IEEJ Transactions on Power and Energy
Online ISSN : 1348-8147
Print ISSN : 0385-4213
ISSN-L : 0385-4213
Volume 136 , Issue 3
Showing 1-31 articles out of 31 articles from the selected issue
Review
  • Mikimasa Iwata
    2016 Volume 136 Issue 3 Pages 224-227
    Published: March 01, 2016
    Released: March 01, 2016
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    When a fault arc occurs in an electrical installation, the pressure in it increases due to the energy input from the arc into the gas. With surrounding equipment and personnel safety in mind, the properties of the pressure rise and propagation must be clarified. For this purpose, internal arc tests for electrical installations have been carried out. However, the testing conditions are so wide ranging that a lot of effort and cost will have to be consumed. Since this is inefficient, it is desirable to find a way to calculate the pressure rise and propagation. This paper describes the trend of calculation technology of pressure rise and propagation in electrical installations due to fault arcs, where the arcs are generated in air or SF6 or oil that is the main insulating material in electrical installations.
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Paper
  • Kota Ishikawa, Wataru Kitagawa, Takaharu Takeshita
    2016 Volume 136 Issue 3 Pages 228-235
    Published: March 01, 2016
    Released: March 01, 2016
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    This paper presents a multi-objective optimization using genetic programming (GP). In this method, an analysis model is regarded as a tree structure. This tree structure is divided into polygons and material information. Therefore, this method can be applied GP. Additionally, authors take into consideration about shape complexity. The target of electromagnetic device is an interior permanent magnetic synchronous motor (IPMSM). This method optimizes flux barriers in IPMSM by two-dimensional finite element method (2D-FEM). The purpose of this paper is an investigation of design optimization by multi-objective optimization. Authors reveal the pareto optimal solutions of characteristics for average torque and torque ripple of IPMSM.
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  • Kenichi Kawabe, Issei Matsuda, Kazuyuki Tanaka
    2016 Volume 136 Issue 3 Pages 236-244
    Published: March 01, 2016
    Released: March 01, 2016
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    Currently, Japanese grid codes require photovoltaic (PV) power generation systems to continue supplying power to the grid as soon as possible even if the systems temporarily stop their operation. Although the fault ride-through (FRT) capability was originally proposed for preventing a cascading frequency drop in the power system, the capability has the impact on other instability phenomena such as transient stability. In this study, we focus on the post-fault active power recovery of the PV systems. The impact of the recovery speed on the transient stability is investigated under different load conditions, static/dynamic load condition. Numerical examples are carried out for the one-machine one-load infinite-bus system, and the effects of the recovery speed are evaluated by equal area criterion and critical clearing time. As a result, we have found both desirable and undesirable effects on the transient stability depending on the load condition.
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  • Yusuke Miyamoto, Yasuhiro Hayashi
    2016 Volume 136 Issue 3 Pages 245-258
    Published: March 01, 2016
    Released: March 01, 2016
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    Recently home energy management system (HEMS) has been spread due to increase in awareness of save energy after Great East Japan Earthquake. HEMS consists of photovoltaic power system (PV), battery energy storage system (BESS) and heat pump water heater (HPWH), etc. Residential PV implementation rate has been increasing due to feed in tariff from 2009. So there is a danger of output suppression loss due to voltage increase on a distribution line due to reverse power flow from each residential PV. So we try to study how to reduce output suppression loss using BESS and HPWH optimally. One of the main purpose to implement BESS and HPWH is for economy using the difference in electricity charges between during nighttime and daytime. So in this research, we optimize how to operate BESS and HPWH to improve the benefit of the electric power selling charges and electricity charges considering reduction of output suppression loss and the difference in electricity charges between during nighttime and daytime.
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  • Shuhei Kawamura, Hiroumi Saitoh
    2016 Volume 136 Issue 3 Pages 259-267
    Published: March 01, 2016
    Released: March 01, 2016
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    Output fluctuation of renewable energy generation such as wind power generation can lead to extend of tie line flow fluctuation. Therefore, power system transient stability may deteriorate. On the other hand, adjustable speed pumped storage generators have high speed adjusting output capability by ac excitation control with power electronic equipment having high response speed. This paper proposes output control of adjustable speed pumped storage generators using power flow fluctuation to enhance transient stability by suppression fringe component of tie line flow fluctuation. The feature of this control method is that, if transient stability is deteriorated by fringe component of power flow fluctuation, adjustable speed pumped storage generators choose fringe suppression control. Otherwise, adjustable speed pumped storage generators choose load frequency control. In order to check the effectiveness of the propose approach, numerical simulations are conducted on the interconnected 2-area power system model. The result shows that the proposed approach can suppress fringe component of tie line flow fluctuation and enhance transient stability.
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  • Akiko Takahashi, Tomohisa Makino, Jun Imai, Shigeyuki Funabiki
    2016 Volume 136 Issue 3 Pages 268-274
    Published: March 01, 2016
    Released: March 01, 2016
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    This paper proposes a novel method for the short-term prediction of photovoltaic generation (PV) power using difference vectors. The predicted data are used for the smoothing control of PV power fluctuation with the moving average method in order to reduce the capacity of the energy storage device. Three smoothing control methods are discussed in this paper: a persistence method, a local fuzzy reconstruction method, and the proposed method for prediction, respectively. The results of the smoothing control methods are evaluated in terms of the prediction error, reduction rate of fluctuation, power in load frequency control (LFC) band, and capacity of the energy storage device. The proposed method has the lowest prediction error among the three methods. Furthermore, the smoothing control scheme with the function of managing the stored energy is advantageous in that it can reduce the capacity of the energy storage device by approximately 44% compared to a smoothing control scheme without the abovementioned function.
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  • Mohd Shahrin, Hidenori Aoki
    2016 Volume 136 Issue 3 Pages 275-283
    Published: March 01, 2016
    Released: March 01, 2016
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    The problem of recovery from power-system failures is the problem of handling operations that make it possible to supply power from other lines in response to power-system failures or construction by switching between the opened and closed states of sectionalizing switches. Considerable research has already been conducted with regard to this issue. This paper addresses the issue of determining target systems for final recovery in cases when some sections remain subject to power failure (i.e., sound bank capacity < load capacity). For this purpose, this paper proposes the study of Genetic Algorithm (GA) that applied multi-objective optimization called Non-dominating Sorting Algorithm GA-II (NSGA II) which able to solve the problem of weighting factor method. Furthermore, from the comparison to other references, the effectiveness of this proposed method with small and large scale network is shown.
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  • Ken-ichiro Nishio, Kenta Ofuji
    2016 Volume 136 Issue 3 Pages 284-290
    Published: March 01, 2016
    Released: March 01, 2016
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    In this paper, we studied differences in the electricity saving rates across households, observed in the summer months of July through September after the Great East Japan Earthquake. To explain what factors carry different influences on the electricity saving rates, we ran panel data regression models using the electricity consumption billing data in the summer months, July through September, over the five years of 2010-2014 for 910 households in the Tokyo and Kansai areas. Specifically, we concentrated on two main explanatory factors: household attributes that include household size and income, and electricity consumption tendencies characterized by average consumption level and its standard deviation. We found that, while some household attributes such as age and floor space have statistically significant linear relationships with the saving rates, households with higher average consumption can have higher saving rates, implying the electricity consumption data acquired by smart meters may be among the key determinants for tailored energy-saving recommendations.
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  • Jun Yoshinaga, Satoru Akagi, Masakazu Ito, Yasuhiro Hayashi, Kazunari ...
    2016 Volume 136 Issue 3 Pages 291-301
    Published: March 01, 2016
    Released: March 01, 2016
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    Voltage deviation in distribution networks and photovoltaic (PV) output restriction, caused by a large amount of PV systems installation, have been issued recently. BESS (Battery Energy Storage System) is one of the solutions. However, the detailed evaluation of the voltage control effect of BESS has not been carried out, because its effect varies according to BESS placement, its output and configuration of distribution, etc. Therefore, the amount of PV introduction limits in several distribution networks were evaluated and effective BESS arrangement and output control were examined in this paper. The effectiveness of the proposed BESS cooperating voltage control method with LRT, SVR was verified using numerical simulation and experiment of distribution system simulator.
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  • Seiji Yonezawa, Satoshi Takayama, Atsushi Ishigame, Takaharu Ito, Kats ...
    2016 Volume 136 Issue 3 Pages 302-310
    Published: March 01, 2016
    Released: March 01, 2016
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    Recent years, installation of Photovoltaic (PV) system to power system is active by the environmental problem, feed in tariff system and decrement of initial investment cost. Now, the distribution system is already controlled by the existing voltage controller. However, voltage deviation is caused by high penetration of PV. In order to reduce the effect of PV power fluctuation, the Static Var Compensator (SVC) is planning to install in distribution system. SVC offers a high-speed voltage control. But there is a possibility SVC cannot operate effectively by the difference of a working speed between SVC and existing voltage controllers. So the installation of effectively SVC is required to operate cooperatively with existing voltage controllers. In this research, the automatic voltage control technique of the distribution system by SVC which used the moving average control is proposed. Since the setting value of SVC is updated by the moving average, compared with the conventional SVC control technique, an effective and efficient voltage control is given by the proposed the automatic voltage control technique of SVC.
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  • Shinji Yamamoto, Toru Iwao
    2016 Volume 136 Issue 3 Pages 311-317
    Published: March 01, 2016
    Released: March 01, 2016
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    The high ambient pressure is important for surface treatment on the metal surface using the vacuum arc cathode spot because the cost becomes low, and the equipment becomes simple. However, the effects of ambient pressure on the physical process, surface roughness, and removal of the oxide layer remain unclear. The surface roughness might be derived from the removal area speed of oxide layer and evaporation rate. Consequently, the evaporation rate of the vacuum arc cathode spot as affected by ambient pressure is important to ascertain the removal process. This study elucidated the evaporation rate of the vacuum arc cathode spot as it is affected by ambient pressure. The mean number, split frequency, removal area speed, and mean current density were measured experimentally with changes in ambient pressure. In addition, the evaporation rate and temperature distribution are calculated using heat conduction simulation of the oxide layer, bulk, and ambient gas. Experiments were conducted using an SS400 cathode and a cylindrical copper anode. A high-speed video camera recorded the cathode spot movement. Then, the obtained images were analyzed using plasma image processing. Heat conduction was calculated using the energy conservation equation. The mean number, split frequency, removal area speed, and mean current density of cathode spots decrease concomitantly with increasing ambient pressure. The evaporation rate mostly increases concomitantly with increasing speed of the cathode spot movement, i.e., the low ambient pressure and small cathode spot area. The evaporation rate depends on the power density and the specific heat and thermal conductivity of the material. Therefore, the evaporation rate is derived from the stagnation time and the cathode spot temperature, and also from the current density and cathode spot area.
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  • Naoya Miyamoto, Makoto Koizumi, Hiroshi Miyao, Takayuki Kobayashi, Koj ...
    2016 Volume 136 Issue 3 Pages 318-324
    Published: March 01, 2016
    Released: March 01, 2016
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    The flow electrification phenomenon is known as a major cause of failures in oil-cooled power transformers. To improve the reliability of transformers, we need to be able to predict the electric field caused by flow electrification in a transformer. We developed a three-dimensional (3D) flow electrification simulation model to predict the wall current distributions in complex-shaped pressboard ducts that produce complicated oil flows. First, we derived a flow electrification analysis model, which reflects the correlation between local wall current density and local wall shear stress. This analysis model was verified by measured data of wall current density generated in a straight pressboard duct. Then, we applied this analysis model to 3D simulation code and simulated flow electrification in two types of channel structure, a T junction structure and a narrow oil gap structure, which represent typical structures that often appear in real transformers. We compared the simulation results with the measurement results and confirmed that the prediction accuracy of the simulation code is at the practical level for estimating flow electrification in a transformer.
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  • Toshiya Ohtaka, Tomo Tadokoro, Masashi Kotari, Mikimasa Iwata, Tadashi ...
    2016 Volume 136 Issue 3 Pages 325-332
    Published: March 01, 2016
    Released: March 01, 2016
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    When a fault arc occurs in electric power equipment including insulation oil, it may cause damage to the equipment resulting from a rapid pressure rise, and lead to leakage and blowout of the oil and the generation of a high-temperature flammable pyrolysis gas. Therefore, we have examined these phenomena for an underwater arc from experimental and simulation aspects, as a preliminary step toward dealing with an arc in the oil. In this study, we have developed a pressure rise analysis method taking into account the thermodynamic behavior for the underwater arc by improving the previous work focused on the hydrodynamic behavior of gas-liquid two-phase flow, and verified the validity of the analysis method by comparing the experimental and simulation results.
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  • Takashi Kurihara, Eiji Tsutsui, Eiji Nakanishi, Kiyoshi Maki, Kenichi ...
    2016 Volume 136 Issue 3 Pages 333-343
    Published: March 01, 2016
    Released: March 01, 2016
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    Dry-cured and extruded three-layer (E-E type) 6.6kV cross-linked polyethylene (XLPE) cables were introduced into electric power systems more than 30 years ago, but they do not experience failures because of water tree degradation. Also, the degradation index of water treeing for these cables has not been established. Therefore, investigating results of residual breakdown voltage and water tree degradation of these cables will help us plan for cable replacement and determine water tree degradation diagnosis scheduling, and will be fundamental data for cable lifetime evaluation. In this study, the authors measured the AC breakdown voltages of dry-cured and E-E type 6.6kV XLPE cables removed after 18-25 years of operation and observed the water trees in their XLPE insulation. As a result, it was observed that breakdown voltages were larger than the maximum operating voltage (6.9kV) and the AC voltage for the dielectric withstanding test (10.3kV). Water trees were mainly bow-tie water trees and their maximum length was approximately 1mm. Although the number of measured cables was limited, the lifetime of this type of cable was estimated to be approximately 40 years, even experiencing water immersion.
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  • Li Lu, Tomohiro Moriyama, Satoshi Ichimura, Yasutomo Saito, Akira Yama ...
    2016 Volume 136 Issue 3 Pages 344-350
    Published: March 01, 2016
    Released: March 01, 2016
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    A demonstration system for detecting and visualizing a small amount of oil leakage from a transformer was developed. The system uses a method of detecting fluorescence emitted from oil when it is irradiated by black light. Image processing using the relationship between saturation and intensity in a hue-saturation-intensity color space is used for recognizing the oil leakage from the background in the image obtained by the black-light irradiation. According to the saturation-intensity relationship, the intensity of a surface without oil adhesion linearly increases as saturation increases. Points on the surface of a plate flange (representing the surface of the transformer) belonging to the oil showed higher intensity than that of the surface without oil adhesion. An algorithm for automatically setting a threshold value line to recognize the oil, considering the distribution range of the intensity at each saturation value, was constructed. The developed system using this algorithm can detect and visualize oil leakage from a transformer at an amount of less than 1mL.
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