Showing papers in "IEEE Transactions on Applied Superconductivity in 2012"
CERN1
TL;DR: In this article, the authors reviewed the last ten year of Nb3Sn accelerator magnet R&D and compared it to the needs of the upgrades and critically assessed the results of the Nb 3Sn and HTS technology and the planned R&DD programs also based on the inputs of first year of LHC operation.
Abstract: The Large Hadron Collider is working at about half its design value, limited by the defective splices of the magnet interconnections. While the full energy will be attained after the splice consolidation in 2014, CERN is preparing a plan for a Luminosity upgrade (High Luminosity LHC) around 2020 and has launched a pre-study for exploring an Energy upgrade (High Energy LHC) around 2030. Both upgrades strongly rely on advanced accelerator magnet technology, requiring dipoles and quadrupoles of accelerator quality and operating fields in the 11-13 T range for the luminosity upgrade and 16-20 T range for the energy upgrade. The paper will review the last ten year of Nb3Sn accelerator magnet R&D and compare it to the needs of the upgrades and will critically assess the results of the Nb3Sn and HTS technology and the planned R&D programs also based on the inputs of first year of LHC operation.
208 citations
TL;DR: In this article, the design and fabrication of a 32 T, 32 mm cold bore superconducting magnet with high field REBCO inner coils is underway at the NHMFL.
Abstract: The design and fabrication of a 32 T, 32 mm cold bore superconducting magnet with high field REBCO inner coils is underway at the NHMFL. In support of the design, conductor characterization measurements have been made including critical current as a function of field, field orientation, temperature, and strain on conductors and joints. Various conductor and turn insulation systems were examined. The selected coil fabrication method for the 32 T magnet is pancake wind, dry wind coils with sol-gel insulation on a stainless steel co-wind. Quench protection of the REBCO coils by distributed heaters is under development. Small REBCO coils have been made and tested in a 20 T background field to demonstrate performance of the technology. The design of the 32 T magnet is described, including coil configuration and conductor lengths, fraction of critical current, selection of conductor copper content for protection, and stress in the windings.
194 citations
ITER1
TL;DR: The ITER magnet procurement is now well underway and the production of the first components is underway and manufacturing prototypes of TF coil components are being completed, and the paper will present a design overview and the manufacturing status.
Abstract: The ITER magnet procurement is now well underway. The magnet systems consist of 4 superconducting coil sets (toroidal field (TF), poloidal field (PF), central solenoid (CS) and correction coils (CC)) which use both NbTi and Nb3Sn-based conductors. The magnets sit at the core of the ITER machine and are tightly integrated with each other and the main vacuum vessel. The total weight of the system is about 10000 t, of which about 500 t are strands and 250 t, NbTi. The reaction of the magnetic forces is a delicate balance that requires tight control of tolerances and the use of high-strength, fatigue-resistance steel forgings. Integration and support of the coils and their supplies, while maintaining the necessary tolerances and clearance gaps, have been completed in steps, the last being the inclusion of the feeder systems. Twenty-one procurement agreements have now been signed with 6 of the ITER Domestic Agencies for all of the magnets together with the supporting feeder subsystems. All of them except one (for the CS coils) are so-called Build to Print agreements where the IO provides the detailed design including full three-dimensional CAD models. The production of the first components is underway (about 175 t of strand was finished by July 2011) and manufacturing prototypes of TF coil components are being completed. The paper will present a design overview and the manufacturing status.
178 citations
TL;DR: The ITER magnet coils are wound from Cable-In-Conduit Conductors (CICC) made up of superconducting and copper strands assembled into a multistage, rope-type cable inserted into a conduit of butt-welded austenitic steel tubes as discussed by the authors.
Abstract: The ITER magnet coils are wound from Cable-In-Conduit Conductors (CICC) made up of superconducting and copper strands assembled into a multistage, rope-type cable inserted into a conduit of butt-welded austenitic steel tubes. The conductors for the Toroidal Field (TF) and Central Solenoid (CS) coils require about 500 tons of Nb3Sn strands while the Poloidal Field (PF) and Correction Coil (CC) conductors need around 250 tons of Nb-Ti strands. The required amount of Nb3Sn strands far exceeds pre-existing industrial capacity and calls for a significant worldwide production scale up. After explaining the in-kind procurement sharing of the various conductor types among the six ITER Domestic Agencies (DA) involved: China, Europe, Japan, South Korea, Russia, and the United States, we detail the technical requirements defined by the ITER International Fusion Energy Organization (IO), and we present a brief status of ongoing productions. The most advanced production is that for the TF conductors, where all six DAs have qualified suppliers and about 50% of the required strands have been produced and registered into the web-based conductor database developed by the IO.
158 citations
TL;DR: A superconducting magnetic energy storage (SMES) unit is proposed to improve the dynamic performance of a wind energy conversion system equipped with DFIG during voltage sag and voltage swell events.
Abstract: The integration of wind turbines into modern power grids has significantly increased during the last decade. Wind turbines equipped with doubly fed induction generators (DFIGs) have been dominating wind power installation worldwide since 2002. In this paper, a superconducting magnetic energy storage (SMES) unit is proposed to improve the dynamic performance of a wind energy conversion system equipped with DFIG during voltage sag and voltage swell events. The converter and the chopper of the SMES unit are controlled using a hysteresis current controller and a fuzzy logic controller, respectively. Detailed simulation is carried out using MATLAB/SIMULINK software to highlight the impact of the SMES unit in improving the overall system performance under voltage sag and voltage swell conditions.
134 citations
TL;DR: A no-insulation (NI) technique has been applied to wind and test a NI HTS (YBCO) double-pancake coil, which has little detrimental effect on field-current relationship and a net result will be a significant reduction in the overall cost of an LTS/HTS NMR magnet, at 1.3 GHz and above.
Abstract: A no-insulation (NI) technique has been applied to wind and test a NI HTS (YBCO) double-pancake coil at 4.2 K. Having little detrimental effect on field-current relationship, the absence of turn-to-turn insulation enabled the test coil to survive a quench at a coil current density of 1.58 kA/mm2. The NI HTS coil is compact and self-protecting, two features suitable for large high-field magnets. To investigate beneficial impacts of the NI technique on >;1 GHz LTS/HTS NMR magnets, we have designed six new NI HTS inserts for our ongoing 1.3 GHz LTS/HTS NMR magnet, which require less costly LTS background magnets than the original insulated HTS insert. A net result will be a significant reduction in the overall cost of an LTS/HTS NMR magnet, at 1.3 GHz and above.
129 citations
TL;DR: In this paper, a study on BSCCO and ReBCO HTS (high temperature superconducting) test coils, layer-wound and double-pancake, with and without turn-to-turn insulation, was performed in a bath of liquid nitrogen to compare stabilities of the test coils at 77 K.
Abstract: This paper reports a study on BSCCO and ReBCO HTS (high temperature superconducting) test coils, layer-wound and double-pancake, with and without turn-to-turn insulation. Over current tests were performed in a bath of liquid nitrogen to compare stabilities of the test coils at 77 K. Saturation of magnetic fields from the NI (no insulation) coils, both BSCCO and ReBCO, was observed owing to current bypassing through turn-to-turn contacts in local quenches at operating currents higher than their critical currents. In the NI ReBCO coils, global quenches occurred at operating currents higher than the coil critical currents and quench recoveries were observed during discharge of the coils. The experimental results, obtained to date, demonstrate that the NI winding method enables remarkable improvement of thermal stability of the HTS coils.
118 citations
TL;DR: In this article, two HTS racetrack coils wound with GdBCO coated conductors, one without turn-to-turn insulation and the other with Nomex insulation, were characterized by charge-discharge, overcurrent and sudden discharge tests.
Abstract: This paper reports a study of two HTS racetrack coils wound with GdBCO coated conductors, one without turn-to-turn insulation and the other with Nomex insulation. The coils were characterized by charge-discharge, over-current, and sudden discharge tests. Thermal and electrical characteristics of the GdBCO racetrack coil without insulation outperformed the insulated one. The test results confirmed that although the coil without insulation has a slow charging/discharging time constant, the no-insulation winding technique may enable a compact and protection-free racetrack-typed coil with enhanced mechanical integrity as well as better thermal and electrical stabilities.
111 citations
TL;DR: In this paper, a 10 MW class fully superconducting synchronous machine for direct-drive wind turbine generators was designed using two kinds of super-conducting wires, including multifilament wires for armature windings and HTS tapes for DC field coils.
Abstract: We have studied a 10 MW class fully superconducting synchronous machine for direct-drive wind turbine generators. This machine has been designed using two kinds of superconducting wires. Multifilament wires have been used for armature windings. The DC field coils of the machine rotor are made of HTS tapes. Electromagnetic design of the generators has been carried out by FEM analysis. Analysis results show that 10 MW output is achievable with less use of HTS tapes than wind turbine generators having superconducting field coils and copper armature windings. Then, calculated AC losses are low.
88 citations
TL;DR: In this paper, the authors proposed an application of superconducting flywheel energy storages (SFESs) to compensate the power fluctuation of the large scale wind farm.
Abstract: This paper proposes an application of superconducting flywheel energy storages (SFESs) to compensate the power fluctuation of the large scale wind farm. Based on the global interest against global warming, the power capacity of the renewable generation, especially wind generation, has been increased steeply. However, since wind generations depend on the natural wind speed completely, the power output cannot be controlled. The power fluctuation caused by the non-controllable output characteristic may create voltage problem for local system and frequency problem for whole power system. To solve those problems, the hybrid application of the large-capacity battery energy storage system (BESS) and the high-speed superconducting flywheel energy storage system (SFES) are considered in Heangwon wind farm in Cheju Island in Korea. Through the case studies based on the site-measured output data, the optimal power and energy capacity of the BESSs and SFES are figured out.
86 citations
TL;DR: In this paper, three modes of HTS linear synchronous motor (HTSLSM) integrated with HTS magnetic suspension subsystems have been proposed, and their performance and thrust characteristics have been obtained by experimental measurements and compared with theoretical results.
Abstract: High-temperature superconductors (HTSs) including HTS bulks and tapes have potential applications in linear motion drive and magnetic levitation/suspension systems generating substantial advantages over conventional ones. When an HTS linear motor is integrated with an HTS magnetic suspension subsystem, it can inherit both merits of HTS linear motion drive and HTS magnetic suspension simultaneously and can be applied into various fields, such as the maglev and electromagnetic aircraft launch systems (EMALSs). Based on different HTS aspects and arrangements, three modes of HTS linear synchronous motor (HTSLSM) integrated with HTS magnetic suspension subsystems have been proposed in this paper. To verify the modes for the design of a practical HTSLSM, the structural features of these systems are described, the magnetization characteristics to obtain HTS bulk magnets, the trapped-field attenuation characteristics of the HTS bulk magnet exposed to external traveling field, and the magnetic field distribution characteristics for different permanent-magnet guideways have been studied with experimental verification. Based on the study, a demonstration prototype of a single-sided HTSLSM integrated with HTS magnetic suspension subsystems has been developed. Its performance and thrust characteristics have been obtained by experimental measurements and compared with theoretical results. With regard to practical applications, two modes of double-sided HTSLSM integrated with HTS magnetic suspension subsystems have been designed for the maglev and EMALS, respectively, and then, the 2-D finite-element-analysis models for the HTSLSMs were built to analyze their performance characteristics. The comprehensive simulations and experimental results constitute a framework for the structural and electromagnetic design of the HTSLSM integrated with HTS magnetic suspension for practical applications.
TL;DR: The paper summarizes the conceptual design of this innovative limiter and reports in detail about the development of the super- conducting limiting elements, their integration into a cryostat and the design of the whole limiter including cooling and grid integration.
Abstract: In recent years many large scale demonstrators and prototypes of superconducting fault current limiters have been successfully developed and tested. Within the European Project ECCOFLOW (www.eccoflow.org), it is the first time that a resistive-type superconducting fault current limiter is developed for two different locations and that a permanent installation is foreseen. The limiter has a rating of 20 kV and 1 kA and will be tested in a busbar and transformer feeder application. The paper summarizes the conceptual design of this innovative limiter and reports in detail about the development of the super- conducting limiting elements, their integration into a cryostat and the design of the whole limiter including cooling and grid integration. As a main result it can be summarized that the ECCOFLOW limiter fulfills all requirements according to the two different specifications. Approximately 3 km of 12 mm wide YBCO tape will be used to realize a three phase system.
TL;DR: It is demonstrated that resistive SFCLs have an inverse current-time characteristic: They will quench (become resistive) in a time that inversely depends upon the initial fault current magnitude.
Abstract: Superconducting fault current limiters (SFCLs) may play an important role in power-dense electrical systems. Therefore, it is important to understand the dynamic characteristics of SFCLs. This will allow the behavior of multiple SFCLs in a system to be fully understood during faults and other transient conditions, which will consequently permit the coordination of the SFCL devices to ensure that only the device(s) closest to the fault location will operate. It will also allow SFCL behavior and impact to be taken into account when coordinating network protection systems. This paper demonstrates that resistive SFCLs have an inverse current-time characteristic: They will quench (become resistive) in a time that inversely depends upon the initial fault current magnitude. The timescales are shown to be much shorter than those typical of inverse overcurrent protection. A generic equation has been derived, which allows the quench time to be estimated for a given prospective fault current magnitude and initial superconductor temperature and for various superconducting device and material properties. This information will be of value to system designers in understanding the impact of SFCLs on network protection systems during faults and in planning the relative positions of multiple SFCLs.
TL;DR: The transient stability analysis of a power grid, which integrates both superconducting magnetic energy storage (SMES) and gridable vehicles (GVs), shows that both SMES and GVs can enhance transient stability of the power grid.
Abstract: This paper present the transient stability analysis of a power grid, which integrates both superconducting magnetic energy storage (SMES) and gridable vehicles (GVs). Also, vehicle-to-grid (V2G) operation is devised to control GVs to charge from or discharge to the grid. Simulations of various faults are carried out under different penetration proportions of SMES and V2G power. The results of load angle response and system voltage response are given to illustrate that both SMES and GVs can enhance transient stability of the power grid. Moreover, the simultaneous use of SMES and GVs can further improve the system dynamic performances.
TL;DR: In this paper, a 20 kW class HTS-ISM was designed and manufactured with DI-BSCCO wires and verified stable synchronous rotation at 1200 rpm, which is the world-first success of achieving the rotation at over 1000 rpm for fully superconducting motor.
Abstract: Our group has tried to introduce High Temperature Superconducting Technology to electric vehicle (EV) drive motor, and developed High Temperature Superconducting Induction-Synchronous Machine (HTS-ISM). In this paper, 20 kW class HTS-ISM were designed and manufactured with DI-BSCCO wires. First, we developed and tested partial superconducting HTS-ISM (HTS rotor windings with copper stator) for clarification of the performance. We could observe the efficiency at 92.3% even for the light load. Furthermore, we successfully fabricated and conducted no-load test for fully superconducting HTS-ISM. It was verified that stable synchronous rotation at 1200 rpm was succeeded, which is the world-first success of achieving the rotation at over 1000 rpm for fully superconducting motor. Our results are one of the big steps for realizing the HTS-EV.
TL;DR: In this paper, an advanced superconducting power conditioning system (ASPCS) composed of Electrolyzer-Hydrogen-FC and SMES cooled with liquid hydrogen from a station for vehicles is proposed.
Abstract: It is an urgent issue to reduce global carbon-dioxide in the world, and hence the renewable energy, that is environmentally friendly, should be supplied as a large amount of the electric power. Since installation of a large amount of the fluctuating renewable energy, such as wind turbine and photovoltaic, will cause the power utility network unstable, we propose an advanced superconducting power conditioning system (ASPCS) that is composed of Electrolyzer-Hydrogen-FC and SMES cooled with liquid hydrogen from a station for vehicles. The ASPCS has a function of compensating the fluctuating renewable energy with SMES that has quick response and large I/O power, and with that has moderate response and large capacity. The SMES is wound with superconductor with a critical temperature of 39 K from an economical point of view, because it is cooled with through a thermo-siphon system to keep safety against a flammable gas. The ASPCS effectively fulfills a power balance by applying a statistical prediction method of Kalman filter algorithm. The capacity of SMES is optimized by using the trend prediction for a number of wind power data. The overall electric efficiency of the ASPCS is evaluated for a typical wind generator.
TL;DR: The proposed fault-tolerant linear permanent-magnet motor offers high power density, high efficiency, high fault tolerance and low cost, suitable for maglev transportation applications.
Abstract: This paper proposes a new fault-tolerant linear permanent-magnet (PM) motor, termed as fault-tolerant primary PM (FT-PPM) motor. The proposed motor offers high power density, high efficiency, high fault tolerance and low cost, suitable for maglev transportation applications. Both PMs and windings are set at the steering device of the train, while the only iron stator is fixed between two rails along the whole line. Meanwhile, the new motor topology incorporates the concept of fault-tolerant teeth (FTT) to provide the desired decoupling among phases. The electromagnetic performances are analyzed such as field distributions, inductances, back-EMFs and thrust force. Moreover, by adopting assistant mover teeth, two methods are proposed to reduce the end-effect. Furthermore, the short-circuit current is analytically derived and predicted. The finite-element analysis (FEA) and transient co-simulated results are given for verification.
TL;DR: The Dresden High Magnetic Field Laboratory (HLD) achieved a magnetic field of 91.4 T in a 16 mm bore and it is available for users now as mentioned in this paper, which is the largest magnetic field ever achieved at the HLD.
Abstract: The Dresden High Magnetic Field Laboratory (HLD) is a pulsed-field user facility which offers to researches a variety of experimental techniques combined with non-destructive pulsed magnetic fields. Recently a new, 9.5 MJ dual-coil magnet has been commissioned. This magnet has achieved magnetic field of 91.4 T in a 16 mm bore and it is available for users now. In this paper, we report on some key upgrades in the magnet design which have led to breaking the 90 T limit at the HLD. Further possible design improvements are discussed. In addition, we share our operational experience obtained with the pulsed magnets.
TL;DR: In this paper, the authors describe the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent current effects in the coils, and discuss the mechanical design concepts based on separate collared coils.
Abstract: The LHC collimation upgrade foresees two additional collimators installed in the dispersion suppressor regions of points 2, 3 and 7. To obtain the necessary longitudinal space for the collimators, a solution based on an 11 T dipole as replacement of the 8.33 T LHC main dipoles is being considered. CERN and FNAL have started a joint development program to demonstrate the feasibility of technology for this purpose. The program started with the development and test of a 2-m-long single-aperture demonstrator magnet. The goal of the second phase is the design and construction of a series of 2-m-long twin-aperture demonstrator magnets with a nominal field of 11 T at 11.85 kA current. This paper describes the electromagnetic design and gives a forecast of the field quality including saturation of the iron yoke and persistent-current effects in the coils. The mechanical design concepts based on separate collared coils, assembled in a vertically split iron yoke are also discussed.
TL;DR: In this paper, a linear stator permanent magnet (PM) vernier high-temperature superconductor (HTS) machine is proposed for wave energy conversion, which adopts a double-sided design and inner-translator arrangement where the stator consists of two plane iron cores with salient teeth wound with 3-phase armature windings.
Abstract: In this paper, a new linear stator permanent magnet (PM) vernier high-temperature superconductor (HTS) machine is proposed for wave energy conversion. The machine adopts a double-sided design and inner-translator arrangement where the stator consists of two plane iron cores with salient teeth wound with 3-phase armature windings and PMs mounted on the surface of the stator teeth. While the translator is designed as an iron core with salient teeth on the two sides, the HTS bulks are inset between every two adjacent salient teeth to shield the flux leakage, thus improving the power density of the machine. Based on using the finite element analysis, the characteristics and performances of the proposed machine are assessed. Also, the proposed machine is quantitatively compared with the existing linear stator PM vernier machine. Hence, it validates that its performance, especially the power density, can be improved significantly.
TL;DR: In this paper, the four conductor samples composed of high performance strands manufactured by the bronze-route process for the ITER Central Solenoid (CS) conductor were fabricated and tested.
Abstract: Japan Atomic Energy Agency (JAEA) has fabricated and tested the four conductor samples composed of high performance strands manufactured by the bronze-route process for the ITER Central Solenoid (CS) conductor The current sharing temperature (Tcs) electrically assessed at 451 K and 1085 T along the cycling loading at 488 kA and 1085 T initially were 60 K and 61 K, and then 53 K and 55 K after 6000 cycles for the first SULTAN sample named JACS01, respectively As results of second SULTAN sample named JACS02, the Tcs values initially were 72 K and 68 K, and then 66 K and 61 K after 10000 cycles for each conductor, respectively The Tcs degradation was not saturated at the end of the test campaign From the destructive observation, the large bending at the low transverse loading side in the high field zone was observed The strand buckling and accumulating by slipping between the cable and the jacket are considered
TL;DR: The application of the superconducting fault current limiter (SFCL) with its proper resistance amplitude in a power distribution system with the DG could be confirmed to be contributed to the improvement of the protection coordination of the protective devices.
Abstract: The introduction of various dispersed generation (DG) in a power distribution system has caused the short-circuit current to increase, which can make the operation of the protective device deviate from its original set value. Especially, the increase of a short-circuit current in a power distribution system due to the increase of the DG is expected to be required for the related power utilities such as the circuit breaker to be replaced with a larger one. Among the countermeasures to solve the short-circuit problem in a power distribution system considering the increase of the DG, the superconducting fault current limiter (SFCL) has been noticed as one of the promising devices. In this paper, the protection coordination of the protective de- vices due to the application of a SFCL in a power distribution system where the DG was introduced into its bus line was analysed. The experimental circuit to simulate the DG and the protective de- vices was designed and realized by using power electronic switches. The short-circuit tests for the power distributed system assembled with the DG, the protective devices and the SFCL were carried out. Through the analysis on the results from the short-circuit tests, the application of the SFCL with its proper resistance amplitude in a power distribution system with the DG could be confirmed to be contributed to the improvement of the protection coordination of the protective devices.
TL;DR: In this article, the authors proposed a superconducting contactless power transfer (SUCPT) system, which is a combination of CPT technology with super-conducting receiver coils.
Abstract: This paper describes a operating characteristics of contactless power transfer (CPT) system from normal conducting coil to HTS coil based on the electromagnet resonance coupling. The basic principle is that two separate coils with same resonance frequency are possible to form a resonant system based on high frequency magnetic coupling and exchange energy in a high efficiency. The CPT technique with the electromagnetic resonance coupling has been expected as a useful option for contactless charge and storage devices. Since the CPT technology using normal conducting coils is sensitive to tune impedance matching, the transfer power efficiency is limited. From this reason, we proposed the combination CPT technology with superconducting receiver coils, it is called as, superconducting contactless power transfer (SUCPT). The SUCPT system can reduce joint loss of superconducting connection and increase the portability of the superconducting system. In this study, as a fundamental step, the optimal power transfer conditions needed to generate inductive power transfer between normal conducting coils and superconducting coil were experimentally examined. The power transfer profile for coupled resonance coils with high frequency power was investigated in order to minimize operating power.
TL;DR: In this article, two perpendicular Maxwell coils are presented to generate gradient magnetic field with theoretical analysis and two pairs of Helmholtz and Maxwell coils for the uniformities with considering coil thickness.
Abstract: The Helmholtz coils combined with the Maxwell coils can be used to generate the magnetic force for navigating a permanent magnet microrobot in the desired direction. To manipulate the microrobot effectively, two points should be noted: 1) High magnetic field uniformity of Helmholtz coils and magnetic field gradient uniformity of Maxwell coils; 2) High magnetic force with less current which reduces coil-heating and power consumption. Considering the two points, we evaluate and optimize the magnetic propulsion system in this paper. Firstly, two perpendicular Maxwell coils are presented to generate gradient magnetic field with theoretical analysis. The results indicate the two pairs of Maxwell coils system has better electrical properties than one pair. Secondly, we optimize the Helmholtz and Maxwell coils for the uniformities with considering coil thickness. The proposed system for the microrobot has higher navigation accuracy and good electrical properties.
TL;DR: In this article, the authors proposed a method which inserts the Cu tape between turn-turn winding in the HTS coil instead of electrical insulation to improve the self-protection ability of HTS coils.
Abstract: In the case of motors and generators, the benefits of using superconductors could be represented by the reduction of 50% in both losses and sizes compared to the conventional machines of the same rating. The high temperature superconducting (HTS) coils wound with HTS conductors have very low normal zone propagation velocity (NZPV) and complicated quench behaviors because the conductors have a low thermal conductivity and large specific heat. According to these reasons, in case of HTS coils and magnets, it is difficult to expect the self-protection like as low temperature superconducting (LTS) coils. In this paper, we suggest a method which inserts the Cu tape between turn-turn winding in the HTS coil instead of electrical insulation to improve the self-protection ability of HTS coils. Because the thermal and electrical contacts along the transverse direction are enhanced by inserted Cu tape instead of insulator and the whole thermal stability of HTS coils would be increased. To clarify the quench behavior of this suggested coil, we investigate the normal-zone propagation properties of the fabricated HTS pancake coils wound with 2G conductor and Cu tape under the cryocooled operation using GM cryocooler. The effects of inserted Cu tape and the improved the self-protection ability for the suggested HTS coil will be discussed.
TL;DR: In this paper, the authors simulate the behavior of resistive-type SCFCL modules based on MCP-BSCCO 2212 coils and show that short-circuit currents as high as 37 kApeak were limited to about 10% of their peak values in the first half cycle.
Abstract: Superconducting fault current limiters (SCFCLs) represent a promising solution to the problem of increasing short- circuit currents in the grid. The SCFCL is based on the fast transition from the superconducting state to the normal state, causing a sudden increase in the impedance of the network. In this paper, we simulate the behavior of resistive-type SCFCL modules. The SCFCL modules are based on MCP-BSCCO 2212 coils. The superconductor acts as a nonlinear resistance that varies with the current and the temperature. The behavior of the simulated curves is consistent with the experimental results. Short-circuit currents as high as 37 kApeak were limited to about 10% of their peak values in the first half cycle.
TL;DR: A No-Insulation winding technique that, based on experiment results of two test NbTi coils, promises to significantly improve stability and ease protection of high performance magnets; if applied to those used in marketplace MRI magnets, it may eradicate premature quenches that still afflict these magnets, though much less frequently than in the past.
Abstract: This paper describes and discusses a No-Insulation (NI) winding technique that, based on experiment results of two test NbTi coils, promises to significantly improve stability and ease protection of high performance magnets; if applied to those used in marketplace MRI magnets, it may eradicate premature quenches that still afflict these magnets, though much less frequently than in the past. The key idea is that a single turn in an NI winding can, upon a quench, share the copper stabilizers of neighboring turns through turn-to-turn contacts. To demonstrate the main features of the NI technique, two test coils (Φ30 mm) were wound with insulated (INS) and no-insulation (NI) NbTi wires, respectively. The results presented in this paper include: 1) charge-discharge test results and field analyses showing that the NI field performance is essentially identical to that of the INS coil except a charging delay; and 2) charging test results where coil voltages were measured during critical current tests to imply that the NI coil is charged more stably than its INS counterpart.
TL;DR: Experimental results of current-carrying capacities of a small test coil and joints made from MgB2 round wires, multifilament and monofilament (mono), manufactured by Hyper Tech Research, Inc are presented.
Abstract: Among key design and operation issues for MgB2 relevant to MRI magnets are: uniformity of current-carrying capacity over long lengths (>;2 km) of wire; and reliability of a splicing technique. This paper presents experimental results of current-carrying capacities of a small test coil and joints, both made from MgB2 round wires, multifilament and monofilament (mono), manufactured by Hyper Tech Research, Inc. The test coils were wound with 95-m long unreacted, C (carbon)-doped MgB2 multifilament wire, sintered at 700°C for 90 min. The critical currents were measured in the 4.2 K-15 K and 0 T-5 T ranges. We have modified our original splicing technique, proven successful with unreacted, un-doped multifilament wire sintered at 570°, and applied it to splice both un-doped and C-doped mono wires sintered at 700°C. Most consistently good results were obtained using the un-doped mono wires. Also presented are results of a small joint-coil-PCS assembly of mono wire, operated in persistent mode at 50 A at >;10 K.
TL;DR: The methods to maintain the protection operation of the protective devices due to the SFCL's application in a power distribution system were investigated through some case studies considering the time current curve (TCC) of the protection relay.
Abstract: In this paper, the application method of super- conducting fault current limiter (SFCL) for the protection coordination of the protective devices in a power distribution system was analyzed. The SFCL has been announced as better solution among many methods to limit a fault current effectively, which has continuously increased due to more complex network of a power system. However, the application of the SFCL in a power system affects the operation of the protection devices and the protection coordination, which requires the study on the protection coordination of the protective devices considering the application of the SFCL in a power distribution system. In this paper, the methods to maintain the protection operation of the protective devices due to the SFCL's application in a power distribution system were investigated through some case studies considering the time current curve (TCC) of the protection relay. The setting current and the lever among the setting parameters of the protective devices to keep the protection coordination in a power system with a SFCL were selected. Through the analysis on the TCC curves, the higher pick up current and the lower time lever values could be confirmed for protection coordination in case that the SFCL was introduced in the power system with the fixed impedance of the SFCL.
CERN1
TL;DR: In the EuCARD FP7 work-package 7, high field magnet (HFM) was developed for accelerator applications like HL-LHC and HE-lHC as discussed by the authors.
Abstract: In the EC FP7 program EuCARD (European Coordination for Accelerator Research & Development) the subject of work-package 7 is High Field Magnets. The aim of the HFM work-package is to develop technologies for magnets in the range 13 T-20 T for accelerator applications like HL-LHC and HE-LHC. The work-package foresees construction of a 13 T dipole with an aperture of 100 mm, an HTS dipole insert with ΔB = 6 T, an HTS current link and a helical undulator. The work-package has 12 European partners and the funding is shared between the EC and the partners. This contribution describes the aims of the work-package, the status of the work and the structure of the collaboration.