• Title, Summary, Keyword: Underground transmission systems

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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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A Study on the Sequence Impedance Modeling of Underground Transmission Systems (지중송전선로의 대칭분 임피던스 모델링에 관한 연구)

  • Hwang, Young-Rok;Kim, Kyung-Chul
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.6
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    • pp.60-67
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    • 2014
  • Power system fault analysis is commonly based on well-known symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. The majority of fault in transmission lines is unbalanced fault, such as line-to-ground faults, so that both positive and zero sequence impedance is required for fault analysis. When unbalanced fault occurs, zero sequence current flows through earth and ground wires in overhead transmission systems and through cable sheaths and earth in underground transmission systems. Since zero sequence current distribution between cable sheath and earth is dependent on both sheath bondings and grounding configurations, care must be taken to calculate zero sequence impedance of underground cable transmission lines. In this paper, EMTP-based sequence impedance calculation method was described and applied to 345kV cable transmission systems. Calculation results showed that detailed circuit analysis is desirable to avoid possible errors of sequence impedance calculation resulted from various configuration of cable sheath bonding and grounding in underground cable transmission systems.

A Study on the Fault Discrimination and Location Algorithm in Underground Transmission Systems Using Wavelet Transform and Fuzzy Inference (지중송전계통에서 Wavelet 변환과 퍼지추론을 이용한 고장종류판별 및 고장점 추정에 관한 연구)

  • Park, Jae-Hong;Lee, Jong-Beom
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.55 no.3
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    • pp.116-122
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    • 2006
  • The underground transmission lines is continuously expanded in power systems. Therefore the fault of underground transmission lines are increased every year because of the complication of systems. However the studies dealing with fault location in the case of the underground transmission lines are rarely reported except for few papers using traveling wave method and calculating underground cable impedance. This paper describes the algorithm using fuzzy system and travelling wave method in the underground transmission line. Fuzzy inference is used for fault discrimination. To organize fuzzy algorithm, it is important to select target data reflecting various underground transmission line transient states. These data are made of voltage and average of RMS value on zero sequence current within one cycle after fault occurrence. Travelling wave based on wavelet transform is used for fault location. In this paper, a variety of underground transmission line transient states are simulated by EMTP/ATPDraw and Matlab. The input which is used to fault location algorithm are Detail 1(D1) coefficients of differential current. D1 coefficients are obtained by wavelet transform. As a result of applying the fuzzy inference and travelling wave based on wavelet transform, fault discrimination is correctly distinguished within 1/2 cycle after fault occurrence and fault location is comparatively correct.

Analysis of Sheath Induction Voltage for 154kV OF Underground Cable (154kV OF 지중케이블의 씨스 유도전압 해석)

  • Lee, H.G.;Kim, D.K.;Bae, J.H.;Ha, T.H.;Choi, S.B.;Jeong, S.H.
    • Proceedings of the KIEE Conference
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    • pp.156-158
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    • 2000
  • As we are industrialized lately, power capacity is increased in the city urban areas. So the application of underground transmission line is largely expended. In this paper, we analysis the induction voltage on the sheath of 1,200[$mm^2$] OF underground cable being used 154kV underground transmission line. If the current on the cable conductor is 300[A], circulation current is induced the maximum 100[A] on the cable sheath.

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Magnetic Field Analysis in Accordance with Line Configuration Type in Underground Transmission Systems (지중송전계통에서 선로의 구성방식에 따른 자계 해석)

  • Lee, Jae-Myeong;Lee, Jong-Beom
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.12
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    • pp.1673-1678
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    • 2015
  • This paper describes magnetic field on power cable in underground transmission systems. Based on specification which is being used in domestic power utility, magnetic field was analyzed in accordance with line arrangement, line burial depth and phase spacing. Magnetic field magnitude and its trend were understood in each circuit type such as double circuits, triple circuits and quadruple circuits of underground transmission systems. In addition, magnetic field was analyzed according to phase arrangement changing in each circuit. Finally, the proper phase arrangement configuration type was suggested by the evaluation of analysis result. Magnetic field was calculated by using Biot-Savart's law. According to the evaluated magnetic fields based on phase layout configuration in each circuit, it figured out that each of magnetic fields was different. As a result, this paper proposes a proper phase layout configuration for generating minimum magnetic field. It is evaluated that the phase layout configuration in each circuit proposed in this paper can be used at actual underground transmission systems.

Analysis of the Earth Resistance for the Tower Footing of T/L (송전선로 철탑기초의 접지저항 해석)

  • Lee, H.G.;Ha, T.H.;Bae, J.H.;Kim, D.K.
    • Proceedings of the KIEE Conference
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    • pp.344-346
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    • 2001
  • The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. During a fault on any of the transmission lines, energization of the earth by supporting structures near the fault can result in large voltages appearing locally between the earth and the steel wall of any nearby pipeline. This paper presents the outline of the tower footings for the transmission lines having been used in KEPCO and analyzes the earth resistance for operation method of the tower footing, that is contact presence for the anchor and reinforcing rob of the tower and foundation presence of the underground wiring.

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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.

Analysis of Switching Surge in Overhead Transmission Line with Underground Cable Line (가공 및 케이블로 구성된 선로의 개폐서지 해석)

  • Kang, Y.W.;Shim, E.B.;Joo, B.S.;Kim, M.D.
    • Proceedings of the KIEE Conference
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    • pp.1938-1940
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    • 1996
  • As transmission systems has been complicated and various, cases of transmission systems which is made up with underground cable line only or overhead transmission line with underground cable line have been increased. When transmission lines with different types of cable, it is more likely to be vulnerable to the surges. This paper analyzed these surge in 154kV transmission line by means of EMTP (Electro Magnetic Transient program).

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A Study on Overvoltage Reduction Method of Single Point Bonded Section on Combined Transmission Lines (혼합송전선로 편단접지 구간 과전압 저감 방안에 관한 연구)

  • Jung, Chae-Kyun;Kang, Ji-Won;Park, Hung-Sok;Kim, Jin
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.10
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    • pp.1881-1887
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    • 2009
  • This paper discusses the effects of ECC (Earth Continuity Conductor) for reducing the level of induced sheath overvoltages at the single point bonded section of combined transmission lines which are mixed underground power cable with overhead line in one T/L. In previous papers, the characteristics of ECC on only underground power cable systems were sufficiently analyzed. However, the result of only underground power cable systems are totally different from that of combined transmission lines because ECC is commonly grounded with overhead grounding wire at mesh of cable head. Therefore, in this paper, the installation effects of ECC have been variously analyzed considering the three kinds of fault positions, cable formation of duct and trefoil, spacing between phase conductor and ECC, and the change of overhead transmission line section length on 154kV combined transmission line. Finally, simulation results show that ECC can effectively reduce the induced sheath voltage.

Fault Location in Combined Transmission Systems Using Wavelet Transform (웨이브렛 변환을 이용한 혼합송전계통에서의 Fault Location)

  • Jung, Chae-Kyun;Hong, Dong-Suk;Lee, Jong-Beom
    • Proceedings of the KIEE Conference
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    • pp.226-229
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    • 2001
  • The combined transmission lines with the underground power cables are continuously expanded in power systems. So the fault of combined transmission line is increased every year as the complication of underground transmission line. In this paper. traveling wave theory and DWT wavelet transform are used for fast and accurate detection of fault location at the combined transmission line. Traveling wave travels to each bus like surge and repeats reflection and transmission till transient signal is completely disappeared. When fault is occurred on overhead and underground tine, the fault location detecting algorithm was performed with using continuous peak value time-delay of traveling wave reflected from A bus.

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