IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 114 , Issue 5
Showing 1-16 articles out of 16 articles from the selected issue
  • Yoshitaka Nitta
    1994 Volume 114 Issue 5 Pages 433-436
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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  • Shingo Shirakawa
    1994 Volume 114 Issue 5 Pages 437-442
    Published: May 20, 1994
    Released: December 19, 2008
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  • Suresh Chand Verma, Koichi Nakamura, Katsuhiko Naito, Mototaka Sone, H ...
    1994 Volume 114 Issue 5 Pages 443-451
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper presents a new variant of sparse approach for fast power flow computations. The proposed approach features a new and fast node ordering scheme, the realization of an index search operation (usually involved in LU decomposition) only once by shifting it out of the iterative loop of Newton-Raphson (NR) based power flow computation, the adoption of static and simple data structure, and the implementation detail designed to extract the advantage of pipe line feature. The proposed approach is tested using a single chip pipe lined processor, called as Digital Signal Processor (DSP) and is found to suit well to this type of processors. The DSP is made operative by using personal computer (PC) as its host and the whole system is named as DSP system. For the several test systems considered, the complete job of performing power flow computation is assigned to DSP only. The significant reduction in the computational efforts with the proposed sparse variant over conventional approach is obtained while the computing time is observed to vary linearly with the change in system size.
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  • Tomoatsu Ino, Chikasa Uenosono
    1994 Volume 114 Issue 5 Pages 452-459
    Published: May 20, 1994
    Released: December 19, 2008
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    It is pointed out that frequency dependent effects of some elements of transformation matrix of double circuits transmission line constructed by current eigen-vector formings contradict physical causal relationship. This contradiction may be a substantial factor of error for any expression of a transient program in modal frame.
    This paper presents a technique to remove the contradiction and to stabilize the characteristics in low frequency by means of modification of line constant. The technique is effective for double circuits DC transmission lines with neutral lines and make the apporoximation process by low order transfer function simple.
    Effect of the modification is included in equivalent circuits composed of integrated resistance accounted at low frequency and modified distributive line. The transient behaviour of the equivalent circuits are closely similar to these of Fourier tranformation.
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  • Susumu Kyuwa, Tadayoshi Yosida, Kazuya Omata, Shinji Yuasa, Kenichi Mi ...
    1994 Volume 114 Issue 5 Pages 460-468
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Various stabilizing equipments have been installed in modern power systems to enhance power system stability and its stabilizing algorithms have become more complicated(3).
    Most of training simulators, however, simulate a power system by performing power flows and frequency deviation calculations(2). Since these simulators ignore dynamics of individual generators, it is impossible to simulate power swings and out-of-step phenomena which are closely connected with these equipment's actions. To simulate these actions automaticaly in the training simulator, a transient stability calculation program must be incorporated.
    There are two methods. In one method, a transient stability calculation program is linked to a conventional training simulator using an event sequence file and called every time it is required(4)(5). In the other method, a training simulator involvs a transient stability calculation program itself and simulates the generator dynamics and stabilizing equipment continuously(6). However, to adopt the latter method, a transient stability calculation program that can simulate power swings in real time must be developed. The application of this method to a large power system with more than 100 generators has not been reported so far.
    This paper presents a transient stability calculation method which can simulate a large power system with more than 100 generators faster than real phenomena, and it's application to a training simulator.
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  • Tomonobu Senjyu, Naoki Gibo, Katsumi Uezato
    1994 Volume 114 Issue 5 Pages 469-474
    Published: May 20, 1994
    Released: December 19, 2008
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    This paper proposes the cooperative control of AVR and GOV taking the uncertainty of a state variable into consideration to improve transient stability of power systems. The control laws based on sliding mode control are very simple, and are introduced to take the uncertainty of the state variable into consideration without the linear-approximation of power systems. So, the proposed control has the robustness regarding parameter error and load variation. The state variables which need to control the power system are speed deviation and input/output power of generator only. Therefore, the proposed control can realize in real system easily. The validity and usefulness of the proposed control are tested on a single-machine infinite bus system. It is shown that the transient stability of power system is improved by cooperative of AVR and GOV control sufficiently.
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  • Hideki Fujita, Hisayuki Kurebayashi, Haruo Nohara, Masuo Goto, Yukio K ...
    1994 Volume 114 Issue 5 Pages 475-482
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Recently, power systems are becoming larger and more complex. Particularly, the looping of power systems are becoming highly desirable in order to improve the stability. The main features of such looped power system are; (i) comparatively less losses, and (ii) improved angle stability as well as voltage stability. But, these systems have demerits; such as, in case of route off fault in a loop power system, power disturbances increase more and more, etc. If these demerits are overcome, the loop power systems are going to be more beneficial. In an attempt to suggest a solution to such problems, this paper describes several results of applying a High Speed Phase Shifter in the control system of a loop power system.
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  • Hiroshi Sasaki, Seiji Sadakuni, Junji Kubokawa, Naoto Yorino
    1994 Volume 114 Issue 5 Pages 483-490
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In recent years, a drastic increase in the number of air conditioners has caused a sharp and narrow peak load in summer seasons due to their inherent temperature sensitive operational characteristics. Power system operational costs can greatly be reduced through an improvement in the load factor, relaxing an impending need of installing new generating plants.
    The main purpose of this study is to reduce the peak power demand by a co-ordinated regulation of a large number of air conditioners that otherwise operate independently. The authors have been studying the effect of the regulation on peak clip by computer simulations. Although a simple reguration scheme is effective to suppress a high peak demand in the time horizon of 2 or 3 hours, a daily peak cannot be reduced only by this scheme. The introductions of priority in the control of each air conditioner group and a small step increase and decrease in temperature settings has been effective to suppress a daily peak load as planned without a large payback. Computer simulations have been carried out on a total of 65 air conditioners that are operating under different environments. Simulations have clearly demonstrated the effectiveness of the proposed method on both daily peak clip and suppression of temporal high peak.
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  • Hiroshi Sasaki, Masayuki Ushio, Yoshifumi Zoka, Junji Kubokawa, Minoru ...
    1994 Volume 114 Issue 5 Pages 491-497
    Published: May 20, 1994
    Released: December 19, 2008
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    A fuel cell has long been expected to be a very energy efficient and clean generation device and matured technologically to a stage of practical use. In consideration of its relatively small generating capacity, a fuel cell may be installed in a distribution network. In this paper, an optimal placement problem of fuel cells on a radial distribution network has been formulated as a mixed integer programming method and an efficient solution algorithm is proposed. The objective function to be minimized consists of electricity cost supplied by a substation, thermal cost by electricity, fixed and operating costs of fuel cells. In order to reduce search space, several constraints have been imposed such as possible locations and number of cells, voltage drops, and DSR (demand side reliability). The proposed algorithm has been tested on a 69 node radial system to obtain a solution within reasonable computation time.
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  • Xifan Wang, Takuro Mochizuki, Zheng Xu
    1994 Volume 114 Issue 5 Pages 498-504
    Published: May 20, 1994
    Released: December 19, 2008
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    Evaluating the benefits of interconnected systems is very important for both planning and operating power systems. Such benefits include lower production costs and a higher level of system reliability. Many papers have been written on the subject using the Probabilistic Modeling method. These papers can be roughly divided into two categories. The first category is based on the cumulant method which is prone to the inherent inaccuracies of series expansions. The second category is so-called the segmentation method which requires a great amount computation when being used in interconnected systems.
    This paper presents a new method of probabilistic modeling for interconnected systems. The method is based on the Equivalent Energy Function approach. To extend the EEF approach to interconnected systems its formulas are slightly altered in form. The proposed method rigorously treats probabilistic properties of residual unit capacities and tie line capacities, and thus accurately simulates the energy exchange processes between two interconnected systems. The numerical examples given in the paper illustrate the high accuracy and effectiveness of the proposed algorithm.
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  • Tadashi Ishizaka, Kenji Yamaji, Yoichi Kaya
    1994 Volume 114 Issue 5 Pages 505-513
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Cogeneration system (CGS), especially new type of CGS which utilizes new generation systems such as fuel cells, is expected to be one of the most efficient energy supply system in urban areas. The supply of a CGS for commercial users, however, is currently limited to one building. The economic advantage and energy efficiency of a CGS could be significantly enhanced by increasing the supply area.
    This paper developed two kinds of fuel cell-CGS simulation models and evaluated the optimal supply areas and layouts for CGS's as well as their optimal scale and operation. It is found that: 1) the optimal size of a CGS depend on various factors such as type of consumer, demand distribution, and particularly initial piping cost; 2) the range of the CGS cost with which CGS can compete with commercial electric power systems is broad enough to allow fuel cell-CGS to be introduced in the market; and 3) the model enables evaluation of the existing demand areas and the applicability of the model is shown using some numerical examples.
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  • Kimiharu Kanemaru, Ryoji Matsubara, Jun'ichi Kaito, Shigehiro Toyota
    1994 Volume 114 Issue 5 Pages 514-522
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Composite Fiber-optic Overhead Ground Wires (OPGWs) have been installed to major power transmission lines. Using these OPGWs, maintenance information systems for power transmission lines have been developed and put into practice. In these systems, however, both sensors and fiber-optic data transmitters are restricted to install on the towers where the OPGW-splicings are made, thus resulting in the restraint of system functions. The authors proposed the application of low-power radio channels and studied the methods both for sensor-signal and OPGW-interpolating data transmission. Specifically, for sensor-signal transmission, it is shown that the method combined with distributed transmission timing and slotted CSMA has superior data transmission performance against hidden terminal problem. Also for OPGW-interpolating data transmission, it is shown that the method using 3 channels of low-power radio has superior performance in view of effective use of radio wave resources. With these results, both sensor-signal and OPGW-interpolating data transmission systems are manufactured and confirmed their practical effectiveness by the field tests.
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  • Pyong Sik Pak, Yutaka Suzuki
    1994 Volume 114 Issue 5 Pages 523-530
    Published: May 20, 1994
    Released: December 19, 2008
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    A multi-cascade heat utilizing power generation system is proposed in which carbon dioxide (CO2) generated is partially recovered by adopting the oxygen (O2) combustion method. In the system, a gas turbine is driven by high-temperature working fluid (air) generated by burning fuel. The turbine outlet gas, which has still considerable energy, is used to generate high-pressure super-heated steam and middle-pressure one at a waste heat boiler (WHB). The high-pressure steam is used for driving an expansion turbine, until its pressure becomes the same as the one of the middle-pressure super-heated steam produced at the WHB. Both the middle-pressure steams are utilized as the working fluid of the CO2-recovering non-polluting high-efficiency gas turbine power generation system, in which the heat energy is also utilized cascade-wisely. It was shown that the system had the net power generation efficiency of 48.4% at the lower calorific value base with CO2 recovery rate of 30.1%, and that this efficiency was remarkably high compared with that of a convensional combined-cycle power generation sys-tem in which a CO2 recovery process is incorporated so as to attain the same CO2 recovery rate.
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  • Jitsuji Ohtsuki, Tatsuyoshi Seki, Masayuki Miyazaki, Akira Sasaki
    1994 Volume 114 Issue 5 Pages 531-538
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Molten Carbonate Fuel Cell (MCFC) has high potential in being used as an energy converter of various fuels to electricity and heat. MCFC yields few envioronmental polutions and meets a reduction in the green house problem. Development of indirect internal reforming molten carbonate fuel cell (IIR-MCFC) was initiated by the Kansai Electric Power Company and Mitsubishi Electric Corporation. IIR-MCFC has several advantages. (1) Higher efficiency is expected because of efficient utilization of heat from cell reaction to reforming reaction. (2) Longer life compared with direct internal reforming MCFC is expected by means of loading reforming catalyst in the cell separated from the electrolyte vapor which causes deactivation of the reforming catalyst.
    A 3kW, a 10kW, a 30kW and a 100kW class stack were operated successfully. Output power of 100kW class stack generated 109kW in IIR mode. (direct methane feed) In the test of the 30kW and the 100kW class stack, PSA (pressure swing adsorption) to separate carbon dioxide from the anode exhaust gas is installed in the anode gas recycle loop to the cathode.
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  • Kazuya Higashibata, Teruo Miyamoto, Kenji Hayashi, Takaho Tanaka
    1994 Volume 114 Issue 5 Pages 539-544
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Life characteristic of the paper based phenolresin laminates was investigated using test samples thermally deteriorated in oil. In addition to a conventional study of static tensile sterength, effects of repetitive stress were also examined.
    The test results revealed a change in deterioration mechanism of the paper based phenolresin laminates at about 170°C while its life time by thermal only deterioration remained very long. The tests on repetitive tensile stress yielded the following characteristic: the slope of S-N curve has a trend to become more flat as the heat deterioration of the samples aggravates and the breaking strength after a duration of tensile stresses tends to converge at about 20% of the strength of new materials.
    Moreover, a good correlation between tensile strength and hardness was obtained. With the use of the life expectation curve obtained from the tests on both static and repetitive tensile strength, it becomes possible to estimate life time in actual operating conditions.
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  • Takeo Wakai, Yasuhiro Matsumoto, Osamu Sakuma, Kazuo Shinjo, Hideki Mo ...
    1994 Volume 114 Issue 5 Pages 545-546
    Published: May 20, 1994
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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