bluuebunny/crossref_metadata_2025_split huggingface dataset:
AC losses in superconducting coils
Authors: Akita Shirabe , Ishikawa Tadao , Tanaka Toshikatsu 
Published: July 2007

AbstractAC superconducting wire is being developed for such electrical equipment as superconducting transformers and superconducting generators. AC loss reduction is of primary concern in the development of such high‐efficiency equipment. In reducing ac losses, it is necessary to develop assessment methods for ac loss in test samples which have shapes similar to the end‐product equipment.This paper describes a least‐square calculation of ac losses of superconducting wire as a function of frequency and magnetic field strength measured in test coils.Two sample solenoid coils were made to test the influence of different capacities and winding methods on ac losses in ac superconducting coils with rated capacities of 500 kVA and 20 kVA, and impregnated (epoxy resin) and nonimpregnated windings.The ac losses in the superconducting coils were measured by a calorimetric method using the evaporating rates of liquid helium. Estimated ac losses in the superconducting wire of the two coils were compared with Joule losses of copper conductors at ambient temperature. As a result of this comparison, a low‐loss ac superconducting wire winding can be made for electrical equipment rather than employing conventional copper winding when used under low magnetic fields under 0.5 T.
Performance and conceptual design of superconducting magnet for disk MHD generator
Authors: Okamura Tetsuji , Kabashima Shigeharu , Shioda Susumu , Okuno Yoshihiro 
Published: July 2007

AbstractThis paper describes superconducting magnets coupled with two kinds of disk‐type MHD generators. One is coupled with a disk generator in the closed‐cycle MHD experimental facility FUJI‐1. The other is for a full‐scale disk MHD generator. These are split‐pair magnets.In the magnet for the FUJI‐1 facility, a unique structure which supports the coils against the electromagnetic force has been fabricated and the magnet has been operating stably. During MHD power generation experiments, an induced voltage across the terminals of the coil was measured. A magnitude of the Faraday current in the generator was calculated from this induced voltage.A possible construction of magnetics for a full‐scale disk MHD generator is indicated. It is suggested that a high performance of the generator (output power density of 0.3‐1 GW/m3) can be obtained with high magnetic field up to 10 T.
High‐frequency power transmission and selective distribution among loads by using distributed constant lines
Authors: Shimizu Toshihisa , Kimura Gunji , Shioya Mitsuo 
Published: July 2007

AbstractA widely used high‐frequency induction heating system usually consists of a high‐frequency power source and a load circuit to be heated. Since such a system can heat only one load circuit, heating two or more loads requires that other sytems be devised. Several problems result, including the need for many power sources, switches, and high‐frequency power transmission lines.To solve these problems, the authors propose a new system that can selectively supply two induction heating circuits with high‐frequency power. This system is composed of a high‐frequency voltage‐type inverter, a parallel resonant load circuit, and a series resonant load circuit, which are connected in series by distributed constant lines of specific length. Analysis of the operating characteristics of the system confirms that the system can supply the loads with high‐frequency power selectively and efficiently, with minimum interference between loads.The authors have compared theoretical simulation waveforms with actual waveforms observed on experimental equipment with output ratings of 1 to 2 MHz and 1 kW. As a result, experimental data agree well with theoretical data.This paper describes an operating principle and operating conditions of the system, and verifies that the theory we discuss is reasonable.
Evaluation methods on polymer materials for surface of outdoor insulators
Authors: Komatsubara Minoru , Ishii Masaru 
Published: July 2007

AbstractPerformance of nonceramic insulators is strongly related to hydrophobicity of the surface. Therefore, it is useful to evaluate the characteristics of the surface of organic insulating materials. To characterize the methods for the evaluation, some measurements were conducted on silicon rubber (SR), EPDM, PMMA and polyethylene (PE). The influence of irradiation with a mercury lamp was detected through measurements of contact angle, formation time of water film, and mass analysis of released gases under irradiation of electron beam.Measurement of the contact angle by using polar and nonpolar liquids revealed that silicon rubber (SR) was the most resistant against UV radiation. SR also showed recovery of hydrophobicity after UV irradiation. Measurement of the current flowing across the surface of materials exposed to artificial fog showed good agreement to the measurement of contact angle. Infrared absorption spectroscopic analysis enabled the intensity of oxidation of highly UV‐deteriorated organic insulating materials to be detected. Radicals on the surface of specimens were specified from the result of mass analysis of released gases. From these results, the nature of deterioration of organic insulating materials irradiated by UV is discussed.
A new test method for internal partial discharge resistance of insulating materials
Authors: Kako Yasuhiko , Watanabe Shigetaka , Higashimura Yutaka 
Published: July 2007

AbstractA new test method for internal PD resistance of insulating materials has been studied intensively by a task force at CIGRE for over ten years. Recently, Method II, which was developed by the authors, is now being studied as the international round robin test proposed by a domestic task force.This paper describes the new test method concretely and shows some typical test results. The test electrode system is characterized by adhesion of test specimen to the embedded sphere electrode, and it may be applicable to all sorts of insulating material for the internal PD resistance test under uniform partial discharges. The most important point of this method is to realize the complete adhesion by skillful techniques. It was ascertained that the spread of test data may depend only on the uniformity of materials by this method, and excellent life data can be obtained for some specific materials.
Improved combined cycle power plant operation design using optimization method
Authors: Fukushima Izu , Hino Shiro , Nakamoto Masahi , Takamiya Shigeru 
Published: July 2007

AbstractCombined cycle power plant takes advantage of the efficiency, fast startup, and small environmental impact. The operation design of this plant is required to make best use of this plant advantage. A large‐scale nonlinear mathematical model of this plant was developed to check the plant condition. This simulation model was combined with the optimization using Rosenbrock method. The operation design is optimized in two steps; [Step 1]: Some points of plant condition can be checked roughly; [Step 2]: This plant operation is optimized to design using Rosenbrock method. This optimization is applied to design the combined cycle power plant operation. It is confirmed that this method is effective for the design of plant operation. From this study, plant operation can be designed with this optimization to make best use of this plant advantage. Then operation design point is decided using the optimization method on some evaluation instead of heuristic method.
Basic characteristics of high‐Tc superconductor as a current‐limiting element
Authors: Nakamura Koichi , Ito Yasukazu , Kawashima Takao 
Published: July 2007

AbstractThis paper shows the basic characteristics of a current‐limiting element for the power system using y‐type high‐Tc superconductor. (1) A YBa2Cu3Ox‐type superconductor was produced. Its size was 4.7 × 1.5 × 47 mm. (2) Current I and voltage V were measured under the low temperature of 50 to 100 K. (3) The flow resistance and the resistance of the element were defined and evaluated from the I ‐ V characteristics obtained under the conditions of lower temperature than the critical value Tc, and larger current density than the critical value Jc. (4) The resistance value change due to temperature rise also was evaluated under the larger current than the critical current. (5) A schematic calculation was tried for practical use in some system condition.
Surge analysis of the tank of a gas‐insulated line using lumped constant circuits
Authors: Nagaoka Naoto , Ueno Shintaro , Sugahara Keishi 
Published: July 2007

AbstractSurge voltages evaluated by a digital analysis method, for example, electromagnetic transients program (EMTP) and by an analog analysis method (transient network analyzer: TNA) are compared with experimental results on a scaled model of a gas insulated line. From the results, it is confirmed that the analog analysis method has a satisfactory accuracy and its computing speed is quite high. The error caused by the lumped element modeling of the gas insulated line is comparatively small, and the line is not necessary to be treated as a distributed parameter line. The lumped element model is advantageous to understand the mechanism of the transient characteristic of the induced transient voltage. A simple equivalent circuit of the gas insulated line is proposed and its accuracy is confirmed by a comparison with the calculated result obtained by an accurate line method. The transient overvoltages of the tank and across the insulated flange can be analytically calculated using the equivalent model.
Performance analysis and circuit design of high‐frequency resonant inverter using a single reverse‐conducting device
Authors: Ogiwara Hiroyuki , Nakaoka Mutsuo 
Published: July 2007

AbstractThis paper is concerned mainly with a performance analysis and a design method of a newly developed zero‐current switching quasi‐resonant high‐frequency inverter (ZCS‐QRI) using a single reverse‐blocking power device (high‐frequency GATT). As a matter of fact, GATT is replaced by the latest MOS‐gate power semiconductor devices, MOSFET, IGBT, MCT and Bi‐MOS · GTO thyristor.The frequency‐modulated single‐ended inverter circuit, which incorporates an auxiliary diode and large reactor cascade branch in parallel with a resonant capacitor connected into the transformer‐link series‐resonant tuned tank load circuit can stably and efficiently operate in the frequency range from 20 kHz up to 50 kHz or so. It is proved that the ZCS‐QRI is more suitable for several kilowatt induction‐heating and melting power supplies and high‐intensity ultrasonic generator, and switched‐mode dc‐dc converters.This simple high‐frequency ZCS‐QRI for induction‐heating load model is analyzed introducing normalized resonant and load circuit parameters and control variable on the basis of computer‐aided simulation. The load and frequency regulation characteristics of ZCS‐QRI and ZCS operating range are illustrated with a normalized expression in addition to voltage and current peak values and stresses of the power semiconductor device. The practical computer‐aided design procedure using the inverter characteristics in steady‐state expressed in the normalized technique is demonstrated and discussed including a design example. The simulation results of ZCS‐QRI are illustrated and compared with the experimental results in trial‐produced breadboard.
Optimization of 3‐D nonlinear magnetic circuit by using the magnetization integral equation method
Authors: Takahashi Norio , Nakata Takayoshi , Uchiyama Noriyuki 
Published: July 2007

AbstractTo design optimal electrical machines, it is necessary to develop an optimal design method for determining the shapes, sizes, positions of the cores, permanent magnets and windings which produce such specified values as flux distributions and torques.In this paper, a design method for determining the optimal sizes of cores taking into account the nonlinearity of the core has been developed by using the nonlinear programming method and the magnetization integral equation method. The pole shape of an electromagnet which produces the uniform flux distribution is determined by using the design method for determining the optimal sizes of cores. The effectiveness of the method is shown by designing the pole piece of the permanent magnet‐type MRI device.
PI architecture functionally distributed system for power network supervisory control
Authors: Kunugi Masahiko , Yohda Masahiko , Tamura Shinsuke , Kishida Yukio , Hayashi Tatsuo , Hasegawa Tsuguo 
Published: July 2007

AbstractIn recent years, the sizes of Energy Management Systems (EMS) and Supervisory Control and Data Acquisition (SCADA) systems have grown to huge proportions for two reasons:

The power systems to which they are applied have grown in size and complexity; and
Their own functions have become more diverse and sophisticated.
This raises the following problems: degradation of response time; decreased reliability; limited expandability; less maintainability; and increased costs.A functionally distributed system that is characterized by parallel processing and independent subsystems (parallel‐independent architecture) will solve these problems.The system is comprised of a group of functional units, each of which runs in parallel, independently and asynchronously. Copies of some programs and power system status data are stored in the relevant functional units, and data‐driven architecture is adopted, which eliminates the need for a centralized control mechanism.The feasibility of a functionally distributed system was tested through construction of a prototype. The results were satisfactory.
A feasibility study of a direct‐mapping parallel processing method to solve linear equations in load‐flow calculation
Authors: Inayoshi Hiroaki , Homma Takuya , Ohsawa Yasuharu 
Published: July 2007

AbstractWith the growing size and complexity of power systems, system analysis—such as transients calculation—takes much time. Hence, fast calculation methods are required. Although parallel processing is a hopeful method, there have been difficulties in the parallel solution of linear equations which appear in power‐flow calculations by the Newton‐Raphson method.This paper aims at the fast calculation of the power‐flow problem by means of parallel processing. In order to improve the suitability to the parallel solution of the differential equation in transients calculation, we assume the use of a direct‐mapping parallel processing machine to map directly the network of a power system onto a network of processors. Under this assumption, we propose a new parallel‐processing‐oriented method in which the linear equation is solved by linear iterations between nodes with Aitken acceleration. We simulate the method on three model power systems and compare this Parallel Iterative Method (PIN) with a Parallel Direct Method (PDM) which uses the banded matrix according to the number of operations required. As a result, we can expect that PIM may solve linear equations faster than PDM with m processors, although the PIM might be inferior to the PDM with m × m processors, where m denotes the half‐band width of the banded matrix.
New power consolidation‐inversion‐control system for faraday MHD generator
Authors: Inui Yoshitaka , Kato Mitsuhide , Morimoto Kenji , Ishikawa Motoo , Umoto Juro 
Published: July 2007

AbstractThe authors propose a new power consolidation‐inversion‐control system for the Faraday MHD generator using the voltage source PWM inverters. The dc output power for each electrodes pair of the MHD generator is at first inverted into three‐phase ac power by a voltage source PWM inverter, and then the ac powers are consolidated by transformers. The proposed system does not need such expensive equipment as an ac filter or phase modifier and can independently and simultaneously control the active and reactive powers provided to the electric power system. Numerical simulations of the whole system, including the Faraday MHD generator, the proposed power consolidation‐inversion‐control system, and the electric power system, show that the proposed system can stably and steadily transmit and control the electric power from the MHD generator to the electric power system. It is also confirmed that the proposed system can independently and simultaneously control the active and reactive powers and can be used as a fast power controller.
High‐field conduction and carrier traps in polyethylene copolymerized with various monomers
Authors: Ishino Iwao , Hikita Masayuki , Suzuoki Yasuo , Mizutani Teruyoshi , Ieda Masayuki 
Published: July 2007

AbstractThe electrical breakdown and electrical conduction of ethylene copolymers have been studied. The electric strength of ethylene copolymers containing an optimum content of halogen moieties such as bromophenyl and fluoroethylene groups was found to be higher than that of LDPE over the wide temperature range from −196°C to 90°C. Also, conduction currents in the copolymers were suppressed at high electric fields. X‐ray‐induced thermally stimulated currents (TSC) revealed that halogen comonomers act as carrier traps with a depth of about 0.4 eV. Consequently, the introduction of comonomer‐containing halogen groups into polyethylene suppresses electron acceleration as a result of an increase in trapping and scattering of conduction electrons. This leads to an increase in electric strength which is determined by the electron avalanche breakdown.
Study of space‐charge characteristics in polyethylene for power cable insulation by laser‐induced pressure‐pulse technique
Authors: Yoshifuji Naohisa , Suzuoki Yasuo , Han Sangok , Matsukawa Youji , Furuta Tetsuya , Yamada Hironori , Mizutani Teruyoshi , Ieda Masayuki 
Published: July 2007

AbstractBy utilizing the laser induced pressure‐pulse (LIPP) technique, the behavior of space charge in low‐density polyethylene (LDPE) and crosslinked polyethylene (XLPE) films in contact with metal or carbon‐loaded semiconducting layers was studied quantitatively to clarify the space‐charge characteristics in power cables.Negative heterospace charge near the anode and positive space charge in the bulk were observed in unoxidized LDPE under the fields above 120 kV/mm. The amount of negative space charge increased with applied field, while positive space charge in the bulk disappeared with increasing applied field. This indicates that electron injection and ionization are enhanced by applied field.Prominent negative homospace charge was formed near the cathode in oxidized LDPE, which indicates that oxidation enhanced electron injection. The depth of charge centroid from the cathode became larger with increasing temperature. This indicates that the effective electron mobility increases with temperature.Negative space charge also was formed in the bulk in XLPE films with metal electrodes, which indicates that crosslinking enhanced electron injection. XLPE films with a carbon‐loaded semiconducting layer showed both negative and positive homospace charges near the semiconducting layers, which indicates that both electrons and holes were injected from the semiconducting layer.
Development of a new detection method of partial discharge for EHV long‐distance active cable line
Authors: Katsuta Ginzo , Toya Atsushi , Endoh Takeshi , Suzuki Hiroshi , Sekii Yasuo 
Published: July 2007

AbstractA new method was used to measure the characteristics of partial discharge (PD) for an active 9.5‐km long‐distance 275‐kV XLPE cable line with insulating joints. It was found that the detection of PD and the calibration of detection sensitivity were carried out safely and easily. The proposed method includes:

detection of PDs and injection of calibration pulses using two pairs of metal electrodes placed on PVC jackets with anti‐corrosion layers separated by a joint sleeve sectionalizing insulator;
measurement of detection sensitivity with distance using calibration pulses injected from an adjacent insulating joint;
detection of PDs with a high S/N ratio measured at a frequency corresponding to the lowest noise level; and
usage of rf cores attached at cross‐bonding leads and wires for sheath current limiters to reduce the crosstalk of signal and noise through these lines at insulating joints.
Using a combination of these techniques, the highest detection sensitivity was 1 pC in the vicinity of an insulating joint, and 15 pC at 617 m from the adjacent joint. The sensitivity obtained by the conventional PD measurement using a low‐frequency method was at most 1000 pC.
Piezoelectric ceramics of (Bi1/2Na1/2)TiO3‐PbTiO3‐BaTiO3 system
Authors: Takenaka Tadashi , Naitou Yuichi , Sakata Koichiro 
Published: July 2007

AbstractPiezoelectric and ferroelectric properties of bismuth sodium titanate, (Bi1/2Na1/2)TiO3(BNT)‐based solid solution, that is, (Bi1/2Na1/2)(1‐x)(Pba Bab)xTiO3(a + b = 1) [BNPB(100x‐100a/100b)], are studied from the viewpoint of a new group of lead‐free or low‐lead content piezo‐electric ceramics with a rhombohedral(Fa‐tetragonal (Fβ) morphotropic phase boundary (MPB). It is evident that the MPB seems to be remarkably efficacious in promoting piezoelectric and pyroelectric activities by electrical poling.X‐ray diffraction data, dielectric properties and D‐E hysteresis loops show that the MPB exist near (Bi1/2Na1/2)TiO3[BNT] at x = 0.13–0.14, 0.08–0.09 and 0.06–0.07 in the case of b = 0, b = 0.5 and b = 1, respectively. BNPB ceramics are superior for piezoelectric ceramics in high‐frequency ultrasonic uses, or special piezoelectric actuator materials with a lower free permittivity ε33Tε0, and a high electromechanical coupling factor k33, along with a high mechanical strength.
Equivalent circuit analysis for magnetostatic wave devices
Authors: Koike Takuro , Ohba Masafumi 
Published: July 2007

AbstractMagnetostatic wave (MSW) devices are potentially very promising for carrying out signal processing directly at microwave frequencies, and recently have been receiving much attention. Although the development of a general design theory is essential for significant progress in the signal processing capabilities of the MSW devices, relatively few design theories have been discussed in the past.This paper extends and improves the general equivalent circuit approach to the magnetostatic wave devices proposed and discussed earlier. Based on the definitions of the purely magnetostatic terminal parameters and the magnetostatic characteristic impedance, the electromagnetostatic energy conversion is discussed and the appropriate general equivalent circuit models for the MSW devices are developed. Calculated insertion losses for various MSW devices are in excellent agreement with experimental results.
On the design of a single‐sided linear induction motor for urban transit
Authors: Nonaka Sakutaro , Higuchi Tsuyoshi 
Published: July 2007

AbstractSingle‐sided linear induction motor (SLIM) propulsion and wheel‐on‐rail support and guidance for urban transit has been developed in Canada and Japan. The maximum speed for urban transit is about 70 km/h, with the trains repeatedly performing powering, coasting, and braking operations within relatively short distances between stations. In the design of SLIM's operating under such conditions, we must take into account energy consumption as well as motor weight, input KVA, and performance characteristics. In this paper, we conduct a theoretical examination of such a SLIM design, estimating its performance characteristics in using space harmonic analysis. Energy consumption is reduced by decreasing the mechanical clearance. The flux density, then, should be a low value of from 0.5 T to 0.6 T. A motor length of from 2 to 2.5 m and pole pitch of about 300 mm are advisable.