• Title, Summary, Keyword: Transfer stability

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Assessment of Total Transfer Capability Using IPLAN: An Application of UPFC for Total Transfer Capability Enhancement

  • Lee Byung Ha;Kim Jung-Hoon;Kwak No-Hong;Lee Woon-Hee
    • KIEE International Transactions on Power Engineering
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    • v.5A no.3
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    • pp.244-251
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    • 2005
  • Power transfer capability has been recently highlighted as a key issue in many utilities. It is determined by the thermal stability, dynamic stability and voltage stability limits of generation and transmission systems. In particular, voltage stability affects power transfer capability to a great extent in many power systems. This paper presents a tool for determining total transfer capability from a static voltage stability viewpoint using IPLAN, which is a high level language used with the PSS/E program. The tool was developed so as to analyze static voltage stability and to determine the total transfer capability between different areas from a static voltage stability viewpoint by tracing stationary behaviors of power systems. A unified power flow controller (UPFC) is applied for enhancing total transfer capability between different areas from the viewpoint of static voltage stability. Evaluation of the total transfer capability of a practical KEPCO power system is performed from the point of view of static voltage stability, and the effect of enhancing the total transfer capability by UPFC is analyzed.

A Study on Location of STATCOM for Improvement of Total Transfer Capability and Analysis of Total Transfer Capability Considering Transient Stability (전체송전용량 향상을 위한 STATCOM 설비의 적용 위치 선정 및 과도안정도를 고려한 전체송전용량 분석)

  • Lee, Byung-Ha;Baek, Jung-Myoung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.4
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    • pp.17-24
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    • 2010
  • The power transfer capability has been recently highlighted as a key issue in many utilities with the power system more stressed and heavy loaded. The total transfer capability in the KEPCO power system is determined mainly by the voltage stability limit and many approaches for enhancement of the total transfer capability has been consistently performed. In this paper, a new transfer capability index to locate the STATCOM(Static Synchronous Compensator) effectively for enhancing the total transfer capability from a static voltage stability viewpoint is presented and it is applied to a small scale power system of IEEE 39-bus test system in order to show the effects of this index. In addition, the effect of transient stability as well as voltage stability to the total transfer capability when loads are increased is analyzed using this small scale power system.

Load Transfer Characteristics on Drilled Shafts by Hole Stability Fluids (공벽유지용 유체에 따른 대구경 현장타설말뚝의 하중전이특성)

  • Lim, Dae-Sung;Park, Seong-Wan;Park, Jung-Hwan;Oy, Se-Hun
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1100-1105
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    • 2008
  • In most drilled shafts construction sites, it is common, depending on the site condition, to use either water or slurry as fluids for maintaining stability of the holes, however, there are yet no design manuals by hole stability fluids. In this paper, in order to evaluate load transfer characteristics of the drilled shafts by hole stability fluids, two test piles are constructed over the soft ground of the lower Busan Bay based on the Bi-directional Pile Load Test. The test results showed that no ultimate states has found under the condition of applied loads with fresh water and slurry as hole fluids for drilled shafts. Then, the load transfer behavior were estimated with the data measured in fields and the effect of hole stability fluids were compared. All these results are presented in the paper.

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Effect of S on Arc Stability of MAG Welding (MAG용접의 Arc안정성에 미치는 S의 영향)

  • 안영호;이종봉;엄동석
    • Journal of Welding and Joining
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    • v.17 no.1
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    • pp.55-61
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    • 1999
  • The effect of S content in welding wires on the arc stability was investigated, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing S content, average arcing time and average short circuit time were decreased. Therefore, droplet transfer frequency was increased, due to the reduction of arcing time and peak current at the moment of arc-reiginition was decreased, due to the decrease of short circuit time. In the region of spray transfer, the fluctuation degree of arc current and arc voltage became more stable, with increasing S content.

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Effect of Si on Arc Stability of MAG Welding (MAG용접의 Arc안정성에 미치는 Si의 영향)

  • 안영호;이종봉;엄동석
    • Journal of Welding and Joining
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    • v.16 no.6
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    • pp.52-58
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    • 1998
  • The effect of Si content in welding wires on th arc stability was investigate, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing Si content, average arcing time and average short circuit time were increased. Therefore, droplet transfer frequency was decreased, due to the increase of arcing time and peak current at the moment of arc-reiginition was increased, due to the increase of short circuit time. In the region of spray transfer, the fluctuations of arc current and arc voltage was the most stable in wire with Si content of about 00.60 wt.%.

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Effects of Wire speed Fluctuation on Arc Stability in GMA Welding (GMAW에서 와이어 송급속도의 변동이 아크안정성에 미치는 영향에 관한 연구)

  • 신현욱;최용범;성원호;장희석
    • Journal of Welding and Joining
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    • v.13 no.4
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    • pp.85-102
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    • 1995
  • Weld quality of GMA welding processes is closely related to arc stability. Although many researches on arc stability have been performed, real-time estimation of arc stability has not been attempted. For instance, Mita proposed a off-line statistical method in which short circuiting and arcing time, and voltage and current wave forms were sampled to assess arc stability. But this method is not suitable to assess arc stability for GMA welder which employ inverter power source due to its controlled current and voltage wave forms. In this paper, the relationship between are stability and wire feed rate fluctuation is analyzed to propose new criterion for inverter power source. When arc voltage and arc current and arcing time are analyzed, we can assess arc stability only for short circuit transfer mode. When wire feed rate is analyzed, we can estimate arc stability udner the condition of spray transfer mode as well. Hence, the wire feed rate is chosen for monitoring process variable to cover possible metal transfer modes in GMAW. Through this research, it has been identified that arc stability in GMA welding processes is closely related to wire fed rate. When inverter power source is used, conventional statistical method of estimating arc stability, such as Mita index, is no longer valid due to its controlled voltage and current wave forms. Arc stability has been also examined in phase plane diagram.

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Calculation of Active Power Transfer Capability using Repeated Power Flow Program

  • Ham, Jung-Pil;Kim, Jung-Hoon;Lee, Byung-Ha;Won, Jong-Ryul
    • KIEE International Transactions on Power Engineering
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    • v.12A no.1
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    • pp.15-19
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    • 2002
  • The power transfer capability is determined by the thermal, dynamic stability and voltage limits of the generation and transmission systems. The voltage stability depends on the reactive power limit and it affects the power transfer capability to a great extent. Then, in most load flow analysis, the reactive power limit is assumed as fixed, relatively different from the actual case. This paper proposes a method for determining the power transfer capability from a static voltage stability point of view using the IPLAN which is a high level language used with PSS/E program. The f-V curve for determining the power transfer capability is determined using Repeated Power Flow method. It Is assumed that the loads are constant and the generation powers change according to the merit order. The maximum reactive power limits are considered as varying similarly with the actual case and the effects of the varied maximum reactive power limits to the maximum power transfer capability are analyzed using a 5-bus power system and a 19-bus practical power system.

A Study on the Application of Frontal Transfer Matrix Method to the Beam and the Torsional System (보 및 비틀림계에 대한 Frontal 전달매트릭스법의 적용성에 관한 연구)

  • 김영식
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.2
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    • pp.46-52
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    • 1986
  • The transfer matrix method has been extensively used to analyze the vibration problem. The final stage in this method is to find out solutions which make the frequency determinant zero. However, the frequency determinant includes the exponential terms and it causes instability to calculation and increases error. Recently the frontal transfer matrix method was suggested by Okada to heighten stability and effectivity in calculation. This paper applied the frontal transfer method to both the beam and torsional system, and confirmed stability and effectivity in comparsion with the transfer matrix method and the Holzer method.

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Contingency Ranking for Determining Total Transfer Capability from Voltage Stability Point of View (전체송전용량 결정을 위한 전압안정도 측면에서의 상정사고 순위 매김)

  • Lee, Byung-Ha;Baek, Jung-Myoung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.2
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    • pp.148-154
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    • 2008
  • The power transfer capability has been recently highlighted as a key issue in many utilities. The total transfer capability in the KEPCO power system is determined mainly by the voltage stability limit and an enormous number of contingencies should be analyzed to determine the total transfer capability. In this paper, a new ranking index for determining the total transfer capability from voltage stability point of view is presented. This index is applied to the practical system of KEPCO and the effects of ranking the contingencies are analyzed by use of PSS/E package and a developed IPLAN program.

Effects of HTS Cable Applied to the Voltage Stability Limited Power System (전압 안정도 제약계통에 대한 고온초전도 케이블 적용효과)

  • Lee, Geun-Joon;Hwang, Si-Dol
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.18 no.5
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    • pp.169-173
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    • 2004
  • This paper presents the basic application idea of superconductor cable for voltage stability limited power system. In bulk power system, the transfer capability of transmission line is often limited by the voltage stability, and superconductor cable could be one of the countermeasure to enhance heat transfer limit as well as voltage stability limit. Steady state voltage stability approach by P-V curve is used to calculate the maximum transfer capability of initial system and superconductor applied system. IEEE-14 bus system is used to demonstrate its applicability.