IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 116 , Issue 6
Showing 1-16 articles out of 16 articles from the selected issue
  • Yoshifumi Ohura, Mitsuhiro Furuse
    1996 Volume 116 Issue 6 Pages 635-638
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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  • Yoshinori Minato, Yoshihide Yokoi
    1996 Volume 116 Issue 6 Pages 639-647
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    We presented the forecasting method of economic and social indexes in the preceding paper. In this paper, we describe and evaluate the forecasting method of an region's electric power demand in terms of kWh per capita based on the results of the prefecture statistics. It can be seen that kWh per capita has strong correlation with private expenditure for light use and also with the third sector production amount for business use. Thus, the correlation depends on the type of electric services.
    In the case of forecasting more detailed area kWh per capita such as within a region in the prefecture, the relation between the region's kWh and the average kWh per capita can be estimated from a multi-correlation equation with two variables. Those variables are the industrial structure designated with employee by industrial sector and the population gravity among the division. This method is especially useful for estimating light use and business use.
    At the same time, time-series analysis and exponential smoothing method are used together and discussed here for the case of forecasting more detailed kWh in an area smaller than the region.
    The method of forecasting kWh in each mesh and managerial area for distribution system was developed and evaluated.
    Then, the maximum peak power, light use power and midnight power in August and December are estimated by summing up each load curve calculated from forecasted kWh in the respective month.
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  • Naoyoshi Shimokura, Nobuyuki Kaya, Masaki Shinohara, Hiroshi Matsumoto
    1996 Volume 116 Issue 6 Pages 648-653
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The Kansai Electric Power Company has succeeded in power transmission by means of aerial microwave in cooperation with Kyoto and Kobe Universities. We set a parabola antenna of a diameter of 3m for the transmission antenna, and a square-shaped Rectenna (termed as an abbreviation of Rectifying Antnna) array of 3.2m×3.6m for the receiving antenna. The distance between the transmitter and the receiver was 42m. We finally gained the receiving power of 0.75kW for the transmitted power of 5kW.
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  • Yu Huang, Shinichi Iwamoto
    1996 Volume 116 Issue 6 Pages 654-661
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Conventionally, most of voltage stability indices, including Voltage Stability Proximity Index (VIPI), have been formulated for the overall system. Voltage instability phenomena, however, can occur locally and then cause cascade collapses throughout the system. Therefore, it is of significant importance to establish an index that can locate the possible voltage collapse buses in power systems efficiently. In this paper, we show the local property of the information of multiple solutions in load flow calculation and its use in voltage instability assessment. It should be noted that this kind of information is formatted in the voltage space rather than in the specified value space. Therefore, it adds difficulties to obtain the information of the specified value space, and the qualitative property in a simple one-machine one-load (two-bus) power system may not be true for multi-machine multi-load power systems. We show our investigations by considering several model systems quantitatively comparing with the two-bus power system. Taking the advantage of the power flow formulation, it can be concluded that the localization of the voltage variation vector that indicates the initial direction of the voltage collapse will provide exact information for distinguishing the problem buses in the system. The nose curves of problem buses can be obtained for monitoring purposes at the same time. With the application of these results and VIPI, an emergency countermeasure is suggested for monitoring and delaying possible voltage collapse in the stressed power systems.
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  • Masahiko Nambu, Yasuharu Ohsawa
    1996 Volume 116 Issue 6 Pages 662-670
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Since a power system is a huge system which essentially includes nonlinearities, it is difficult to design a controller for system stabilization as it is. Therefore, the controller design is usually done for the linear system linearized at the stable operating point. When system parameters are changed, however, because of some faults or load shedding, the above designed controllers may not be effective.
    In this paper we propose a new method for the design of power system stabilizer using the differential geometric linearization approach. The nonlinear controller has the information at the secondary bus of the step-up transformer as the input signals, which enables the application of the proposed method to multi-machine power systems. The method was tested on multi-machine power system model, and it was proved that the proposed method is very effective and practical for power system stabilization.
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  • Pyong Sik Pak, Yutaka Suzuki
    1996 Volume 116 Issue 6 Pages 671-677
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The characteristics of a CO2-capturing hybrid-type power generation system utilizing both the fossil fuel and solar thermal energy were investigated. In the system, relatively low temperature saturated steam is produced by using solar thermal energy and is utilized as the working fluid of a methane-firing gas turbine system. The proposed system is a hybrid-type system in which generated CO2 is recovered based on the method of oxygen combustion, and thus a high efficiency system without both emission of CO2 and thermal NOx. can be expected to be possible to construct even in the region where solar radiation conditions are not so good. The system with 1ha collector area was assumed to be constructed in Osaka city, and its characteristics have been investigated. It has been estimated through simulation study that the proposed system has high exergetic efficiency of 63.8% on the basis of the fuel exergy even when generated CO2 is captured, and that the net generated power is 1.75MW, capacity factor is 17.7%, and total exergetic efficiency is 19.6%, being 1.61, 1.70, and 1.61 times high, respectively, compared with that of a conventional solar thermal power generation system. It has also been shown that the system has relatively 32% higher exergetic efficiency compared with a future high-efficiency photovoltaic power generation system.
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  • Tanzo Nitta, Yasuyuki Shirai, Yukikazu Ito
    1996 Volume 116 Issue 6 Pages 678-684
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In this paper, a new application of Superconducting Magnetic Energy Storage (SMES) for diagnosis of power systems is proposed. Basic experiments for diagnosis of power systems by use of SMES were carried out by use of small generators, artificial transmission lines and a small SMES. The SMES gives small power disturbances to the power system without affecting oparating conditions of the power system. The small power oscillations in the power system due to continuous pbwer disturbances generated by SMES are observed. The relations between the power disturbances and the power change of SMES are discussed. Natural frequencies of the power system are obtained by investigating the oscillations due to the sinusoidal power change of SMES. The relations between the natural frequencies and the steady state stability of the power system are discussed, too. The possibility of estimation of the steady state power system stability by monitoring the natural frequencies of the operated power system by use of SMES can be shown experimentally.
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  • Takehisa Hara, Osamu Yamamoto, Minoru Kitagawa, Susumu Ono
    1996 Volume 116 Issue 6 Pages 685-691
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In order to make clear the mechanism of double circuit accidents that occur on power transmission lines, an accurate multi-phase flashover analysis on transmission towers is necessary. This multi-phase flashover analysis is made for an 500kV transmission line when one of towers is struck by lightning. The nonlinear inductance model of the arcing horn gap is added to the authors' previously proposed tower model. The tower model can precisely calculate every arm voltage and the gap model can well simulate the flashover phenomenon from leader extension to breakdown. It is found that the probability that occurs flashover among more than 4 phases is considerably high for the case of lightning current with 200kA amplitude and 100kA/μs wave crest. On the contrary, flashover among more than 2 phases does not take place in either case where the lightning current amplitude is less than 100kA or the wave crest is less than 50kA/μs.
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  • Tetsuhiko MAEDA, Tetsuya SUEKANE, Shigeharu KABASHIMA
    1996 Volume 116 Issue 6 Pages 692-697
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Two-dimensional numerical simulations taking into account the boundary layer were carried out to confirm the mechanism of improvement in enthalpy extraction ratio with enhancing the area ratio of generator and with introducing the inlet swirl. For the generator having the large area ratio, static pressure is kept low throughout the MHD channel against the Lorentz force, and higher gas velocity and Hall parameter results in the improvement of generator performance due to large electromotive force. Introduction of inlet swirl also results in low static pressure and high Hall parameter, and high enthalpy extraction ratio can be achieved. Lorentz force gives rise to characteristic secondary flow field in azimuthal velocity component.
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  • Koichi Hori, Masao Ohtsuka, Masanori Hara
    1996 Volume 116 Issue 6 Pages 698-705
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The thermal deterioration of the contacts in SF6 gas has not been generally understood. This paper describes the sulfide formation by the direct reaction of Ag and Cu to SF6 gas with moisture at a relatively low temperature, and the current carrying deterioration of contacts by such formation. The results are summarized as follows :1) the thermodynamical approach shows that Ag and Cu react to SF6 with moisture over 252°Cand 165°C, respectively, and then Ag2S and Cu2S are produced, 2)these reaction temperatures are supported by the experiments and much sulfide is produced by higher temperature and moisture and 3) the 160-280 A current carrying tests of the Ag-WC and Cu-W contacts with high contact resistance of about 1mΩ show that only the Cu-W contacts over the sulfide forming temperature were covered with a copper sulfide layer and therefore could not carry these currents after 55-130 hours. To examine the rise of contact resistance for the actual Ag-WC and Cu-W contacts by arc erosion, the switching tests of 200 A and 20, 000 operations were also carried out and the Ag-WC and Cu-W contact resistances at 0.01% occurrence probability were recognized to be 0.7 and 1.3 mΩ, respectively. Therefore it is concluded that the Ag-WC is sulfide reaction free but the Cu-W possibly produces copper sulfide under the above conditions.
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  • Tamaki Matsuura, Noda Taku, Naoto Nagaoka, Akihiro Ametani
    1996 Volume 116 Issue 6 Pages 706-711
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper proposes a simple and efficient method for calculating a transmission line transient including its frequency-dependent effect. The frequency-dependent distributed-parameter line is modeled by a combination of a distributed-parameter line with constant loss and velocity and a lumped-parameter circuit representing the frequency dependence of the original line. The lumped parameters are derived from a four-terminal parameter theory. Calculated examples by the proposed method are compared with the accurate results by a frequency-domain transient program FTP, and by the EMTP. The comparison shows the accuracy of the proposed method is satisfactory.
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  • Tetsuya TAYA, Tetsuya SUEKANE, Yoshihiro OKUNO, Shigeharu KABASHIMA
    1996 Volume 116 Issue 6 Pages 712-717
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The feasibility of radio-frequency (_??_ MHz) pre-ionization is examined in a non-equilibrium disk MHD generator channel under no externally applied magnetic field with γ-z two-dimensional numerical simulation. Non-equilibrium seeded plasma with electrical conductivity sufficient for high power generation can be realized in the supersonic nozzle where the electric field is induced almost uniformly by the induction coils. The radio-frequency electric power required for the pre-ionization becomes less with the decrease in the seed fraction. The ratio of the required electric power to the thermal input of generator channel is of the order of 10-3_??_10-2. The effects of induction coil current and frequency on the plasma properties are also discussed.
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  • Hiromichi Kobayashi, Yoshihiro Okuno, Shigeharu Kabashima
    1996 Volume 116 Issue 6 Pages 718-723
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The influence of inlet pressure fluctuation on performance of disk CCMHD generator is examined with γ-θ two dimensional numerical simulations. It is confirmed from the simulation concerned with the behavior of the impulsive pressure disturbance that Magneto-acoustic waves exist even under the condition of fully seed ionization in γ-θ two-dimensional plane. Small continuous inlet pressure fluctuations about 1% are found to reduce the output power hardly. The large fluctuation about 10% can cause the ionization instability and result in the slight reduction of the performance.
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  • Hidehiko Okada, Yositeru Tutinaga, Ryozo Itoh, Fujio Irie
    1996 Volume 116 Issue 6 Pages 724-730
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    To scale up the capacity of a SMES for a practical application, it should be necessary to adopt a high voltage system, a large current system or a module type system. The first system is difficult because of the very low withstanding voltage of a superconducting coil and second one also leads difficulties such as multiple connections of many units of convertors at dc side and large current conductors of superconducting coil. The third system which is composed of some numbers of modules with small scale convertor units and element coils might be a solution of above difficulties. In this module type system, module coils have magnetic linkage one another.
    In this paper, the influence of magnetic linkage between coils of a module type SMES are investigated by computer simulation. The magnetic linkage is different with numbers of modules and connection method of coils. By the effect of this magnetic linkage, each module coil current is different at same power of each module convertor. The transfer characteristcs of current and energy are shown for discharge from one or some modules of 6 modules consisted of 18 coils. Discussions are made on the situation of existing an unused module at the quench. And the transfer with same current of each module is shown by control of convertor power of the current feedback.
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  • Isao Oki, Takeshi Haida, Yoshio Izui, Seiji Kobayashi
    1996 Volume 116 Issue 6 Pages 731-740
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The power equipment such as GIS (Gas Insulated Switchgear) plays an important role for stableness and reliance of electric power supply. Although the advantages of GIS are maintenance free and long-term stability, there exists the necessity to develop predictive maintenance system to avoid fatal mal-functions in case. The objective of predictive maintenance is detecting small symptoms of partial discharge within GIS in service. The NN (Neural Network) characteristics of learning and self-organization are expected to show better performance for realization of predictive maintenance system. This paper presents the NN architecture of ICLNN (Incremental Cluster Learning Neural Network), the architecture of diagnostic system, and experimental results using simulated abnormalities. The purpose of development of ICLNN is real time learning of normal status at the actual site. This is required because NN should be trained for the background noise to define normal status. The normal status is easy to define and lots of data for this status are available, though complete sets of abnormal status are difficult to define and need many experiments to obtain training data. The experiments are conducted using simulated abnormalities of various lengths of metal particles. The results exhibit the advantages of ICLNN diagnostic system over conventional amplitude threshold system for some cases. They also show the limitation of the performance of both systems.
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  • Hirotaka Yamamoto, Toshihiko Ganke, Hirofumi Miki, Kenji Sugimoto
    1996 Volume 116 Issue 6 Pages 741-747
    Published: May 20, 1996
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Fuel cell using liquefied petroleum gas (LPG) as fuel have never been operated for a long period of time in Japan. Our company started verification research of phosphoric acid fuel cell (PAFC) using LPG as the fuel at the end of May, 1992 for a scheduled period of about three years. This paper is described two PAFC technics. One is the effective maintenances of the PAFC system in addition to suitable condition for reforming. LPG-reformer is operated by conventional nickel-groupe catalyst and new noble-group catalyst; the former invited pressure loss growing by carbon deposition, the latter keep stable reforming. And, as the value of steam carbon ratio (S/C) reduces, the waste heat increases. The demonstration PAFC was operated over 3, 000 hours on condition that S/C=3.0 (with the rated S/C=3.5) for LPG. The other is estimation of performance history of fuel cells by analyzing polarization curves; ohmic, activity, and concentration polarization components.
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