bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flux synthesizing linear induction motor with super multiphase switching
Authors: Koseki Takafumi , Morizane Toshimitsu , Masada Eisuke 
Published: July 2007

AbstractA novel concept of structure and control of linear induction motors (LIMs) called “Flux Synthesizing Linear Induction Motors (FSLIMs),” is proposed where each slot has a conductor carrying an electric current whose amplitude and phase angle are controlled with super multiphase switching devices. It is well known that an LIM has the merits of direct drive and simple structure. However, a conventional LIM has low power factor and energy efficiency. The end effect is one of the significant reasons for the bad characteristics. Strategies against the effect have been limited by conventional three‐phase winding.On the other hand, high‐speed power‐switching devices are available at a reasonable cost. A super multiphase drive enables more freedom for controls with the proposed structure of the FSLIM. Basic characteristics of a tubular test LIM with twelve slots have been measured and calculated to investigate an appropriate flux synthesis. As a result, an appropriate switching scheme which synthesizes sinusoidal distribution of the gap flux density, enables the end‐effects to be suppressed and, consequently, improves the energy efficiency. In addition, basic conditions for the field‐coordinated oriented control of a thrust force are satisfied by keeping the amplitude of the gap flux constant with the flux synthesis.
Characteristics of linear actuator with semiclosed magnetic circuit excited by discharge current of capacitor
Authors: Maeda Tsutomu , Fujita Hiroshi 
Published: July 2007

AbstractThe simple structured linear actuator considered in this paper is based on the model, called the single‐phase oscillating motor, proposed by Jayawant. Reports have already been made on the static and kinetic characteristics of the actuator of the model proposed by the authors for two cases considered and not considered the magnetic saturation when it was driven by an ac source. Although the theoretical procedure to calculate the characteristics is very simple, the calculated results in both cases have shown close agreement with the experimental ones.To improve the actuator for practical use, some methods will be considered and one of them is to use a dc source instead of an ac source. Using the charged capacitor as a dc supply, an instantaneous large current flows easily in the exciting coil in comparison with the case of an ac supply.In this paper, qualitative explanation of the ring motion and calculated results of the ring speed which have good agreement with experimental results are reported.
Power oscillation damping by superconducting magnetic energy (SMES) storage unit
Authors: Ogimoto Kazuhiko , Masuda Tatsuo , Inabe Hiroto , Komukai Toshihiko , Tsuruta Syunichi , Momotake Toyofumi 
Published: July 2007

AbstractWith the increase in the size and capacity of electric power systems and the growth of widespread interconnections, the problem of power oscillations due to the reduced system damping has become increasingly serious. Since a Superconducting Magnetic Energy Storage (SMES) unit with a self‐commutated converter is capable of controlling both the active (P) and reactive (Q) power simultaneously and quickly, increasing attention has been focused recently on power system stabilization by SMES control.This paper describes the effects of SMES control on the damping of power oscillations. By examining the case of a single generator connected to an infinite bus through both theoretical analyses and experimental tests (performed with a SMES unit with maximum stored energy of 16 kJ and an artificial model system), the difference in the effects between P and Q control of SMES is clarified as follows:

In the case of P control, as the SMES unit is placed closer to the terminal of the generator, the power oscillations will decay more rapidly.
In the case of Q control, it is most effective to install the SMES unit near the midpoint of the system.
By comparing the P control with Q control, the former is more effective than the latter based on the conditions that the SMES unit location and the control gain are the same.
A control method for improving ac input current waveform of current‐type PWM rectifiers
Authors: Sato Yukihiko , Miyazawa Hideki , Kataoka Teruo 
Published: July 2007

AbstractRecently, PWM rectifiers which realize high‐power factor and almost sinusoidal ac input current have been proposed and some of them have already been put into practice.In many cases the PWM rectifiers are of current type, that is, they have a smoothing reactor on the dc side. In such rectifiers, anLCfilter has to be inserted on the ac side to reduce current harmonics due to the PWM operation. However, theLCfilter may cause waveform distortion and transient oscillation of the ac side current.As a solution to this problem, a new control method is proposed introducing ac side current control by means of state feedback of theLCfilter. In this case, both the dc output current and the ac input current controls should be achieved by the PWM operation of the rectifier. Furthermore, to obtain sufficient controllability regardless of the operating condition, the dc output and ac input current controls should be done independently. To meet these requirements, existing control methods for PWM rectifiers are not directly applicable.In this paper, a novel control circuit configuration and a method of generating a PWM pulse pattern suitable for the proposed control method are described in detail. From the viewpoint of stability, feedback coefficients and circuit parameters are investigated on the basis of root locus analysis.Some experimental results also are shown to confirm the effectiveness of the proposed control method and the validity of the analytical results. Improvement of the ac side current waveform and the stability of the transient response are demonstrated by these experimental results.
A study on technical feasibility of applying tubular linear induction motor to vertical movement
Authors: Morizane Toshimitsu , Koseki Takafumi , Masada Eisuke 
Published: July 2007

AbstractIt is necessary for a linear induction motor (LIM) to have large thrust force in applications for the vertical movement. If it does not have sufficient thrust force, it cannot lift even itself. A ratio (thrust force/weight of motor), therefore, is the most important factor for the design of this motor.In this paper, assuming the LIM has no slot‐effect and infinite length, a simple analytical model is introduced for steady‐state operation. By comparison with the results of detailed numerical analysis, it is verified to be applicable for basic evaluation of the motor. The design of the motor for vertical movement is carried out and the ratio is maximized. The basic dimensions of a feasible motor are given for such application.
Simulated power source based on output characteristics of solar cell
Authors: Tanaka Kunio , Sakoguchi Etsuo , Yamada Eiji 
Published: July 2007

AbstractNumerous studies were performed to evaluate the performance of photovoltaic power systems (PV systems), including maximum power control of the solar cell, effects of the PV systems on distribution feeders, long‐term performance of the PV systems, etc. To estimate the performance of PV systems, the output characteristics of the solar cell should be taken into consideration.This paper proposes a new method of the simulated power source (SPS) to analyze the PV system. The SPS is under the control of the 10 cm2 reference solar cell, hence, the output characteristics of the SPS are in proportion not only to the static output characteristics of the reference solar cell, but also the dynamic ones.
Power‐system stabilizing control by SMES using fuzzy techniques and neural networks
Authors: Kawakita Yasuhiro , Ohsawa Yasuharu , Arai Kenji 
Published: July 2007

AbstractIt has been clarified that a superconducting magnetic energy storage (SMES) is very effective for power system stabilization. The control methods proposed for power system stabilization by SMES include the pole assignment, the optimum control, and so on, each of which, however, has its drawbacks. The application of fuzzy control is considered to overcome these drawbacks.This paper considers the power system stabilization by fuzzy control of the active and reactive power of SMES. First, the adequate fuzzy control rules of an SMES for the model power system is derived. Then, to alleviate the dependence of the fuzzy control on the operating condition and the fault, a method is proposed which adjusts the fuzzy parameter according to the operating condition and the fault using a neural network. The validity of the proposed method is examined by computer simulations.
Multifault calculation method for dynamic stability study of electric power systems
Authors: Tanaka Kazuyuki 
Published: July 2007

AbstractFor the fault condition in dynamic stability study, balanced faults have mainly been utilized. Recently, however, with the progress of system protective control technologies such as the multiphase reclosing system for a faulted transmission line, the needs for stability software which would be able to calculate simultaneous faults without any restrictions on fault types, total numbers or location, have been increasing.This report presents the newly developed multifault calculation method based on symmetrical components which is able to calculate simultaneous faults without any restrictions on combination of fault types, and total numbers or location. Fault types consist of balanced/ unbalanced ground fault, short‐circuit fault, line‐out of transmission lines, and short‐circuit of series condenser. The proposed method also allows for calculation of faults at an arbitrary location on the line without any topological changes of each symmetrical network even if the faults include line‐end faults with ensuring outages.An example was shown to clarify the validity of the proposed method. Moreover, transient stability limits under the various fault conditions also were discussed.
Compensation characteristics of shunt active and series active power filters
Authors: Peng F. Z. , Kohata Masakazu , Akagi Hirofumi 
Published: July 2007

AbstractActive power filters have been used in practice to suppress the harmonic interference in power systems. To compensate for harmonic currents of loads, active power filters usually are connected to power systems in parallel with the loads. These filters, which are called shunt active filters here, are very effective for loads that can be considered as current sources, such as thyristor rectifiers with large dc reactances. Many papers have covered the shunt active filters applied to these current‐source loads, however, none has discussed characteristics of the shunt active filters when they are applied to voltage‐source loads.On the other hand, since more and more diode rectifiers with capacitive dc filters have recently been used, harmonics generated by them have become an issue. The diode rectifier with capacitive dc filters behaves as a voltage source rather than a current source. When a shunt active filter is applied to such a diode rectifier, the current injected from the shunt active filter may flow into the diode rectifier. As a result, harmonics of the source current cannot be reduced effectively, and harmonic current flowing into the diode rectifier increases greatly.This paper presents the aforementioned problem of shunt active filters analytically and experimentally. Then a series active filter is proposed to suppress the harmonic current of the diode rectifiers. The features, operating conditions, and considerations of shunt active filters and series active filters are described analytically and demonstrated experimentally. Taking a diode rectifier with capacitive dc filter as a typical voltage‐source load, compensation characteristics of shunt active filters and series active filters are discussed by experiment and simulation. The validity of the series active filters is illustrated experimentally.
An expert system for switch operation planning on line dispatching
Authors: Haba Toshiaki , Maeda Shigeo , Watanabe Dai , Fukui Chihiro , Nomoto Masaaki 
Published: July 2007

AbstractAn expert system is presented that produces the operation sequence for disconnecting apparatus from a power system under normal operating conditions.To maintain the reliability of power supply on the network during the operation, the operation sequence must be produced in due consideration of network states, such as load factors and routes of transmission line. Besides, since the network which the system manages includes many high‐voltage consumers, the operation sequence for each consumer should be divided into detailed switch operation sequence.To produce a detailed switching operation sequence simultaneously with macronetwork operation sequence, we introduce the multilayered object‐oriented network model for the knowledge base of this expert system.Each layer of this model represents network configuration in the different degree of detail, and the consistency between states of layers is maintained by an interlayer message‐passing mechanism. On the layer which represents apparatus and their connections in detail, the inference engine can generate the switching operation sequence. On another layer which represents control centers and consumers, the inference engine can search for routes of power supply and can generate the sequence of changing over the network. Therefore, by using each layer properly, the inference engine can produce various kinds of operation sequences.Furthermore the object‐oriented network model facilitates maintenance and extension of the system.
Overvoltage phenomena caused by disconnecting motor‐loads on power line with open‐phase
Authors: Himeno Takashi , Okamura Yukio , Asada Minoru , Nakamura Toshihiro 
Published: July 2007

AbstractThis paper describes overvoltage caused by disconnecting a lot of motor‐loads on a power distribution line with power‐factor‐correcting capacitors during a transmission line open‐phase. The overvoltage phenomena are studied by a field test, a steady‐state analysis and a transient analysis. Experimental results show that the line‐to‐line voltage on a 6.6 kV distribution line with an open‐phase 22 kV transmission line amounts to 1.7 per unit. The overvoltages are caused by two types of resonance. One is the linear circuit resonance between the power‐factor‐correcting capacitors and the secondary side impedance of motors. The difference between positive components and negative ones of the impedance produces the resonance. The other is the nonlinear circuit resonance between the power‐factor‐correcting capacitors and the saturated reactances of a transformer.
Effect of defects and moisture on insulation characteristics of XLPE insulated cable
Authors: Katsuta Ginzo , Toya Atsushi , Kanaoka Mamoru , Katakai Shoshi , Maruyama Yoshio , Muto Hideji 
Published: July 2007

AbstractSample cables having a few types of defects (such as voids, contaminants, and protrusions) with more volume than usual, were prepared intentionally to clarify how these defects affect separately insulation characteristics under the presence/nonpresence of moisture. In the case of void inclusion, insulation characteristics are even more susceptible to ac voltage than impulse voltage, and the distribution of lifetimes is classified into a wornout failure type due to discharge deterioration.While protrusions and some other contaminants can greatly deteriorate original dielectric strength, these defects have a relatively slight effect on long‐term endurance in the atmosphere. Therefore, the distribution of lifetimes is classified into an early‐failure type. With reference to the influence of moisture, in a strong electric field (exceeding 15 kV/mm) and in a short‐term region, there is an increase in harmfulness around defects with water absorbed, thereby inducing electrical trees and resulting in a breakdown. In the light electric field (no more than 15 kV/mm) and in a long‐term region, harmfulness of defects will not deepen to a considerable extent, and the growth of water trees very possibly is influential.
Pulse switching characteristics of MAGTs for pulsed power applications
Authors: Endo Fumihiko , Atsumi Kaoru , Okamura Katsuya , Watanabe Yukio , Kaneko Eiji , Ohshima Iwao 
Published: July 2007

AbstractFor pulsed power systems such as lasers and accelerators, semiconductor switches with their longer service life have actively been developed as replacements for thyratrons. The MOS‐driven thyristors are suitable for pulsed power applications because they have high‐power handling and fast turn‐on capabilities. The MOS‐assisted gate‐triggered thyristor (MAGT), designed especially for pulsed power, is a promising candidate in this field.This paper presents the results of an investigation into the performance of MAGTs. Using a pulse‐forming network (PEN), the pulse‐switching characteristics and the dynamic resistance characteristics during the current flow are investigated. A maximum current density of 21.8 kA/cm2anddi/dtof 106 kA/μs/cm2with 1550‐V anode voltage on a single‐shot basis were obtained. Furthermore, a life test with 109shots at a high repetition rate showed no degradation in the observed characteristics. Based on these experimental results, a carrier flow model of MAGT during turn‐on process is proposed and the turn‐on mechanism is considered.
Analysis of estimation error of observer for disturbance torque and velocity
Authors: Shimada Akira 
Published: July 2007

AbstractThis paper analyzes some features of estimation error of the observer which estimates disturbance torque and velocity. This observer inputs the information of driving torque and current position, and outputs the information of disturbance torque and velocity.Although this observer is a practical tool to compose a robust control system, there has never been sufficient information to make the most of it. Thus the study to grasp some basic features of the observer is needed now. Also, it is very important to analyze the estimation error on it.This paper considers the estimation error caused by disturbance torque and observation noise because these seem to be the most significant causes. The result of analysis provides a practical way to select the pole allocation of the observer. Finally, the simulation and the experimental results are shown.
Development of cable fault location method using fiber optic distributed temperature sensor
Authors: Takinami Naoki , Chino Takashi , Yoshida Shotaro , Miura Isao , Watanabe Kazuo , Amano Kazuo 
Published: July 2007

AbstractWhen ground‐fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground‐fault test using a thermocouple as a temperature sensor with test cables [4].A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground‐fault test. This article describes the outline of the test.
Real‐time digital simulator for power system analysis
Authors: Sato Nobuyuki , Nakazawa Taro , Yamazaki Akira , Taoka Hisao , Iyoda Isao , Noguchi Hideo 
Published: July 2007

AbstractTo understand a number of power system phenomena and to predict critical conditions in system operation, such as voltage collapse, a real‐time simulator able to model the dynamic behavior of large power systems has been needed for a long time. The need for real‐time simulations stems from the fact that in many practical situations it is desirable to test new equipment and analyze the dynamic behavior of a large power system using the actual pieces of equipment.A new digital simulator was developed based on a hypercube‐type massively parallel computer to achieve this objective. The new simulator features: (1) real‐time simulation of a large power system which covers transient stability through long‐term behavior with constant accuracy level; (2) user‐friendly man‐machine interfaces which mimics an actual operating environment and realtime data presentation on a CRT; and (3) high‐speed digital/analog conversion interfaces which connect the digital simulator to actual equipment.
Protective system for a high‐power capacitor bank
Authors: Sato Yasuhiro , Hirano Yoichi , Yamaguchi Sataro 
Published: July 2007

AbstractA new protection system for capacitor banks in the case of a short‐circuiting accident is described. A pulsed power system composed of many capacitor units and closing switches is well known for producing a controlled pulse current of high power as for the power source of a plasma experimental device, etc. According to the increase of capacity of a bank system, it becomes important to protect the whole bank system from a short‐circuiting accident in a capacitor unit.Although some protective ideas have been proposed, these conventional ideas have not been sufficient to absorb the energy flowing into the failure unit from other normal units. Constructing the new 1‐MJ capacitor bank for a plasma experimental device, a newly conceived protective device is designed. The new protection system can absorb the bank energy and suppress the short‐circuiting current flowing into the failure capacitor units, and overcomes the defect in former protection systems. To confirm the utility of a new protection system, a test of a protection resistor imitating the actual bank circuit was made. The test result showed that absorbable energy for the unit ceramic resistor amounted to 1500 Joule/cc. The new system is adopted to the bank system of the TPE‐1RM15 plasma experimental device.
Intra‐aortic balloon pump driven by a linear pulse motor
Authors: Yamada Hajime , Wakiwaka Hiroyuki , Yano Takeshi , Watarai Akira , Karita Mitsuji , Morimoto Masami 
Published: July 2007

AbstractThe Intra‐Aortic Balloon Pump (IABP) is an effective device in assisting circulation. However, a small‐sized IABP is required in related fields.This paper proposes a new small‐sized IABP which is driven by a Linear Pulse Motor (LPM) rather than an air‐driven motor. In general, the LPM has advantages of high thrust/input power and good controllability. The developed LPM for the IABP drive has high thrust/input power of 19.9 newtons/W. It also has kinetic thrust of 270 newtons at the range of speed from 100 to 140 mm/s. The IABP using the LPM has an extremely simple construction. As the result of mock testing, the IABP using an LPM not only gives the same performance as the ordinary air‐driven IABP, but the mass of the IABP will be reduced to half the size of the ordinary one.