IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 122 , Issue 12
Showing 1-27 articles out of 27 articles from the selected issue
  • Toshiyuki Hayashi
    2002 Volume 122 Issue 12 Pages 1245
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
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  • Junya Matsuki, Norio Takahashi
    2002 Volume 122 Issue 12 Pages 1246-1251
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The 13th Power & Energy Society Annual Conference was held on Aug. 7-9, 2002, in Fukui University. There were 47 sessions, and 480 papers were presented. An invited lecture, panel discussion, discussions on special topics, academic lectures of Hokuriku branch, panel exhibition and technical tours were also organized. In this article, the outline of the conference is reported. society annual conference, submission of paper, administration of conference
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  • Katsuki Kabemura, Kazuhiko Yonekura, Takanori Tsukamoto, Keiichirou Ha ...
    2002 Volume 122 Issue 12 Pages 1252-1261
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper describes the application results of the dispersed autonomous voltage control system, which the authors have proposed, on a real distribution network. This system is effective for regulating the supply voltage of an entire HV line within an optimum range. In the system configuration, a self-control voltage compensator (SCC) is installed together with a static capacitor (SC) or shunt reactor (ShR) on the line. Individual SCCs autonomously control the operation of SCs and ShRs, based on the voltage measured where the SCs or ShRs are located on the line. A field test on a real network proved that the proposed system can sustain a high fault tolerance ability and high cost performance.
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  • Tsutomu Michigami, Kazunori Nara, Hitoshi Omata
    2002 Volume 122 Issue 12 Pages 1262-1269
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The modern electric power system of our country is high density, large-scale and complication. The multimode oscillations occurs in the generator connected with this system. It is being mixed to high-and low-frequency oscillations between the power systems and many other oscillations, such as the SSR and cross-compound machine oscillations, which is specific mode oscillations of generator. In this paper, first the generator actual model that realizes the multimode oscillations is constructed. Next, model reduction of this actual model is done, and design model to use for the control design is composed. Then, the He control design in modem control theory is presented by using this design model which derives damping of power system oscillations and robust stabilization of other multimodes. Finally, a goal for control design is verified by simulation on the actual model with H∞ controller.
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  • Komsan Hongesombut, Yasunori Mitani, Kiichiro Tsuji
    2002 Volume 122 Issue 12 Pages 1270-1279
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper presents an incorporated use of an intelligent method using a micro-genetic algorithm (micro-GA), hierarchical genetic algorithm (HGA), and an analytical method so called a minimum phase control for an off-line power system stabilizer (PSS) tuning in multimachine power systems. First, the problem of selecting proper PSS parameters is converted to a simple optimization problem. Then, the problem will be solved by a micro-GA with a small population and reinitialization process. HGA is also adopted in the encoding process of a micro-GA for the purpose of self-identifying the appropriate choice of PSS locations. Experiences have shown that the time consumed by GA can be hastened if a few legal solutions are used in the GA initialized process. In this paper, a reasonable choice of initial solutions is obtained by a minimum phase control method. These added features provide a considerably improvement of time efficiency and flexibility in PSS tuning of large-scale power sys-tems. A 68-bus and 16-generator system which is complex enough and close to realistic power systems has been used as an ex-ample to validate the effectiveness of the proposed tuning approach. Keywords: power system stabilizer, minimum phase control, genetic algorithm, micro-genetic algorithm, hierarchical genetic algorithm, simultaneous tuning
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  • Tomonobu Senjyu, Yoshiteru Morishima, Takahiro Yamashita, Katsumi Ueza ...
    2002 Volume 122 Issue 12 Pages 1280-1288
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In this paper, to achieve both the damping of power system oscillation and terminal voltage control simultaneously on multi-machine power system, we propose a decentralized H excitation controller. In the proposed method, H control via Normalized Coprime Factorization approach are used to achieve the proposed design idea. By the Normalized Coprime Factorization approach, the weighting function in H control design is simplified, and an output feedback controllers that take into account the realities and constraints of the power systems are designed. The proposed controller is carried out model reduction of H controllers, and is transformed to discrete system to perform digital control by computer systems in consideration of applying for real system. We verify that the proposed excitation controller can achieve both the damping of power system oscillation and terminal voltage control by computer simulations on a multi-machine power system.
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  • Fumio Yamamoto, Hiromu Matsuda, Akio Kitamura, Kiyoshi Takigawa
    2002 Volume 122 Issue 12 Pages 1289-1299
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper describes the test results about ground fault phenomena caused by dielectric breakdown between primary and secondary winding of transformer, which ground fault current flows through B-type earthing resistance. The test results are as follows. The distribution line system keeps three-phase AC voltage waveforms after islanding condition, when the system connects with the single-phase photovoltaic power generation systems and the no-load running three-phase motor-generator load. In this case, the value of the ground faults current decreases after islanding condition. On the other hand, the distribution line system does not keep three-phase AC voltage waveforms after islanding condition, when the systems does not connect with the no-load running three-phase motor-generator load. Depending on the circumstances, the value of the system line to line voltage enlarges 1.7 times, and the value of the ground faults current does not decrease after islanding. These phenomena affect electrical appliances. It is necessary to keep three-phase AC voltage waveforms after islanding condition by certain measures.
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  • Naotaka Okada, Kazuyuki Tanaka
    2002 Volume 122 Issue 12 Pages 1300-1310
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    It has been noted that the voltage of connection points rises according to the reverse power flow when grid-connected photovoltaic systems are concentrated in distribution systems in residential areas. When this happens, the photovoltaic system may control the power generation output to maintain a suitable voltage for the connection point. Designing a demand area power system aiming at free access to a distributed power supply for energy-effective practical use requires a precise understanding of this problem. When analyzing a photovoltaic system mainly connected to a low-voltage system, we looked for a method of analysis in which the high-voltage system and the low-voltage system of a single-phase three-wire system are unified. This report shows use of the indication method between nodes using power flow calculation, for the purpose of developing a technique of analyzing a unified high-voltage system and low-voltage system of a single-phase three-wire system.
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  • Tomochika Maekawa, Noriyuki Hashimoto, Mitsuru Yamaura, Yasuhiro Kuros ...
    2002 Volume 122 Issue 12 Pages 1311-1320
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper describes an error analysis and performance assessment for one-terminal and two-terminal fault locations utilizing impedance measurement techniques for series compensated parallel lines. The one-terminal fault location method is considerably influenced by the series capacitors in series compensated parallel lines. Two major factors which influence one-terminal fault location have come to light. One is the voltage and current components of lower harmonics which are close to the fundamental frequency and are generated when faults occur in series compensated parallel lines. The other is the phase angle difference of the fault current between the fault point and the fault locating point. These factors increase the locating error considerably. The transient solution of the linear circuit equation of the series compensated parallel lines is obtained and it shows that the result coincides with the simulation based on the EMTP model for series compensated parallel lines. Furthermore, two-terminal fault location using the data from both terminals is assessed. A location method using positive-sequence components is simulated with an EMTP model for the lines and shows good location accuracy.
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  • Masashi Ueno, Nobuyuki Fujiwara, Naoaki Fukazu, Tatsunori Sato, Hidehi ...
    2002 Volume 122 Issue 12 Pages 1321-1329
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Conventional voltage control on a distribution line has been carried out by Load Ratio Transformer (LRT) and Step Voltage Regulator (SVR). However, since the object of these control methods is slow voltage fluctuation, the high-speed voltage control system is required according to the spread of electronic equipment. This paper presents a developed 75kVA series Static Voltage Compensator (SVC). This system configuration is the same as the Unified Power Flow Controller (UPFC) which is consists of shunt and series controllers combined with a DC bus. Firstly, a design concept for installing a single pole on the distribution line is described. Furthermore, the field test was carried out on the line that has momentary voltage sag by starting an induction motor. The way of the installed place selection and the parameters setting for calculating the compensated voltage is described. It was confirmed that the voltage control performance of the SVC achieved our desired end, and 75kVA SVC shows the effectiveness of the voltage compensation.
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  • Toshiji Kato, Genyo Ueta, Satoshi Ishii
    2002 Volume 122 Issue 12 Pages 1330-1336
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Impulse test is applied to a power transformer for an acceptance test. When there is a difference between neutral currents for full and reduced impulses, there is a fault winding in the transformer. However it takes a lot of works to find the fault location, many works have been researched to automate the process by using a computer. This automatic diagnosis is a sort of pattern recognition technique and the point is how to find relation between fault locations and measured current waveforms. This paper proposes to use the Kohonen's self-organizing map (SOM) for this automatic diagnosis of fault locations in power transformer tests. In this process, the transfer function method, which computes a transfer characteristic from the applied voltage to the neutral current by dividing the two frequency spectra with the fast Fourier transform algorithm, is useful to avoid dependence on the applied voltage waveform. The following three techniques are proposed in the SOM computation. Winding section division into several blocks is useful to simplify SOM's. Input current waveforms are necessary for symmetrical winding positions to identify faults. Multiple SOM's are effective to improve the diagnosis reliability.
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  • Mitsunori Yamashita, Norikazu Kanao, Hikoni Yanagida
    2002 Volume 122 Issue 12 Pages 1337-1347
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper presents a method for calculating and estimating the parameters of a bus load model in power system stability studies. There are two basic approaches to obtain load voltage characteristics. One is to directly measure the voltage sensitivity of load active power and reactive power at substations or feeders. The other is to build up a composite load model from knowledge of the mix of load class. It is effective to calculate load voltage characteristics by utilizing the feature of both approaches.
    The bus load model we propose consists of a load branch with equivalent impedance to the feeders and transformers in the 66kV or 77kV distribution system, reactive power compensation and load, which is composed of three load classes, such as industrial, commercial and residential. The load voltage characteristics are calculated from voltage and current measured at several feeders, where voltage sag due to a fault occurs. The static load voltage characteristics are represented the exponents, and have correlation with temperature. Exponents of load class are calculated from the measured exponents, temperature and load class mix by least-squares method. The validity to be applicable for the estimated exponents by the exponents of load class and the mix of load classes is evaluated. The bus load using this exponents will be adaptable to not-measured bus loads. They will make stability simulation results more accurate.
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  • Naoto Yorino, Huaqiang Li, Shigemi Harada, Atsushi Ohta, Hiroshi Sasak ...
    2002 Volume 122 Issue 12 Pages 1348-1354
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    This paper proposes a fast computation method to assess the voltage stability of a power system for generator outage contingencies.The load power margins with respect to saddle node bifurcations under faulted conditions are efficiently estimated. Nonlinearities of the power flow equations are partially taken into account to considerablely improve the accuracy of stability assessment. Numerical exami-nations through IEEE 14, 30, 57 bus systems show that, even in such small systems where the effects of generator outage is much larger than those of large systems, maximum error is less than 8%.
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  • Hiroyuki Mori, Hikaru Aoyama, Toshiyuki Yamanaka, Shoichi Urano
    2002 Volume 122 Issue 12 Pages 1355-1365
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In this paper, a hybrid method of data precondition techniques and an artificial neural network (ANN) is proposed to deal with fault detection in power systems. The proposed method makes use of FFT and DA clustering as a precondition technique. FFT is used to extract features of fault currents so that faults to be studied are characterized by frequency domain. DA clustering classifies input data into clusters in a sense of global clustering. DA contributes to the universal clustering that is not affected by the initial conditions. For each cluster, an ANN model is constructed to estimate the location and the type of fault. As ANN, this paper focuses on RBFN (Radial Basis Function Network) due to the better nonlinear approximation. DA clustering is also proposed to determine the centers of RBFN appropriately. Thus, the RBFN model results in one with global structure. The proposed method is success-fully applied to a sample system. A comparison is made between the proposed and the conventional methods.
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  • Yasuhiro Hayashi, Junya Matsuki, Takayuki Ikeda
    2002 Volume 122 Issue 12 Pages 1366-1375
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Open access to electric power transmission networks has been carried out in order to foster generation competition and customer choice in the worldwide. Available transfer capability(ATC) is the largest additional amount of power above some base flow which can be transferred between two sets of buses under constraints such as voltage limit, overloads, stability and n-1 contingencies. Calculation of ATC is important to promote open access to electric power transmission networks. If there are several ATC between two sets of buses, simultaneous transfer capability(STC) of power transmission networks must be calculated. STC is defined as the ability of a transmission network to allow for the reliable movement of electric power from areas of supply to areas of demand. In this paper, a new algorithm to precisely calculate STC is proposed. The proposed method is based on linear programming(LP) based DC power flow and optimal power flow (OPF). Namely, LP base DC power flow is used to obtain the initial solution of STC, and then OPF using successive quadratic programming (SQP) is applied to obtain feasible solution of STC under the operational constraints such as balance of power supply and demand, voltage limit, overloads, generation limit, steady state stability and n-1 contingencies. Furthermore, if power wheeling transactions by several PPSs are simultaneously requested for the transmission network, it seems that the acceptable quantity for the requested wheeling power must be indicated to PPSs from a view point of the transmission network reliability. An algorithm to calculate the acceptable quantity for the requested wheeling power is also proposed by using STC computation. In order to check the validity of the proposed methods, numerical results are shown for 6 and IEEE 30 buses system models.
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  • Yasuhiro Hayashi, Junya Matsuki, Hirotaka Takano
    2002 Volume 122 Issue 12 Pages 1376-1383
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Dispersed generators (DGs) such as fuel cells and solar cells etc. are going to be installed in demand side of power systems. The dispersed facilities can reduce distribution system loss by the appropriate allocation. However, when a DG which has large capacity is disconnected from the distribution network by a fault, violation of the operational constraints such as the line capacity and voltage drop may occur. From a view point of system reliability, robust system configuration for suddenly disconnecting DG from the distribution network must be determined, since system operators can not control DG connection to the network in the on-line. In this paper, the authors propose an algorithm to determine the loss-minimum configuration for a distribution system with DGs maintaining system reliability. Namely, in the proposed algorithm, when the loss-minimum configuration is determined under the line current capacity and voltage drop constraints, n-1 contingencies for DGs are also considered. In order to determine the loss-minimum configuration, tabu search added strategic oscillation is employed. Numerical simulations are carried out for a real scale system model with 118 sectionalizing switches (configuration candidates is 2118) in order to examine the validity of the proposed algorithm. Furthermore, performance of the proposed method is compared with a conventional metaheuristic method, which is Simulated Annealing (SA), through numerical simulations for the system model.
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  • Yusuke Hayashi, Toshifumi Ise, Kiichiro Tsuji
    2002 Volume 122 Issue 12 Pages 1384-1394
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    FRIENDS (Flexible, Reliable and Intelligent Electrical eNergy Delivery System) is proposed as a new con-cept for a future power distribution system. One of the most important characteristics of FRIENDS is that QCC (Quality Control Center) as a power quality control facility is installed very closely to customers in order to supply several qualities of power and enables customers to choose the quality of power. The concept to supply multi-quality of power is called as unbundled power quality service.
    Equipment of Quality Control Center will be different depending on the definition of the power quality. This paper shows the way of definition of power quality and the relation of QCC with the definition. As configurations of QCCs based on AC system, authors propose a new system. The details, simulation and experimental results are shown in this paper.
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  • Tsuyoshi Funaki, Masashi Tanihata, Shunsuke Tanaka
    2002 Volume 122 Issue 12 Pages 1395-1402
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    A voltage source type converter must be linked to a power line through some amount of inductance to restrict the short circuit current. A leakage inductance of a transformer is usually used as that current limiting inductance. The conventional converter control is designed with assuming that the transformer has three-phase balanced equal reactance. This paper proposes novel control system of voltage source type converter, which can manage converter output even if the converter transformer has three phase unbalanced leakage inductance. The proposing control can apply 3 legs type three-phase transformer having three-phase unbalanced leakage inductance to a voltage source type converter, which is cheaper and smaller than three single-phase transformers or precisely well turned 5 legs type three phase transformer having three phase balanced inductance. The proposing control is based on the phase sequence description of the converter system, and the formulization of the system in phase sequence domain is performed in the paper. The control utilizes real time DFT as pre-processing of the control to obtain the state variables in phase sequence domain. The controller indicates the converter to output positive and negative phase sequence voltage in accordance with the transformer impedance, output current reference and AC bus voltage. The theoretical qualitative discussion of the proposing control concept and quantitative evaluation of the proposing control with using computer simulation are presented in the paper.
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  • Tomonobu Senjyu, Takuya Hamano, Naomitsu Urasaki, Katsumi Uezato, Tosh ...
    2002 Volume 122 Issue 12 Pages 1403-1409
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Recently, Permanent magnet synchronous generator (PMSG) is used for wind power generating system. PMSG has the optimal d-axis current which generates maximum power. However, the conventional methods cannot achieve maximum power point operation since d-axis current is generally kept at zero. In this paper, a maximum power point tracking control for wind power generating system with PMSG is proposed. The proposed method optimizes the d-axis current as well as the rotor speed of the PMSG on-line so as to generate maximum power. The effectiveness of the proposed method is verified through digital simulations.
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  • Kimihiro Iwasaki, Atsushi Tanaka, Masahiko Nakade
    2002 Volume 122 Issue 12 Pages 1410-1416
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Our company uses a part of 22kV, and 66kV and 154kV XLPE cables with a waterproof layer in the purpose of preventing water penetration to the insulation. We modeled the water volume of a XLPE cable insulation with waterproof layer as RC series circuit, and we calculated a certain 66kV XLPE cable by using this model. The result was that the time was 35.0 years when relative humidity reaches 50%, and P (Permeation coefficient) equaled 4.4×10-10 [g•cm/(cm2•day•mmHg)].
    Precision of permeation coefficient of present water penetration test is about 10-8 [g•cm/(cm2•day•mmHg)]. At first, we improved the test by reducing the initial water volume and so on. The result was that P equaled 3.8 × 10-10 [g•cm/(cm2•day•mmHg)]. At second, we improved it by using a dew-point hygrometer. The result was that P equaled 1.4 × 10-10 [g•cm/(cm2•day•mmHg)]. We can estimate precisely a performance of waterproof layer by using second improved test and the calculation model.
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  • Yoichi Fujioka, Shigeaki Kageme, Takamasa Oshima, Kohei Ito, Kazuo Ond ...
    2002 Volume 122 Issue 12 Pages 1417-1423
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The nickel-metal hydride battery (Ni/MH) bas been developed as a power source for the hydrid electric vehicle (HEV) and the pure electric vehicle (PEV). But the larger battery with higher capacity than today's is desirable for their diffusion of HEV and PEV. The larger battery tends to have the temperature and current density distributions at its inside and the distribution deteriorates the battery's performance and life. So some simulation codes are beneficial for developing the large battery. We have studied here the thermal behavior of a small Ni/MH battery at charge cycle to develop the simulation code including the main and side reactions. The heat sources by the overpotential, the entropy change, the hydrogen occlusion and the side reaction recombination heat are measured or surveyed to model the battery. The currents for main and side reactions are also measured experimentaly with the residual oxygen by the side reaction stored in the battery. By using these data our thermal model for Ni/MH battery estimates its temperature increase during charge cycle, which is compared to the measured temperature in good agreement between them.
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  • Takayuki Wakimoto, Tatsuya Harada, Shuji Sato, Masamori Saeki, Hiroyuk ...
    2002 Volume 122 Issue 12 Pages 1424-1428
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    Impulse voltage calibration is specified in IEC 61083-1 as a reference calibration method for the digital recorder used in the impulse voltage measuring system. In the IEC publication, requirements for the impulse calibrators are also stated as having uncertainties: <±0.7% for peak value and <±2% for front time and time-to-half value. These values are, however, applied for the calibrators used in the approved measuring system. In our work, a high performance impulse calibrator, which could be used even in the national standard class measuring system as well as the reference measuring system, has been developed. The developed calibrator's performance has been evaluated to be able to generate an impulse voltage with very small uncertainties: <±0.4% for peak value and <±1.2% for front time and time-to-half value.
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  • Kohei Ito, Hiroyuki Nakaura, Shota Urushihata, Kazuo Onda
    2002 Volume 122 Issue 12 Pages 1429-1436
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    In the pulsed-discharge process, such as the thin film fabrication and the pollutant removal, the radical species produced by the electron collision with feed gas is a key factor to determine the process. So it is important to understand the radical production and consumption to develop the effective application of the pulsed-discharge process. In this study, we measured N, O and OH radical concentration by the appearance mass spectrometry. By synchronizing the acquisition of quadruple mass spectrometer signal with the pulsed-discharge, we measured the time evolution of the radical concentrations. The measured concentrations of N, O and OH radical were in the range from 1 to 1000 ppm and their concentration changed a little between the pulses of 100 Hz repetitive frequency, 3kV peak voltage and 300ns pulse width, for the mixture gas flow of N2, O2, CO2, H2O and NO at discharge tube pressure of 91Pa and room temperature. We also calculated the radical concentrations by a model, which considers Boltzmann equation for electron energy distribution and the chemical reaction rate equations for radical and stable species, adjusting the representative electric field so that the numerical power consumption per pulse is equal to the experimental. The calculated radical concentration became several orders in magnitude smaller than the experimental.
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  • Tetsuya Aoki, Nobuhito Miyauchi, Kohei Ito, Yoshitaka Inui, Kazuo Onda
    2002 Volume 122 Issue 12 Pages 1437-1446
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The performance of polymer electrolyte fuel cell is affected by the humidity of polymer electrolyte and the cell overpotentials. We have made a simulation code which is able to calculate the fuel cell generation performance in steady state. The code has been improved in the energy balance equations and in the equivalent electric circuit, compared to the previous study. In this simulation code the empirical equations for the resistive and the reactive overpotentials are adopted, which is measured at our small cell by the AC impedance meter. The numerical results by the simulation code give that the current density is high near the inlet region of fuel cell, when the inlet dew point temperatures for fuel and oxidant are higher than the cell temperature, while the current density is high near the outlet region of the fuel cell when the inlet dew point temperatures are lower than the cell temperature.
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  • Tetsuya Wakui, Takumi Hashizume
    2002 Volume 122 Issue 12 Pages 1447-1457
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    The optimal operating method of the wind turbine-generator systems matching the wind condition and wind turbine type is discussed from the viewpoint of net power extraction under field wind conditions. This paper examines three types of wind turbines: the Darrieus-Savonius hybrid turbine, the Darrieus turbine proper and the Propeller turbine. As the operating methods matching utilization of wind energy, a constant tip speed ratio operation for stand-alone power systems and a synchronous operation for utility power systems are taken up. The computed results using our dynamic simulation model show that the inherent characteristics of each wind turbine and the dynamic characteristics of the rotational components have an effect on net power extraction in the fields. Thus, we conclude that the appropriate scaling of the system and operating method exist for each wind condition and each wind turbine type.
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  • Hirohisa Ishihara, Mitsugu Watanabe, Kiyonobu Chiyajou, Koji Nagano, N ...
    2002 Volume 122 Issue 12 Pages 1458-1464
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    As a city area progresses, it becomes difficult to obtain new routes for overhead transmission lines. In order to utilize existing transmission line equipped with Aluminum conductor steel reinforced (ACSR) and increase capacity at a low cost, low-sag conductors increased in capacity such as Gap Type heat resistance Aluminum alloy conductor steel reinforced(GTACSR) are used. But the cost is rather high, and considerable time and effort is required for sagging operations of conductors.
    Therefore we developed the new type low sag conductors increased in capacity which were superior to GTACSR on the performance (capacity, reduction effect of sag). These conductors are easier to install and are at a low cost. Also we investigated the workability and accessories application, the prospects of commercialization are good.
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  • Shuichi Nogawa, Kazunari Kajimura, Minoru Kuwata, Norio Takahashi, Koj ...
    2002 Volume 122 Issue 12 Pages 1465-1472
    Published: December 01, 2002
    Released: December 19, 2008
    JOURNALS FREE ACCESS
    High harmonic currents flow in windings of power devices such as reactors for HVDC filters. In the design of such devices, the precise calculation of eddy current losses due to ac fields generated by the high harmonic current is required to control the quality factor. If the finite element method (FEM) is directly applied to the calculation of the eddy current loss in the multi-turn winding in the design of each device, it is troublesome and is not practical. In this paper, a database-oriented method is proposed. The practical estimation technique described in this paper is utilized in the design of large power filters for the HVDC project in Japan.
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