at 3 and 1.3 kA-rms, respectively. The three concentric superconducting phases are made of BSCCO-2223 HTS tapes, separated by layers of cold-dielectric tapes. A copper braid is added as the grounding shield on the outside of the three active phases. Tests of these cables were performed at temperatures ranging from 70 to 84 K. AC loss data reconfirmed the previous result on a 1.5-m prototype cable that the total 3-phase ac loss is about the sum of the calculated ac losses of the three concentric phases. These and other test results of the 1.3 and 3 kA cables will be used to construct a second 5-m triaxial cable rated at 3 kA-rms, 15 kV. Preliminary test results supporting this new cable and the associated termination are summarized.

Advanced optical technologies for monitoring estuaries and coastal environments

In recent years the need to monitor different parameters has led to the development of several architectures able to make real time, un-attended measurements. Particularly in regard to environmental issues, it is very important that the equipment and measuring systems be small and light to avoid maximum interference of the ecosystems studied. In this context, optical fibre sensors have become extremely attractive for use in natural environments to monitor different parameters of biological interest, due to their intrinsic small weight and size and low reactivity to chemical and biological parameters. In this paper we present an innovative and technologically advanced system for the simultaneous measurement of temperature and salinity based on optical fibre Bragg grating sensors and on an optical sensing cable especially designed for large-scale and distributed or quasi-distributed measurements. A prototype of this optical cable was installed in the Mira Channel at Ria de Aveiro, Portugal. Temperature variation during three weeks from 4 to 23 June 2002 is investigated and presented here.

Optimal design of viscous dampers for multi-mode vibration control of bridge cables

Viscous dampers have been widely used for mitigating rain–wind-induced vibration of bridge stay cables. Designing a damper with optimal damping in a specific mode may leave the cable susceptible to vibration in other modes, and it is almost impossible to specify a priori the dominant mode in which optimal performance should be achieved. In the present paper, a new method for optimal design of viscous dampers to achieve multi-mode cable vibration control is developed. With reference to a cable–damper model taking into account cable sag, inclination and bending stiffness, a method to determine the optimal damper size for cable vibration control in assigned multiple modes is proposed based on optimal LQG control theory. The system damping ratios obtained from the proposed strategy are thus found to satisfy the Irwin’s criterion for all the assigned modes. Case studies of prototype cables on a real cable-stayed bridge which experienced rain–wind-induced oscillation show the efficiency of the proposed method.