• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.19-21
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• 2003

In this paper, we studied on life-decision of underground cable of live-lines state. As all equipments have been wear, underground cables decided design-life on the whole 30 years because underground cable have been occurred aging as time goes. CV cable has been become about 30 years after installation in the South Korea, is come to a important point of time with estimation about life. Study target cable is 22 kV CV cables in this point of view and installation cable is about 10 years before and behind. Measurement method used dc leakage method of live-lines state that applied voltage of 50V in neutral point and data is analyzing result that is measured during 5 years. In this result, insulation resistance could confirm that change according to season and cause is effect of humidity, seasons and load current. Also, according as data is gone aging, insulation resistance by Weibull distribution could confirm functionally its decrease. As a result, the aging speed of cable that water tree is gone could confirm fastness very. Numerical analysis result, cable that water tree is not gone could confirm that life of cable that has passed 10 years remains about $10{\sim}20$ years.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.4
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• pp.345-350
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• 2001

Normal zone propagaton(NZP) properties were investigated on Bi-223/Ag tapes and prototype HTS cable. NZP experiments in tape were conducted in temperatures from 45K to 77K in zero field. Prototype HTS cable was molded using epoxy and the experiments were carried out under adiabatic condition in LN$_2$. NZP velocities in tapes with tow conditions of DC and AC currents were almost same at each temperature. NZP velocity in prototype HTS cable was 1.9-2.4 cm/sec in LN$_2$. Numerical analysis was carried out by a one-dimensional equation of heat balance. The simulation results of NZP velocity in Bi-2223/Ag tapes were similar to the experimental results.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1202-1203
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• 2015

This paper describes the development of HVDC ${\pm}500kV$ polypropylene laminated paper (PPLP) mass-impregnated (MI) type cable system for HVDC transmission lines. As you know, mass-impregnated type cable generally has only insulating layer with the Kraft paper impregnated with a high-viscosity insulating compound. But polypropylene laminated paper is made of a layer of extruded polypropylene (PP) film sandwiched between two layers of Kraft paper. Thanks to PP film and its combination with Kraft paper, PPLP has higher AC, Impulse (Imp.) and DC breakdown (BD) strengths as well as lower dielectric loss than conventional Kraft paper insulation. In addition, Kraft MI cable has a limitation for the maximum conductor temperature as $55^{\circ}C$ But this PPLP MI cable has higher maximum conductor temperature than that of Kraft MI cable due to advantage of oil drainage characteristics. It is the most economic type of cable for HVDC transmission. Also HVDC ${\pm}500kV$ PPLP MI cable system was developed including land joints and outdoor-terminations. In order to prove the mechanical and electrical performances, the type test was carried out according to CIGRE recommendations. A full scale cable system has been tested successfully. And additional load cycle and polarity reversal tests on the cable system showed a higher performance compared with a similar mass impregnated paper cable.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1688-1691
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• 1997

In this work, we have developed the off-line diagnostic system for power cable insulation using DC voltage decay method to diagnose the insulation degradation of underground power cables. Measurement errors of diagnostic system are less than 1% for $1T{\Omega}$ internal resistor. We have also developed measurement and diagnostic programs for win95 which is suitable for the database construction and the management of data. We could conclude that it is possible to apply this system to the multi-grounded underground cable systems.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.37-40
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• 1996

Cable-In-Conduit Conductor(CICC) is widely accepted as an advanced superconductor configuration for large scale applications such as tokamak fusion reactors, MAGLEV (MAGnetic LEVitation), and SMES (Superconducting Magnetic Energy Storage). The stability of CICC cooled with supercritical helium can be very high if it is operated below a certain limiting current. This limiting current can be determined by Stekly type heat balance equation. The stability characteristic of CICC for AC operation is more complicated than that of DC because there are additional instability sources which are associated with local flux change. Ramp-rate limitation is a phenomenon discovered during US-DPC (United States-Demonstration Poloidal Coil) program, which showed apparent quench current degradation associated with high dB/dt. This paper describes recent experimental investigation results on the ramp-rate limitation and discusses current imbalance, induced current, current redistribution due to local quench of the strand in the cable.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.455-457
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• 2007

The objective of this study is development of a installed working robot for a troy cable with mobile and tension system. In this paper, an approach to designing controllers for dynamic hybrid Tension/Mobile control of a installed robot for a troy wire cable is presented. Mobile control system of robot is designed based on equation of dc motor and motion for moving robot and tension control system is designed based on equation of ac servomotor for generating torque and dynamic equation of a wire cable. The control parameters is determined by simulation in independence operation of two system.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.367-368
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• 2015

최근에 인도와 유럽을 중심으로 기존의 AC 송전계통 중 일부를 DC 송전계통으로 대체하는 하이브리드형 송전방식에 대한 연구가 진행중이다. 따라서 본 연구는 기존에 연구되고 있는 하이브리드형 가공송전계통을 기반으로 지중송전계통을 포함한 하이브리드형 혼합송전계통이 향후 머지않아 국내에서 계획 및 건설될 것을 대비한 초기 연구로서 진행하였다. 본 논문의 관점은 하이브리드 혼합송전계통 중 지중송전계통구간에서 DC 선로가 AC선로로부터 얼마나 고조파 전압 및 전류 측면에서 영향을 받는가를 평가하고, 이를 근거로 DC 케이블의 배열을 선정하고자 한다. 또한 DC 케이블 배열 선정을 위해 가능성이 있는 여러 개의 CASE별로 구분하고, 가장 타당한다고 평가되는 배열을 제안하고자한다. 본 연구에서 계통 모델링 및 해석은 EMTP를 이용하였다.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.302-309
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• 2017

The ageing of XLPE cable insulation will lead to the accelerating accumulation of space charge, which will greatly affect the safe operation of the HVDC cable. In order to investigate the influence of different ageing modes on the space charge distribution of the HVDC cable, thermal stressed, electrical stressed and electro-thermal stressed endurance tests were carried out on the XLPE peelings. The tested XLPE peelings were obtained from 160kV HVDC cable insulation. The endurance tests were carried at thermal stress of 363K, electrical stress of 20kV/mm DC and a combination of both. The Pulsed Electro-Acoustic (PEA) method was used to measure the space charge distribution of the samples. The influences of ageing on the trap energy distribution were analyzed based on the isothermal relaxation theory and the decay characteristics of the space charge. The results showed that thermal ageing would help to improve the crystalline morphologies of the XLPE at the early stage. The total amount of space charge decreased compared to the ones before thermal ageing. The long term of electrical stress would result in the cleavage of polymer molecule chains which would intensify the accumulation of space charge and increase the density and depth of electron traps. With a combination of electrical and thermal stress, the injection and migration of space charge were more significant. Besides, the depth and density of electron traps increased rapidly with the increase of endurance time.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2315-2326
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• 2016

This paper discusses the elimination of DC voltage deviation and the enhancement of load current sharing accuracy in multi-terminal high voltage direct current (MT-HVDC) systems. In order to minimize the power line losses in different parallel network topologies and to insure the stable operation of systems, a decentralized control method based on a modified droop control is presented in this paper. Averaging the DC output voltage and averaging the output current of two neighboring converters are employed to reduce the congestion of the communication network in a control system, and the decentralized control method is implemented. By minimizing the power loss of the cable, the optimal load current sharing proportion is derived in order to achieve rational current sharing among different converters. The validity of the proposed method using a low bandwidth communication (LBC) network for different topologies is verified. The influence of the parameters of the power cable on the control system stability is analyzed in detail. Finally, transient response simulations and experiments are performed to demonstrate the feasibility of the proposed control strategy for a MT-HVDC system.

• KIPE Magazine
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• v.6 no.4
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• pp.21-26
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• 2001

HVDC Light는 300MW에 이르는 전력을 가지고 있는 아불 성형된 DC Cable과 Voltage Source 컨버터에 기반을 둔 가장 최근의 HVDC 기술이다. HVDC Light 컨버터는 IGBT(Insulated Gate bi-polar Transistor)와 유효전력과 무효전력 사이의 고속 컨트롤을 위한 PWM(펄스 폭 변조)의 기능을 가지고 있다. HVDC Light 케이블은 압출 성형된 폴리머의 절연을 가진 케이블이며 직류 전압을 위해 특별히 개조되었다. 전력 범위 내에서 HVDC Light 컨버터와 케이블은 지중 또는 해저 송전 등에서도 송전전력을 위해 훌륭하게 조합될 수 있었다. 본 원고는 실제의 케이스로부터 얻은 경험지식으로, HVDC Light 기술의 조합을 사용해 해결된 문제점을 소개하고, HVDC Light의 장점을 설명하였다.