• Title/Summary/Keyword: power distribution line

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Transformer Winding Modeling based on Multi-Conductor Transmission Line Model for Partial Discharge Study

  • Hosseini, Seyed Mohammad Hassan;Baravati, Peyman Rezaei
    • Journal of Electrical Engineering and Technology
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    • v.9 no.1
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    • pp.154-161
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    • 2014
  • To study and locate partial discharge(PD) and analyze the transient state of power transformer, there is a need for a high frequency model of transformer winding and calculation of its parameters. Due to the high frequency nature of partial discharge phenomenon, there is a need for an accurate model for this frequency range. To attain this goal, a Multi-Conductor Transmission Line (MTL) model is used in this paper for modeling this transformer winding. In order that the MTL model can properly simulate the transformer behavior within a frequency range it is required that its parameters be accurately calculated. In this paper, all the basic parameters of this model are calculated by the use of Finite Element Method (FEM) for a 20kV winding of a distribution transformer. The comparison of the results obtained from this model with the obtained shape of the waves by the application of PD pulse to the winding in laboratory environment shows the validity and accuracy of this model.

Insulation coordination of 765 KV double circuit transmission line (765 KV 2 회선(回線) 송전선(送電線) 절연협조(絶緣協助))

  • Kim, Jeong-Boo;Min, Suk-Won;Lee, Dong-Il
    • Proceedings of the KIEE Conference
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    • 1988.07a
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    • pp.774-777
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    • 1988
  • This paper covers the insulation coordination of 765 KV transmission line in Korea Electric Power Corporation. The design for the lightning, switching surge, and contamination was conducted to increase the reliability of 765 KV line. The authors have used the result of a limited Westinghouse ANACOM swiching surge study of the Korea Electric Corporation's 765 KV Expansion plan. The study investigated the switching surge overvoltage distribution and maximum switching overvoltage when relosing 765 KV lines. They used the technical data of the suspension insulator for the contamination design, which was available from a foreign insulator manufacture. From this paper, the authors find out that the contamination design dominates to determine the number of insulator and the SOV design dominates the air clearance in the tower. Afterwards the authors will confirm this design by Demonstration Test with Korea Electro-technology Research Institute.

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Fault Location Estimation Algorithm in the Railway High Voltage Distribution Lines Using Flow Technique (반복계산법을 이용한 철도고압배전계통의 고장점표정 알고리즘)

  • Park, Kye-In;Chang, Sang-Hoon;Choi, Chang-Kyu
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.2
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    • pp.71-79
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    • 2008
  • High voltage distribution lines in the electric railway system placed according track with communication lines and signal equipments. Case of the over head lines is occurrence the many fault because lightning, rainstorm, damage from the sea wind and so on. According this fault caused protection device to wrong operation. One line ground fault that occurs most frequently in railway high voltage distribution lines and sort of faults is line short, three line ground breaking of a wire, and so on. For this reason we need precise maintenance for prevent of the faults. The most important is early detection and fast restoration in time of fault for a safety transit. In order to develop an advanced fault location device for 22.9[kV] distribution power network in electric railway system this paper deals with new fault locating algorithm using flow technique which enable to determine the location of the fault accurately. To demonstrate its superiorities, the case studies with the algorithm and the fault analysis using PSCAD/EMTDC (Power System Computer Aided Design/Electro Magnetic Transients DC Analysis Program) were carried out with the models of direct-grounded 22.9[kV] distribution network which is supposed to be the grounding method for electric railway system in Korea.

A Study on Fault Characteristics of DFIG in Distribution Systems Based on the PSCAD/EMTDC (PSCAD/EMTDC를 이용한 풍력발전의 배전계통 사고특성에 관한 연구)

  • Son, Joon-Ho;Kim, Byung-Ki;Jeon, Jin-Taek;Rho, Dae-Seok
    • Journal of the Korea Convergence Society
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    • v.2 no.2
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    • pp.47-56
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    • 2011
  • Korea Ministry of Knowledge Economy has estimated that wind power (WP) will be occupied 37% in 2020 and 42% in 2030 of the new energy sources, and also green energies such as photovoltaic (PV) and WP are expected to be interconnected with the distribution system because of Renewable Portfolio Standard (RPS) starting from 2012. However, when a large scale wind power plant (over 3[MW]) is connected to the traditional distribution system, protective devices (mainly OCR and OCGR of re-closer) will be occurred mal-function problems due to changed fault currents it be caused by Wye-grounded/Delta winding of interconnection transformer and %impedance of WP's turbine. Therefore, when Double-Fed Induction Generator (DFIG) of typical WP's Generator is connected into distribution system, this paper deals with analysis three-phase short, line to line short and a single line ground faults current by using the symmetrical components of fault analysis and PSCAD/EMTDC modeling.

Performance of 2-Carrier DS system and its MODEM designed for Power Line Transmission (전력선 통신을 위한 2-반송파 DS방식의 특성과 MODEM의 구현)

  • 김인태;이무영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.19 no.3
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    • pp.582-590
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    • 1994
  • This paper introduce a highly verstile and simple data transmission system designed for commercial power distribution lines. The system operates on the DSSS principle but utilizes two independent carrier frequencies each represents polarity of DS MODEM outiputs. At the receiving terminal, outputs of two envelope detectors are directly applied to separate DS correlators before the two components are compared. The recovered signals which represents data and line noise are then compared at comparator. With the noise power greatly rudused at the correlator, the error rate of the data observed at comparator desplays great improvement comparing to the conventional FSK-DS system in which the detector output are compared before the correlator stage. Despite its simplest structure, the prototype MODEM transmitts 2400 bps with the error rate 10 , about 10dB improved compared to conventional FSK system.

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The solution for preventing the expansion of cable joint caused by methane($CH_4$) gas to Water proof type of power cable (도체 수밀형 전력케이블의 가교잔사 가스에 의한 직선접속재 부풀음 현상 방지 대책)

  • Kim, Jong-Won;Lee, Ki-Soo;Paek, Heum-Soo;Choi, Bong-Nam;Park, Hee-Cheol
    • Proceedings of the KIEE Conference
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    • 2000.07c
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    • pp.2020-2022
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    • 2000
  • The cross-linked polyethylene(herein after XLPE) insulated power cable emit the methane($CH_4$)gas in the course of chemical cross-linking process. The general stranded conductor easily discharge this methane gas through the gap of each stranded wires. But the special stranded conductor that filled with semi-conducting rubber compound to prevent water penetration which is applied to water proof type of cable(22.9kV CN/CV-W), disturb the methane gas emission. The pre-mold type cable joint shall be expanded gradually by emit of gas left in XLPE insulation. For example, sometimes the corona problem outbreak on a new power distribution line, resulted from the gap between the sleeve and semi-conductive layer of cable joint. If above mentioned problem especially happened on the way of operating. We have to shut down the line and try to discharge the methane gas in cable joint. In this point, we would like to explain the mechanism of methane gas & cable joint and our test result briefly. At last, we are pleased to introduce the solution for preventing reoccurrence of this problem.

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Tele-Diagnosis of Electric Power Apparatus Using Analyzation of Temperature Distribution (온도분포분석을 이용한 수전설비 원격진단)

  • Lim, Yong-Bae;Chun, Jong-Chul;Jung, Sung-Chun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.212-215
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    • 2003
  • This paper presents constitution of a moderate price thermography system for on-line measurement. All objects with some temperature above absolute zero radiate in the infrared. The intensities and spectra of the infrared radiated from some object depend on the conditions and temperature distributions on the surface of the objects, and the temperature distributions differ from each others with different undersurface structures. Consequently, infrared radiation is useful for diagnosis of the conditions on the surface and undersurface of electric power apparatus. But the present, because engineers directly measure the temperatures of apparatuses in off-line, the measured data do not always have the information of the past. The proposed system is able to analyze not only the information of the past but the trend of deterioration, and the system is able to compensate for the distortion of surface temperature as to weather conditions. The thermal image histogram is equalized to upgrade observability, and a pan-tilter is adopted to control of direction for any target point.

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The methodology on the application of EEG as a diagonostic measures in Korean Traditional Medicine (뇌파의 한의학적 진단 지표로의 활용 방안에 대한 연구초안)

  • Seo, Young-Hyo;Kim, Gyeong-Cheol;Kim, Bo-Kyung
    • Journal of Oriental Neuropsychiatry
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    • v.18 no.1
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    • pp.37-61
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    • 2007
  • Objective : By examining EEG status in Korean Traditional Medicine (KTM) from the viewpoint of 'form-qi theory(形氣論)', We wish to prepare for the fundamentals of applicability of KTM diagnoses to EEG. In addition, through reinterpretation of existing Western Medicine reports from the viewpoint of KTM, We tried to find out interrelationship between them. Method : In this paper, a methodology applicable to KTM diagnoses of EEG is presented from the EEG features in waveform characteristics, personalized diversity, and cognitive activity reflection. Results : Frequency bands are assigned to corresponding one of the eight trigrams in terms of yin/yang balance, which is analogous with EEG spectrum analysis mostly used in EEG quantification. The amplitude ratio of each EEG for each frequency band gives meaningful index numbers which can be used in EEG data interpretation, and every index number is named after the sixty four hexagrams. These approaches are adopted through both '4-band classification system and '6-band classification system', and applied to pre-existing reported EEG data obtained from normal adults. These analyses show that changes and distribution pattern in the index numbers are observed as a whole on both left-right line and front-back line connecting EEG measurement cephalic electrodes. And differences in distribution pattern of three index numbers deduced from '6-band classification system' are discussed according to constitution. Conclusion : The index numbers introduced here, which are the spectral power ratio for each EEG, are based on KTM yin/yang balance. These index numbers vary according to cephalic location, so its application in terms of traditional meridian theory is strongly expected. The index number distribution also shows different patterns according to constitution.

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DEVELOPMENT OF A TWO-DIMENSIONAL THERMOHYDRAULIC HOT POOL MODEL AND ITS EFFECTS ON REACTIVITY FEEDBACK DURING A UTOP IN LIQUID METAL REACTORS

  • Lee, Yong-Bum;Jeong, Hae-Yong;Cho, Chung-Ho;Kwon, Young-Min;Ha, Kwi-Seok;Chang, Won-Pyo;Suk, Soo-Dong;Hahn, Do-Hee
    • Nuclear Engineering and Technology
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    • v.41 no.8
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    • pp.1053-1064
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    • 2009
  • The existence of a large sodium pool in the KALIMER, a pool-type LMR developed by the Korea Atomic Energy Research Institute, plays an important role in reactor safety and operability because it determines the grace time for operators to cope with an abnormal event and to terminate a transient before reactor enters into an accident condition. A two-dimensional hot pool model has been developed and implemented in the SSC-K code, and has been successfully applied for the assessment of safety issues in the conceptual design of KALIMER and for the analysis of anticipated system transients. The other important models of the SSC-K code include a three-dimensional core thermal-hydraulic model, a reactivity model, a passive decay heat removal system model, and an intermediate heat transport system and steam generation system model. The capability of the developed two-dimensional hot pool model was evaluated with a comparison of the temperature distribution calculated with the CFX code. The predicted hot pool coolant temperature distributions obtained with the two-dimensional hot pool model agreed well with those predicted with the CFX code. Variations in the temperature distribution of the hot pool affect the reactivity feedback due to an expansion of the control rod drive line (CRDL) immersed in the pool. The existing CRDL reactivity model of the SSC-K code has been modified based on the detailed hot pool temperature distribution obtained with the two-dimensional pool model. An analysis of an unprotected transient over power with the modified reactivity model showed an improved negative reactivity feedback effect.

Characteristics of loci on Line-to-Earth Voltage according to Earth Fault in Earthing System for Ships (선박의 접지 시스템에서 지락 고장에 따른 대지 전압 변동 특성)

  • Kim, Jong-Phil;Ryu, Ki-Tak;Lee, Yun-Hyung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.487-495
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    • 2021
  • The voltages mainly used in ships are 450 [V], 6.6 [kV], and 11 [kV], and an earthed system is applied to ensure the stability of the power distribution system. In general, low-voltage ships using 450 [V] apply an unearthed system, while high-voltage ships using 6.6 [kV] or 11 [kV] use a high-resistance earthed system. When an earth fault occurs in a ship's power distribution system, the voltage of the healthy phase increases to the line-to-line voltage or higher, which causes an excessive impact on the insulation of the cable. Thus, analyzing this behavior is very important. In this paper, we investigate the characteristics of the line-to-earth voltage variation according to earth faults and a recognition procedure of a faulty phase using the symmetrical coordinate method for a high-resistance earthed system and unearthed system. A mathematical model of the line-to-earth voltage was derived through the symmetric coordinate method, and the ship voltage for simulations was selected as 6.6 [kV] and 450 [V]. A MATLAB simulation proved that this method can determine the highest increase of the line-to-earth voltage, which leads by 120° on the faulty phase, and it accurately judges the faulty phase in both earthed systems.