bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deadbeat flux level control of direct‐field‐oriented induction motor
Authors: Huang Lipei , Tadokoro Yasuki , Tsukakoshi Masahiko , Matsuse Kouki 
Published: July 2007

AbstractA method for the deadbeat flux level control of a direct‐field‐oriented induction motor with position control loop has been developed that employs an adaptive rotor flux observer. The observer is a full‐order type and is used not only in the direct‐field‐oriented controller, but also to identify stator and rotor resistances of the motor. The observer reduces the sensitivity of a deadbeat controller to fluctuations in the motor parameters. The main advantage of this method is that it improves the efficiency of an induction motor without sacrificing dynamic performance.This paper describes the method as well as the fundamental characteristics of the system derived from experimental and simulation results.
Development of high‐Jc NbTi multifilamentary superconducting wire with Nb artificial pins for AC applications
Authors: Miura Osuke , Inoue Itaru , Matsumoto Kaname , Tanaka Yasuzo 
Published: July 2007

AbstractHigh critical current densities of 1.61 × 1010 A/m2 at 1 T, 6.1 × 109 A/m2 at 3 T and 2.9 × 109 A/m2 at 5 T were achieved by controlling the distribution of Nb artificial pins in NbTi multifilamentary superconducting wires for ac applications. The critical current densities attained are over two times higher than those of conventional ac superconducting wires. This increase can be attributed to the shift of the peak of pinning force density to higher magnetic field by optimizing the pinning parameters.The benefits of increasing critical current densities for ac applications are demonstrated. A 2.5 T/100 kVA ac superconducting magnet was designed and made by using high Jc wire with controlled distribution of Nb artificial pins. Compared with conventional ac superconducting magnets, the new magnet exhibits a drastic decrease in size as well as in ac losses.
Dielectric properties of mica‐alumina combined insulation at high temperatures
Authors: Ishida M. , Ikeda Y. , Naohara N. , Mitsui H. , Kumazawa R. , Kuroki T. 
Published: July 2007

AbstractDevelopment of sodium‐immersed‐type Electromagnetic Pumps (EMP) is expected to improve reliability, safety, maintainability, and construction cost of the Fast Breeder Reactor (FBR) compared with the conventional mechanical pumps. To realize the EMP, establishment of a high‐temperature‐resistant electrical insulating system is indispensable.A mica‐alumina combination is selected for the insulating system at temperatures higher than 500°C. Using this insulating system, an aging pretest was performed. The aging condition was to apply 1.5‐kV ac voltage in the nitrogen atmosphere at 550°C for 4000 hours. The dielectric properties before and after the aging were measured to understand the tendency of temporal change in the aging.In this result, the dielectric performance after aging was improved compared with the initial performance. The curious phenomenon was clarified to be caused by a decrease of organic component in the insulation, which remained due to incomplete burning. Also, the possibility of thermal runaway was considered to be higher as a dielectric breakdown mechanism.
An evaluation method for power transfer capability enhanced by lightning countermeasures
Authors: Takahashi Kazuhiro , Inoue Atsuyuki , Tanaka Kazuyuki 
Published: July 2007

AbstractVarious countermeasures are taken against lightning faults in power transmission lines to decrease their occurrence and improve transmission reliability. However, how much they enhance the power transfer capability has not yet been quantitatively evaluated. The conventional deterministic approach, which is widely used in power system planning methodology, is inadequate to deal with this issue.This paper proposes a new method for numerically defining the power transfer capability enhanced by countermeasures against lightning. The proposed method is based on a probabilistic approach in which several fault patterns are taken into consideration with their occurrence frequency and maximum transferable power. This paper also gives an example application of the proposed method to a model trunk transmission system. The effect of a third overhead ground wire on the increase of transfer capability of a 500 kV transmission line has been quantitatively evaluated.
Experimental study of LIM‐driven, attraction‐type magnetically levitated carrying system
Authors: Hikihara Takashi , Hirane Yoshihisa , Uejyou Takeshi 
Published: July 2007

AbstractRecently, many kinds of magnetic levitation systems have been proposed and developed for use in factory automation systems. This progress in the development depends on the appearance of new types of permanent magnets and new control theories. On the other hand, some systems have simple structures in which couples roles are given for both levitation and conveyance. As for these systems, however, many trials are needed to establish the system configurations and the control theory. The authors have developed a new magnetically levitated carrying system driven by LIM (linear‐induction motor). The system can be completely detached from a guideway both in mechanical and electrical meanings.In this paper, the experimental results, especially the driving characteristics of a vehicle without any contacts to the LIM guideway, are discussed.
Inertia‐lowering control of induction motor
Authors: Terashima Masayuki , Ashikaga Tadashi , Kataoka Yasuo , Nakano Yoshinori , Nomura Masakatu , Hara Kiyoshi 
Published: July 2007

AbstractThere are many requests for selecting freely the moment of inertia, even though the moment of inertia is determined by the materials, structure, shape, and size of the motors. From the standpoint of control, reducing the moment of inertia will make it possible to construct well‐controlled drive systems and expand the applications in which a motor may be used to replace another nonelectric machine. An “inertia‐lowering control” system has been developed that uses disturbance observer to reduce inertia.To realize this control system with vector‐controlled induction motors, the equations and machine constants needed for designing the systems have been clarified. A digital signal processor and a microprocessor were adopted for induction motor control, and good results were obtained through the experiments.
AC V‐t and impulse V‐N characteristics of shell‐form transformer insulation model
Authors: Okabe Shigemitsu , Ohno Takahiro , Zaima Eiichi , Kishi Akio , Aono Kazuaki , Hosokawa Noboru 
Published: July 2007

AbstractTo evaluate an appropriate level of ac test voltage for 1000‐kV transformers, it is necessary to make an accurate estimation of ac V‐t characteristics. For the level of impulse test voltage, V‐N characteristics are important to evaluate effects of impulse stress repetition. Since both of the characteristics are dependent on insulation structures and manufacturing processes of transformers, it is important to make accurate simulations on transformer insulation for reliable insulation data.To obtain some of the basic data for 1000‐kV transformer test levels, long‐time ac V‐t tests and impulse V‐N tests of up to 1000 times voltage application were carried out on an insulation model simulating fundamental structure of shell‐form transformers. The model is composed of a parallel electrodes system with a compound structure of pressboard barrier and oil gap.The tests showed the following characteristics: ac V‐t characteristics of up to several ten days could be described by two lines, each representing short‐time and long‐time characteristics. V‐N characteristics of lightning and switching impulse were expressed by relatively flat lines, which showed a decrease in breakdown voltage by less than 10 percent after 1000 times impulse application.
An application of artificial neural networks to maintenance scheduling covering of thermal units over several consecutive years
Authors: Sasaki Hiroshi , Takiuchi Yoshiyuki , Kukobawa Junji 
Published: July 2007

AbstractThermal units must be maintained periodically as prescribed by the electric utility industry law. As time to execute maintenance works increases with thermal unit capacity, maintenance scheduling has a great influence on the reliability and economy of a power system. In the recent amendment in the law, three inspection rankings have been introduced and scheduling over several consecutive years becomes mandatory, thus making maintenance scheduling extremely difficult. Reflecting a recent stringent supply capability, the emphasis is laid on security rather than a minimum operating cost, having been the primary objective in determining the schedules. Therefore, this study aims to level the spinning reserve at each period under study in the maintenance scheduling while taking into consideration all the amendments in the law. Although rigorous methods such as integer programming and branch and bound method can solve small scale problems, large size problems are beyond these techniques due to an exponential explosion in the number of possible combinations.The prime objective of this paper is to investigate the capability of the Hopfield neural network (HNN) in solving the newly formulated maintenance scheduling problem. The scheduling problem has been mapped on the HNN with slight problem relaxations to facilitate the implementation. A small scheduling problem that determines the maintenance schedules of 3 generators over 3 years (divided to 78 periods) has been solved by the neural network simulator. It has been made clear from simulation results that the proposed approach is very promising in handling a complicated combinatorial optimization problem.
Method of detecting the index position of a spindle motor for slim flexible disk drive
Authors: Imai Yasuaki 
Published: July 2007

AbstractA slim flexible disk drive, which could be mounted on a hand‐held personal computer, is now under intensive study in Japan. The spindle motor for the flexible disk drive has an index‐position detecting means, an index magnet attached to the outer wall of the periphery of the rotor yoke, and a magnetic sensor which detects the magnetic flux from the index magnet. As a result, spaces for providing the index magnet and the magnetic sensor prevent the motor from being made smaller in size and reduced in thickness.This paper describes the method for detecting the index position of a spindle motor without both the index magnet and the magnetic sensor. This method detects an index position per rotation from two different kinds of frequency generating signals (main FG and sub FG) through an index‐detecting circuit. The thin spindle motor to which this index‐detecting method is applied, performed a smaller degree of rotational speed variation compared with another well‐known one without both the index magnet and the magnetic sensor. This index‐detecting method is most suitable for a less‐inertia‐thin spindle motor, and is easy to assemble.
Trajectory control of controlled‐PM linear synchronous motor magnetic levitation vehicle—FEM dynamics simulations and experiments in mass‐reduced‐control mode
Authors: Yoshida Kinjiro , Takami Hiroshi , Yokota Dai , Nishitani Mitsumasa , Sonoda Akihiro 
Published: July 2007

AbstractA novel magnetic levitation train system can be constructed by using a long‐stator controlled‐PM linear synchronous motor having propulsion and attractive‐mode levitation functions and minimum loss. Realizing this system requires simplifying manufacture of the long‐stator guideway. In the long‐stator on the ground, semiclosed large slots are adapted and designed for one‐turn coils of a waveform to be easily installed. The large slots cause the PM LSM detent forces to give strong influences on dynamic operations of the running vehicle. A two‐dimensional FEM used for the dynamics simulations is capable of precisely analyzing the detent forces produced between the stator teeth and the PMs.This paper presents FEM dynamics simulations and experiments in mass‐reduced‐control mode of a 1/2 scale model magnetic levitation vehicle supported by small rubber rollers. The simulation model developed here includes the vehicle speed performance, position sensors and drag force due to friction between rubber roller and rail. The detent force problem in propulsion motion is successfully solved by adapting the feedback control of the vehicle propulsion based on the I10‐controlled method. The trajectory control is thus accomplished for the vehicle to follow speed and position patterns. The dynamics simulations are verified from the experiments. The simulation program proposed here enables us to investigate the magnetic levitation train system, including LSM design and vehicle dynamic operations.
Magnetic characteristics of oxide superconductors for the application of running systems with magnetic levitation
Authors: Suzuki Haruhiko , Yogiashi Kozo , Kusano Koichi , Takashige Masaaki 
Published: July 2007

AbstractA model vehicle is constructed which runs without contact to its magnetic rail using oxide superconductors. This paper describes the forces acting between the superconductor and the rail for such a purpose. The attractive and repulsive forces were measured at 77 K as a function of distance between the superconducting pellet and the magnetic rail. As suprconducting pellets, three kinds of materials, i.e., MPMG‐Y123, BiPb2223, and Hg1223, were investigated for three kinds of permanent magnets, i.e., Nd‐Fe‐B, Sm‐Co and ferrite.
Quantitative analysis of swarming pulsive microdischarges by using very low frequency voltage application
Authors: Ishida Takahiro , Nagao Masayuki , Kosaki Masamitsu 
Published: July 2007

AbstractPartial discharge (PD) degradation phenomena is one of the most important factors to decide the performance and the lifetime of the high voltage apparatus. During PD degradation tests of an epoxy specimen with an internal void, PD often change to a large number of very small PD known as swarming pulsive microdischarges (SPMD). Because the appearance of SPMD is concerned with the degradation of the insulating materials, the insulation diagnosis with the detection of SPMD becomes possible. However, SPMD cannot be detected with the conventional PD Detector because the PD magnitude of SPMD is too small. The computer‐aided partial discharge analyzing system (CAPDAS) has been developed to detect and analyze the SPMD. Furthermore, a new PD parameter, the SPMD ratio has been introduced for quantitative analysis of SPMD. In this paper, the time variation of SPMD characteristics of a CIGRE Method‐II specimen are investigated by using the CAPDAS. Further, the effect of the frequency of the applied voltage on SPMD is also investigated at 60 Hz and a very low frequency of 0.1 Hz. As a result, the comparison of PD magnitudes measured at 60 Hz with those at 0.1 Hz enables a quantitative analysis of SPMD characteristics to be possible by using only the conventional PD detector.
Fast calculation using parallel processing and pipeline processing in power system analysis
Authors: Oda Yoshifumi , Oyama Tsutomu 
Published: July 2007

AbstractThis paper presents an application of parallel processing and pipeline processing to power system analysis. The system matrix is transformed to a bordered block diagonal form (BBDF) matrix for effective utilization of the processors. After LU factorization, subnetworks organize sparse matrices and the boundary network organizes a full matrix. First, a parallel processing technique is used to calculate subnetworks. Then, as pipeline processing is applied, inverse matrix of the boundary network is multiplied. The proposed method is made operational on a parallel computing system including a pipeline processor. A consideration on the transient stability analysis using the proposed method also is presented at the end of this paper.
Commercialization of an extra high‐voltage nonflammable transformer
Authors: Mizuno Kazuhiro , Sakamoto Takeshi , Endo Kaoru , Fujita Hiroyuki , Hiraishi Kiyoto 
Published: July 2007

AbstractA perfluorocarbon (PFC)‐immersed 275‐kV transformer with compressed SF6, gas has been developed. This paper describes the basic cooling and insulation characteristics of PFC, the ac partial discharge voltage, and the aging of PFC‐immersed insulation. The results demonstrate that a prototype 275‐kV 100‐MVA three‐phase transformer can be operated without any difficulties for an extended period of overvoltage. This prototype has an ac partial discharge initiation strength which is 1.5 times that of the ac test voltage and a lightning impulse breakdown strength which is 1.5 times that of the test voltage. A 275‐kV 250‐MVA three‐phase transformer was built and is being operated at the Abe substation of Chubu Electric Power Co., Inc. The transformer has been operating satisfactorily.
Control system design for an ideal transient control performance—proposal of simulator‐based foresight control
Authors: Uchida Motomiki , Nakano Kazushi 
Published: July 2007

AbstractA new concept to achieve an ideal transient control performance is described. It is also possible to examine control performance on the frequency domain. Generally speaking, better control performance will be realized by using more exact information on the plant. A simulator should be built that has both correct initial values of state variables and parameters on dominant parts of the plant. The internal states of the simulator are used to represent the internal states of the plant, and control input is synthesized with the internal states of the simulator and the plant output. Using information on the simulator allows an ideal control performance at a dominant frequency area to be obtained in spite of the existence of unmodeled dynamics at a higher frequency domain. This control system is called simulator‐based foresight control (SFC), and is available for both nonlinear and timevarying plants.
Basic characteristics of five‐phase cylindrical linear pulse motors
Authors: Dohmeki Hideo , Satomi Hirofumi , Iwasa Takao 
Published: July 2007

AbstractA cylindrical linear pulse motor (CLPM) of a new construction is proposed in this paper. The conventional CLPM, which has a permanent magnet between A‐phase and B‐phase stators, has a problem: thrust unbalance occurs because the magnetic flux of the outer poles is longer than that of the inner poles. This paper proposes a CLPM of completely new construction, in which the field magnetic flux and the armature magnetic flux perpendicularly intersect each other as a result of a restructured magnetic circuit. This new CLPM has the same magnetic field as the stepping motor, and has the distinctive characteristic of being available in a multiphase design, as well as the conventional two‐phase design. A five‐phase 10‐pole CLPM was experimentally manufactured and the static thrust was measured to identify its basic characteristics. The experiment confirmed the theory that the torque did not differ from phase to phase and that controllability equal to that of the stepping motor was obtainable. The CLPM proposed here is effective as an alternate linear electromagnetic actuator for electrical servos of air actuators (such as air cylinders).
Space charge behavior in an antistatic polymer including polymer solid electrolyte
Authors: Fukunaga Kaori , Maeno Takashi 
Published: July 2007

AbstractA polymer dielectric material tends to be easily charged and may cause an electrostatic discharge, due to the serious problems that result when consequent electromagnetic noise damages the electronic circuits in various kinds of apparatus. The antistatic polymers that have been developed to prevent electrostatic discharge contain polymer solid electrolytes so that space charge originally exists inside them. The mechanism of the antistatic discharge effect of the polymer has been investigated by measuring the space charge distribution using the high‐resolution pulsed‐electroacoustic method. The experimental results suggest that the internal space charge of the polymer accumulates at the surface and forms heterocharge distribution at the interface between the electrodes and the specimen. Thus, internal space charge compensates the applied electric field, resulting in preventing the increase of the surface potential. In addition, internal space charge behavior relates to the dispersion condition of the polymer solid electrolyte that depends on the quantity of the electrolytes and the specimen procedures.
Development of a distribution line state monitoring system
Authors: Fudou Hiroyuki , Kawasaki Yukio , Egawa Susumu , Shinozaki Kouichi , Abe Norio , Toda Kazuro 
Published: July 2007

AbstractTo improve the electricity service reliability, a distribution line state monitoring system has been developed. It is composed of a central control unit, remote control switches, the slave unit and monitoring sensors. The first system employed fiber‐optic voltage and a current sensor. The latest system employs a unique form of cost reduction, with no voltage sensors incorporated. This system can detect the grounding direction by the information of the phase difference between the line‐to‐line voltage and I0 provided by the monitoring sensor, and grounded line information (64ϕ) from the substation. Installation of the system has been underway since 1992.
Suppression of lightning‐induced overvoltages by distribution line surge arresters
Authors: Fujiwara Nobuyuki , Yoneyama Tsukasa , Hamada Yoshiyuki , Yokota Tsutomu , Asakawa Akira , Shimomura Tetsuro , Yamaoka Koichi , Ishibe Shinji 
Published: July 2007

AbstractThe primary aim of surge arresters in power distribution lines is to protect lines and equipment from the voltage induced by nearby lightning strokes. To further improve power systems, methods to protect distribution lines against direct lightning strokes are still needed. An effective measure against direct lightning strokes is to increase the number of arresters. However, if the surge current is too large, some surge arresters absorb energy in excess of their capability and may break; this leads to a line fault. To evaluate the protective effect of the surge arresters against direct lightning strokes to overhead ground wire, the authors measured both the voltage across the surge arresters and the energy absorbed by them using a full‐scale model line and a 12 MV impulse generator. The results were compared with simulation results by EMTP. There have been no previous studies making a comparison of this kind.
Development of negotiation expert system for subtransmission system planning
Authors: Aihara Yasuhiko , Hayashi Yasuhiro , Terashima Takayuki , Takemoto Ikuko , Iwamoto Shin'Ichi 
Published: July 2007

AbstractRecently, the task of planning in power systems is becoming a very complicated process for utility planners. This kind of planning has many objectives to accomplish. This paper employs the negotiation algorithm, which was proposed by the Chen‐Ching Liu group for subtransmission power system planning to create a plan having many objectives. First, the goal‐decision network (GDN) is constructed to model this planning problem, and the negotiation algorithm is applied to utilize both subtransmission system planning GDN, which attempts to capture its knowledge, and negotiation operators, which search for the most feasible and promising decisions in this planning GDN. Finally, the negotiation expert system is demonstrated for the subtransmission system planning using a real system.