IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 125, Issue 3
Displaying 1-12 of 12 articles from this issue
Review
  • Takeshi Nagata
    2005 Volume 125 Issue 3 Pages 255-258
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    Currently, agents are focus of intense on many sub-fields of computer science and artificial intelligence. Agents are being used in an increasingly wide variety of applications. Many important computing applications such as planning, process control, communication networks and concurrent systems will benefit from using multi-agent system approach. A multi-agent system is a structure given by an environment together with a set of artificial agents capable to act on this environment. Multi-agent models are oriented towards interactions, collaborative phenomena, and autonomy. This article presents the applications of multi-agent technology to the power systems.
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Paper
  • Yuichi Saisho, Taketo Hayashi, Yasumasa Fujii, Kenji Yamaji
    2005 Volume 125 Issue 3 Pages 259-267
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    In deregulated electricity markets, the role of a distribution company is to purchase electricity from the wholesale electricity market at randomly fluctuating prices and to provide it to its customers at a given fixed price. Therefore the company has to take risk stemming from the uncertainties of electricity prices and/or demand fluctuation instead of the customers. The way to avoid the risk is to make a bilateral contact with generating companies or install its own power generation facility. This entails the necessity to develop a certain method to make an optimal strategy for electric power procurement.
    In such a circumstance, this research has the purpose for proposing a mathematical method based on stochastic dynamic programming and additionally considering the characteristics of the start-up cost of electric power generation facility to evaluate strategies of combination of the bilateral contract and power auto-generation with its own facility for procuring electric power in deregulated electricity market. In the beginning we proposed two approaches to solve the stochastic dynamic programming, and they are a Monte Carlo simulation method and a finite difference method to derive the solution of a partial differential equation of the total procurement cost of electric power. Finally we discussed the influences of the price uncertainty on optimal strategies of power procurement.
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  • Takayuki Kojima, Hiroyuki Mori
    2005 Volume 125 Issue 3 Pages 268-277
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    In this paper, a new continuation power flow method is proposed to speed up computational time for drawing P-V curves in power systems. The continuation power flow calculation aims at successively evaluating power flow solutions in changing the nodal specified value of power flow calculation. The P-V curves are useful for static voltage instability. The conventional continuation power flow calculation methods are based on the predictor-corrector method. This paper proposes a new nonlinear predictor in the predictor-corrector method. The proposed method simultaneously evaluates a set of solutions candidates through the nonlinear predictor. The effectiveness of the proposed method is demonstrated in sample systems.
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  • Toshiya Ohtaka, Shinichi Iwamoto
    2005 Volume 125 Issue 3 Pages 278-285
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    Recently, it has been considered to group distribution substations together for evaluating the reinforcement planning of distribution systems. However, the grouping is carried out by the knowledge and experience of an expert who is in charge of distribution systems, and a subjective feeling of a human being causes ambiguous grouping at the moment. Therefore, a method for imitating the grouping by the expert has been desired in order to carry out a systematic grouping which has numerical corroboration. In this paper, we propose a grouping method of distribution substations using cluster analysis based on the interconnected power between the distribution substations. Moreover, we consider the geographical constraints such as rivers, roads, business office boundaries and branch boundaries, and also examine a method for adjusting the interconnected power. Simulations are carried out to verify the validity of the proposed method using an example system. From the simulation results, we can find that the imitation of the grouping by the expert becomes possible due to considering the geographical constraints and adjusting the interconnected power, and also the calculation time and iterations can be greatly reduced by introducing the local and tabu search methods.
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  • Tomonobu Senjyu, Norihide Sueyoshi, Ryo Kuninaka, Katsumi Uezato, Hide ...
    2005 Volume 125 Issue 3 Pages 286-292
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    This paper deals with two types of control method concerning induction generator used in wind power generating station. One is aiming at keeping the voltage magnitude of the node of the station and the other is aiming at keeping the constant power factor through the branch connecting to the station. Both of them are able to be in controllable area by adjusting generator reactive power using compensating capacitor. At first, the theoretical equations expressing terminal voltage and power factor for induction generator are derived, and then the compensating capacitor corresponding to the wind velocity variation is determined quantitatively. By using the proposed control method, it is confirmed to be able to keep the terminal voltage and operating power factor of wind power generation system to a target value even in the case when the abrupt deviation is caused by wind power disturbance.
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  • Ken Furusawa, Hideharu Sugihara, Kiichiro Tsuji, Yasunori Mitani
    2005 Volume 125 Issue 3 Pages 293-301
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    In recent years, energy storage systems have increasingly been expected as a means of load leveling of the annual load factor. Of course it has an effect to install the energy storage systems at the substation. But some customers operate their storage system integrately and it also has an effect to increase load factor. In this paper the authors proposed a method that the energy storage systems at customer side are used for a congestion relief on transmission networks. However, it is not clear that which kind of customers has the effect of relieving transmission line congestion. First of all, this paper assumes the authors determine the optimal configuration of energy equipment including energy storage system. We propose the new cotract that electric utility subsidizes a part of the entrance cost of the energy storage systems and customers change the output pattern of energy storage according to the request of the electric utility. This paper evaluates the possibility that the contract gives merit to both the electric utility and the customer.
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  • Tadahiro Itagaki, Hiroyuki Mori
    2005 Volume 125 Issue 3 Pages 302-308
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    This paper presents a new preconditioned method for short-term load forecasting that focuses on more accurate predicted value. In recent years, the deregulated and competitive power market increases the degree of uncertainty. As a result, more sophisticated short-term load forecasting techniques are required to deal with more complicated load behavior. To alleviate the complexity of load behavior, this paper presents a new preconditioned model. In this paper, clustering results are reconstructed to equalize the number of learning data after clustering with the Kohonen-based neural network. That enhances a short-term load forecasting model at each reconstructed cluster. The proposed method is successfully applied to real data of one-step ahead daily maximum load forecasting.
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  • Boonruang Marungsri, Hidenori Komiya, Hiroyuki Shinokubo, Ryosuke Mats ...
    2005 Volume 125 Issue 3 Pages 309-314
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    Salt fog ageing tests are widely conducted for evaluating anti-tracking/anti-erosion performance of housing materials for outdoor polymer insulators. A detailed test method, however, is not yet standardized and round robin tests have been conducted for standardization all over the world. Here we have investigated the effect of fog conditions on the deterioration of silicone rubber under two different salt fog conditions generated by an ultrasonic humidifier and an IEC nozzle. In spite of the same injection rate and the same salinity, comparable results from the viewpoints of leakage/discharge currents and the degree of surface deterioration could not be obtained between the two salt fog conditions generated by the ultrasonic humidifier and the IEC nozzle. Almost comparable test results, however, were obtained under the two salt fog conditions generated by the ultrasonic humidifier and the IEC nozzle after controlling the salt fog particle size distribution.
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  • Toshiaki Rokunohe, Fumihiro Endo, Yoshio Yoshida, Yoshihiko Nakagoe, M ...
    2005 Volume 125 Issue 3 Pages 315-321
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    The newest GIS is being reduced in size due to advances in arrester performance and reduction of impulse test voltage for specifications. Field strength of the inner surface for the GIS tank is being strengthened more than ever; for this, it is necessary that the design work consider particles included in the GIS. When GCB and DS are opened, residual DC voltage occurs at the conductor between the GCB and DS. Movement of particles under DC voltage is known to differ from that under AC voltage. It is very important to know particle movement under DC voltage, even if the GIS is for AC use. Therefore, this paper deals with particle-levitation under DC voltage in SF6 gas. Effects of polarity and vibration were confirmed for levitation of a particle on an insulated coating electrode. An aluminum particle (φ0.25×L3) on a sheath of 0.5MV/m did not levitate until a 6.5G oscillation acceleration was reached under a single-polarity DC voltage. On the other hand, the particle levitated at about a 2G oscillation acceleration under a reversed polarity DC voltage. Moreover, oscillation acceleration of initial levitation for a large size GIS model was almost equal with that of fundamental experiments.
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  • Tadao Minagawa, Eiichi Nagao, Ei Tsuchie, Hiroshi Yonezawa, Daisuke Ta ...
    2005 Volume 125 Issue 3 Pages 322-330
    Published: 2005
    Released on J-STAGE: June 01, 2005
    JOURNAL FREE ACCESS
    Owing to increasing number of highly aged GIS, the investigation of the remaining lifetimes of those systems are becoming more important. Because a lot of O-rings are used in GIS, the study of degradation mechanism and lifetime estimation method of O-ring is essential. In this paper, the information about O-ring degradation mechanism is described, and the statistical method for estimating the remaining lifetime of O-ring is proposed. The degradation of O-ring is mainly subject to chemical reactions triggered by oxygen. Because there are many factors influencing those chemical reactions, the dispersion of degradation rates of O-rings in GIS is very large. Consequently the statistical analysis is one of the effective techniques for lifetime estimation of O-rings in GIS.
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