• Title, Summary, Keyword: Distribution systems

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Evaluation of Interconnection Capacity of SCOGNs to the power Distribution Systems from the Viewpoint of Voltage Regulation (전압조정 측면에서 본 소형 열병합발전 배전계통 도입량 평가)

  • 최준호;김재철
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.9
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    • pp.1096-1102
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    • 1999
  • This paper discusses the evaluation of interconnection capacity of small cogeneration(SCOGN) systems to the power distribution systems from the viewpoint of voltage regulation. Power utilities are required to keep the customers' voltage profile over a feeder close to the rated value under all load conditions. However, it is expected that the interconnection of SCOGNs to the power distribution systems impacts on the existing voltage regulation method and customers' voltage variations. Therefore, SCOGNs should be integrated to the automated power distribution systems to prevent interconnection problems and supply high quality electricity to the customers. For these reasons, we should proceed with the evaluation of interconnection capacity of SCOGNs to the power distribution systems. However, it is generally impossible to perform actual testing on the power distribution systems, and standardized methodologies and guidelines are not developed to evaluate it. The criterion indexes for voltage regulation and variations are presented in order to evaluate the interconnection capacity of SCOGNs to the power distribution systems. In addition, the evaluation methodology of interconnection capacity of SCOGNs for power distribution systems is presented. It is expected that the resulted of this paper are useful for power system planners to determine the interconnection capacity of SCOGNs and dispersed storage and generation (DSG) systems to the power distribution systems.

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Design of Physical Distribution Cost Information Systems of Manufacturing Enterprises (제조기업의 물류원가정보시스템의 설계)

  • 김동석
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.18 no.33
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    • pp.161-171
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    • 1995
  • When physical distribution cost can be correctly measured, its management can also be efficient. Thus the primary objective of the study is to develop systems for measuring correctly physical distribution cost. The systems have two aspects : the One is the consumption of the resourses(materials, labor service, the other services), the other is the creation of physical distribution services(transportation, storage, cargo, packing, distribution conversion, management). By measuring the cost through the systems, the commoditization of the physical distribution services is possible and measurement of the cost and revenue can also be reasonable ,which makes its management efficient.

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A Study on the Lightning Overvoltage Analysis and Lightning Surge Protection Methods in 22.9kV Underground Distribution Systems (22.9kV 지중계통의 뇌과전압 해석 및 뇌서지 보호방안에 관한 연구)

  • 김상국;정채균;이종범;박왈서
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.8
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    • pp.454-460
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    • 2004
  • The effects of surge arresters for protection of transmission systems against direct lightning strokes have already been reviewed using Electromagnetic Transients Program(EMTP). Distribution lines are spanned in much larger area than transmission lines, and therefore, are more susceptible to lightning strokes. We have modelled the 22.9kV underground distribution cable systems that have arresters and grounding wires. And this paper analyzes the overvoltages on underground distribution cable systems when direct lightning strokes strike on the overhead grounding wire using EMTP. Then we investigated that (1) the effects of lightning stroke according to underground distribution cable length (2) voltages at the riser pole and at the cable terminal according to installation of arrester. This study will provide insulation coordination methods for reasonable systems design in 22.9kV underground distribution cable systems.

A Study for the Voltage Analysis Method of Distribution Systems with Distributed Generation (분산전원이 도입된 배전계통의 전압해석 방법에 관한 연구)

  • 김태응;김재언
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.52 no.2
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    • pp.69-78
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    • 2003
  • This paper presents a voltage analysis method of distribution systems interconnected with DG(Distributed Generation). Nowadays, small scale DG becomes to be introduced into power distribution systems. But in that case, it is difficult to properly maintain the terminal voltage of low voltage customers by using only ULTC(Under Load Tap Changer). This paper presents a voltage analysis method of distribution systems with DC for proper voltage regulation of power distribution systems with ULTC. In order to develop the voltage analysis method, distribution system modeling method and advanced loadflow method are proposed. Proposed method has been applied to a 22.9 kV practical power distribution systems.

A Study on the Optimal Investment Method for Distribution Systems Interconnected with Dispersed Generations (분산전원이 연계된 배전계통의 최적 설비투자 방안에 관한 연구)

  • Rho, Dae-Seok
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.12
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    • pp.2179-2185
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    • 2008
  • This paper deals with the optimal investment method for distribution facilities, based on the analytical approach for the reliability assessment in distribution systems interconnected with new dispersed generations. The existing approach can estimate the expected reliability performance of distribution systems by a direct assessment of the configuration of the systems using the reliability indexes such as NDP(Non-Delivery Power) and NDE(Non-Delivery Energy). The indexes can only consider the number and configuration of the load, but can not consider the characteristics of the load which is the one of the most important factor in the investment cost for the distribution systems. Therefore, this paper presents the new performance indexes for the investment of the distribution facilities considering both the expected interruption cost for the load section and the operation characteristics of dispersed generations. The results from a case study show that the proposed methods can be a practical tool for the voltage management in distribution systems including dispersed sources.

Economic Evaluations of Secondary Battery Energy Storage Systems in Power Distribution Systems (전력저장전지시스템의 경제성 평가)

  • No, Dae-Seok;O, Yong-Taek
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.4
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    • pp.152-160
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    • 2000
  • This paper presents an efficient evaluation method on the role of new energy storage systems, especially the secondary Battery Energy Storage (BES) systems, in the case where they are interconnected with the power distribution systems. It is important to perform the economic evaluation for the new energy storage systems in a synthetical and quantitative manner, because they are very costly in the early stage of their development and commercialization. In this paper, the multiple functions of BES systems, which are operated at distribution systems, such as load levelling, effective utilization of power distribution systems and uninterruptible power supply at the emergency conditions are classified and analyzed. And then the quantitative evaluation methods of the multiple functions for BES systems are proposed using the mathematical modelling.

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Constant DC Capacitor Voltage Control based Strategy for Active Load Balancer in Three-phase Four-wire Distribution Systems

  • Win, Tint Soe;Tanaka, Toshihiko;Hiraki, Eiji;Okamoto, Masayuki;Lee, Seong Ryong
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.2
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    • pp.176-183
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    • 2014
  • Three-phase four-wire distribution systems are used for both three-phase three-wire loads and single-phase two-wire consumer appliances in South Korea, Myanmar and other countries. Unbalanced load conditions frequently occur in these distribution systems. These unbalanced load conditions cause unbalanced voltages for three-phase and single-phase loads, and increase the loss in the distribution transformer. In this paper, we propose constant DC capacitor voltage control based strategy for the active load balancer (ALB) in the three-phase four-wire distribution systems. Constant DC capacitor voltage control is always used in active power line conditioners. The proposed control strategy does not require any computation blocks of the active and reactive currents on the distribution systems. Balanced source-side currents with a unity power factor are obtained without any calculation block of the unbalanced active and reactive components on the load side. The basic principle of the constant DC capacitor voltage control based strategy for the ALB is discussed in detail and then confirmed by both digital computer simulations using PSIM software and prototype experimental model. Simulation and experimental results demonstrate that the proposed control strategy for the ALB can balance the source currents with a unity power factor in the three-phase four-wire distribution systems.

Analysis of Effect on the Transient State According to Common Grounding between Underground Transmission Systems and Distribution Systems (지중송전 및 배전계통의 공통접지에 따른 과도상태 영향 분석)

  • Lim, Kwang-Sik;Lee, Jong-Beom
    • Proceedings of the KIEE Conference
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    • pp.740-741
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    • 2007
  • This paper analyses the transient state of underground distribution system against single line to ground fault in underground transmission systems, when underground transmission systems and distribution systems are made of common grounding. Underground transmission systems and distribution systems are modeled by EMTP/ATPDraw. Simulation is carried out considering variation of parameters such as value of common grounding, balance load and unbalance load.

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Analysis of Surge behavior on Branch Line in the Underground Distribution Systems (지중배전계통에서의 분기선로의 서지특성 해석)

  • Lee, Jang-Geun;Lee, Jong-Beom;Lee, Jae-Bong
    • Proceedings of the KIEE Conference
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    • pp.157-158
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    • 2006
  • This paper describes the overvoltage of branch line in underground distribution systems when the direct lightning surge strikes on conductor of overhead line. Distribution systems are very complex because that includes so many branch lines, transformers, switches and so on. Therefor model systems consist of overhead distribution lines, underground cable include branch lines, lightning source and switches. Those are established by EMTP/ATPDraw. Simulation analyzes surge behavior on branch lines considering various conditions in underground distribution systems. Simulation results shoe overvoltage with location in various cases.

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Bacterial Regrowth in Water Distribution Systems and Its Relationship to the Water Quality: Case Study of Two Distribution Systems in Korea

  • Yoon, Tae-Ho;Lee, Yoon-Jin
    • Journal of Microbiology and Biotechnology
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    • v.14 no.2
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    • pp.262-267
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    • 2004
  • This study was done to observe the occurrence of heterotrophic bacteria in terms of free chlorine residuals in two different water distribution systems, which belongs to both K and Y water treatment plant of S city in Korea. The data analyzed in the distribution systems show that the free chlorine residuals decreased from 0.10 to 0.56 mg/l for K, and 0.51 to 0.78 mg/l for Y. The decay of free chlorine is clearly higher in both March and August than in January. The HPC in the distribution systems are ranged from 0 to 40 cfu/ml for K, 0 to 270 cfu/ml for Y, on $R_2$A medium. In particular, its level is relatively high at the consumer's ground storage tanks, taps, and the point-of-end area of Y. The predominant genera that were studied in the distribution systems were Acinetobacter, Sphingomonas (branch of Pseudomonas), Micrococcus, Bacillus, Staphylococcus. The diversity of heterotrophic bacteria increases in the end-point area. Most of them are either encapsulated cells or of Gram-positve cocci. In conclusion, the point-of-end area in distribution systems shows the longer flow distance from the water treatment plants, along with a greater diversity and a higher level of heterotrophic bacteria, due to the significant decay of free chlorine residuals.