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Volume 129, Issue 7
Displaying 1-14 of 14 articles from this issue
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Review
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Kazuhito Oishi, Yukinari Fukumoto2009 Volume 129 Issue 7 Pages 851-854
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSOffshore wind energy has been widely exploited in Europe. Having a long coastline, the offshore wind energy will be the one of the important solutions for the increase of renewable energy in Japan. However, due to the difference in wind and marine condition between Japan and Europe, the safety, the environmental impact and the economical feasibility of the offshore wind power generation system have to be investigated in Japan. According to the data observed offshore, the wind speed is enough higher than that on land and the wind energy is economically feasible. In order to utilize the energy, the design method of the foundation against very high waves in typhoon storm should be established. For shallow offshore coastal area, gravity foundation type has been improved by hydraulic experiment. Additionally, for deeper ocean, floating types such as semi-submersible float and spar-buoy have been researched.View full abstractDownload PDF (1647K)
Essay
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Masatoshi Takeda2009 Volume 129 Issue 7 Pages 855-858
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSThe self-commutated Static Var Compensator (STATCOM) is expected as one of the most effective tools to enhance power system stability and has been applied world-widely in recent years. Since the first prototype of STATCOM was developed in Japan in 1980, continual efforts by utilities and manufactures drove the development forward to the practical application of STATCOM, resulting in the world-first application of 80MVA STATCOM using GTO thyristors in 1991, followed by the 80MVA STATCOM using GCT thyristors in 2003. Since then, the application of STATCOM has been extended to not only power utility systems but also industrial systems. This paper describes historical development events and engineer's efforts to develop the STATCOM, including some episodes.View full abstractDownload PDF (1247K)
Paper
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Yasuo Shigemori, Atsushi Ishigame, Osamu Yatsubo, Takeshi Kawaguchi2009 Volume 129 Issue 7 Pages 859-868
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSA more flexible operation of electric power system is needed along with a progress of the electric power deregulation and an increase of the interconnected dispersed generation. Voltage and reactive power control (VQC) that aims to maintain especially voltage within the range of regulations, and to maintain the electric power quality is expected to become more and more important for high-performance system operation.
In this paper, we propose a new technique of VQC considering time lag of voltage control device with the short-term load forecasting and the optimal control by Particle Swarm Optimization (PSO).View full abstractDownload PDF (1575K) -
Shunsuke Tanaka, Hirokazu Suzuki2009 Volume 129 Issue 7 Pages 869-879
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSWhen many distributed generators (DGs) are connected to a distribution line, the upward power flow from DGs causes the difficulty in line voltage regulation. As the countermeasure, we propose several methods to control line voltages by use of DGs' reactive power outputs. Every proposed method using only DGs themselves is implemented in an autonomous decentralized way. So, these methods are distinguished from the other methods using power system apparatus in the centralized control over the power system. DGs with the function to estimate the line impedance provide the power system with reactive power according to the estimated impedance value, and regulate the line voltages. We evaluate the effect of the proposed methods for voltage compensation by simulation studies in two types of distribution system models.View full abstractDownload PDF (1927K) -
Takuya Yamazaki, Rion Takahashi, Toshiaki Murata, Junji Tamura, Tomoyu ...2009 Volume 129 Issue 7 Pages 880-888
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSAs wind turbine output is proportional to the cubic of wind speed, the wind turbine generator output fluctuates due to wind speed variations. Hence, if the power capacity of wind power generators becomes large, wind power generator output can have an influence on the power system frequency. Some methods for smoothing the wind generator output fluctuations using several types of energy storage systems have been proposed, however, these methods have a cost problem. This paper proposes a new pitch control system for smoothing the wind generator output fluctuations.View full abstractDownload PDF (2595K) -
Yicheng Zhou, Moritoshi Kato, Naoki Saitou, Ryuichi Yokoyama2009 Volume 129 Issue 7 Pages 889-896
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSEvaluation of the mean life of equipments is a basic issue for effective equipment maintenance. This paper presents a method to estimate the mean life and its standard deviation of power system equipments with limited end-of-life failure data. We propose a model using 3-parameter Weibull distribution based on the results Li (2004) produced. It is assumed that the mean life of power equipments consists of “non end-of-life failure period” and “period of aging end-of-life failure”, which is represented by a location parameter of Weibull distribution. Three parameters of Weibull distribution are estimated by applying Levenberg-Marquardt method, which is one of the optimization algorithms. The computational procedures of non-linear regression, which take account both of good convergence and practical use, are proposed. Numerical examples show that our model better fits to actual data than 2-parameter Weibull distribution model.View full abstractDownload PDF (1119K) -
Yuya Takeuchi, Hajime Miyauchi, Toshihiro Kita2009 Volume 129 Issue 7 Pages 897-904
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSRecently, deregulation and reform of electric power utilities have been progressing in many parts of the world. In Japan, partial deregulation has been started from generation sector since 1995 and partial deregulation of retail sector is executed through twice law revisions. Through the deregulation, because electric power is traded in the market and its price is always fluctuated, it is important for the electric power business to analyze and predict the price. Although the price data of the electric power market is time series data, it is not always proper to analyze by the linear model such as ARMA because the price sometimes changes suddenly. Therefore, in this paper, we apply the methods of chaotic time series analysis, one of non-linear analysis methods, and investigate the chaotic characteristics of the system price of JEPX.View full abstractDownload PDF (1015K) -
Teru Miyazaki, Yoshiki Sakamoto, Shigemitsu Okabe, Kenjirou Mori, Jun ...2009 Volume 129 Issue 7 Pages 905-913
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSThis paper has experimentally studied a simulation method for estimating a lightning outage rate of distribution lines. The observation shows that direct lightning hits to distribution systems are the main cause of the outage of the line, and further suggests that the two factors, the installation rate of surge arresters and the density of the lines, can play a decisive role in the generation of a direct lightning stroke to the line. Based on these data, a computer program was proposed to estimate a lightning outage rate due to lightning strokes, and the calculated results showed good agreement with the observed values in the actual lines. These results suggest that the method can contribute to the evaluation of lightning protection devices such as shielding wires and surge arresters, and can lead to effective lightning protection practices.View full abstractDownload PDF (2195K) -
Yoshiki Sakamoto, Teru Miyazaki, Shigemitsu Okabe2009 Volume 129 Issue 7 Pages 914-920
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSThe numbers of damages of home electric appliances due to lightning surges have recently increased. Installing Surge Protective Devices (SPDs) for indoor distribution line is one of countermeasures against the damages, and is also spreading after an amendment of the regulation on indoor wires in 2005. Past studies have showed that the SPDs installed on the switchboard are effective for protecting all the equipment supplied by indoor distribution lines against lightning strokes.
However, it is difficult to evaluate the protective effects of the SPDs against lightning strikes when considering complex indoor wires in houses. Thus, a high-precision analysis method is required to clarify the lightning performance of the SPDs for interior wiring. In this research, experiments were conducted to grasp the protective effects of the SPDs installed on a switchboard against lightning surges invading into a house, and an analysis model by the EMTP was proposed. The calculated results relatively agreed with the experimental results.View full abstractDownload PDF (1575K) -
Shin-ichi Tanaka, Toshiro Matsumura2009 Volume 129 Issue 7 Pages 921-928
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSA simulation model for the column behavior on the long gap free arcs in air was constructed. In this model, the current path of the arc column was assumed to be a string of many nodes separated by very short intervals. Concerning the operation of the nodes, we considered the continuous motion due to the Lorentz force and the instantaneous motion due to the partial shorting, and introduced two special parameters to control them. One parameter was used to control the velocity of the continuous motion of the arc column, while the other was used to control the occurrence frequency of the partial shorting on the arc column. To evaluate the validity of the constructed simulation model, the column behaviors on DC free arcs with currents of 100, 500 and 2000A respectively on a gap length of 1.6m were simulated with giving various values to two special parameters. Consequently, it was proved that the simulation results with certain suitable values on two special parameters showed similar column behaviors to the actual characteristics, and that the constructed simulation model was valid.View full abstractDownload PDF (1348K) -
Mikihisa Saito, Masaru Ishii, Hironao Kawamura, Takatoshi Shindo2009 Volume 129 Issue 7 Pages 929-934
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSNegative upward lightning flashes from a high structure in winter were observed by a current shunt and a network of VHF receivers, slow antennas and fast antennas on the coast of the Sea of Japan. VHF radiation sources associated with the lightning discharges were located three-dimensionally by the TOA method. Continuing currents of 6 upward lightning flashes were observed, and the position and the amount of associated charges in clouds were estimated from the data of the observation network. The measured charge amounts by the current shunt and the estimated neutralized charge amounts from electric field observation show good agreement.View full abstractDownload PDF (969K) -
Tadashi Koshizuka, Takeshi Shinkai, Keisuke Udagawa, Hiromichi Kawano2009 Volume 129 Issue 7 Pages 935-940
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSThis paper shows the simulation of SLF interrupting performances for SF6 gas circuit breakers. From the measurements using 300kV-SF6 gas model circuit breakers, it was shown that the extinction peak voltages were varying with arcing times. But, the current values at the extinction peak were the same.
To simulate the SLF interrupting performances for the circuit breakers, serially connected 3 arc models were used. Cassie arc model and two Mayr arc models were serially connected. In this arc model, the Cassie model simulates the high current arc. One of the Mayr arc model (Mayr model 1) simulates the arc around the voltage extinction peak. And the other Mayr arc model simulates the arc around current zero. In this model, arc voltage of the Cassie model and arc power loss of the Mayr model 1 are only estimated from the experiments. It was good agreement with the measurements and simulations.View full abstractDownload PDF (1758K) -
Satoru Miyazaki, Hisashi Goshima, Hiroyuki Shinkai, Masafumi Yashima, ...2009 Volume 129 Issue 7 Pages 941-947
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSLong-term stability of step-response parameters of the standard voltage divider may be useful in evaluating the long-term stability of the standard measuring system for high voltage impulse, which influences the uncertainty of the system . Because dispersions of the step-response parameters have been large, they have not been considered in evaluating the uncertainty of the system. Dispersion of the experimental response time is largely due to noise superimposed on measured step-response waveforms. It can be reduced either by increasing sampling rates of the waveform or by improving the signal to noise (S/N) ratio. Dispersion of the partial response times is due to oscillations on the wavefront of step-response waveforms. Calculation of the virtual origin becomes unstable in the presence of the oscillation, resulting in the dispersion of the partial response time.View full abstractDownload PDF (972K) -
Takumi Matsuda, Yoshihiro Baba, Naoto Nagaoka, Akihiro Ametani2009 Volume 129 Issue 7 Pages 948-956
Published: July 01, 2009
Released on J-STAGE: July 01, 2009
JOURNAL FREE ACCESSIn this paper, fundamentals of the transmission-line-modeling or matrix (TLM) method are briefly explained. Then, it is applied to analyzing transient electromagnetic fields produced by a current wave propagating along a simulated vertical lightning return-stroke channel, and surges on a simple conductor system. In both applications, the TLM-calculated field and surge waveforms agree well with the corresponding waveforms calculated theoretically and/or using the finite-difference time-domain method.View full abstractDownload PDF (815K)
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