• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1641-1643
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• 1998

In recent the maximum voltage of overhead power transmission lines in Korea was upgraded to 765kV. In general a overhead ground wire is installed for protecting overhead power transmission lines from lightning. For the 765kV line, Composite Overhead Ground Wire with Optic Fiber (OPGW) is applied as a overhead ground wire and have a function of the communication line between substations. In this paper, the construction and properties of OPGW, and its installation methods are discribed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.7
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• pp.566-569
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• 2018

A power line coupler that can apply high-frequency power to a railway overhead line structure was analyzed. It is difficult to supply auxiliary power to an overhead line in a high-voltage environment, and doing so requires a long-distance transfer. A method is proposed that utilizes the resonance on the Rogowski coil, which does not use a magnetic core. A simple overhead line structure was fabricated that consisted of a contact wire, messenger wire, and dropper. Couplers of various sizes were fabricated and deployed on the messenger wire, and the transfer characteristics of the two couplers were compared at a distance. As a result of applying the matching circuit to the coupler, the transmission efficiency was 53% at a distance of 2.5 m. The proposed method shows that it is possible to apply the auxiliary power by using the existing conductor in a special structure, such as the overhead line.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.534-539
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• 2015

The DC overhead line voltage of an electric railway substation swings depending on the accelerating and regenerative-braking energy of trains, and it deteriorates the energy quality of the electric facility in the DC railway substation and restricts the powering and braking performance of subway trains. Recently, an energy storage system or a regenerative inverter has been introduced into railway traction substations to diminish both the variance of the overhead line voltage and the peak power consumption. In this study, the variance of the overhead line voltage in a DC railway substation is modelled by RC parallel circuits in each feeder, and the RC parameters are estimated using the recursive least mean square (RLMS) scheme. The forgetting factor values for the RLMS are selected using simulated annealing optimization, and the modelling scheme of the overhead line voltage variation is evaluated through raw data measured in a downtown railway substation.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.204-205
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• 2006

This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.191-206
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• 2004

The present study investigated the hypothesis that a extremely low frequency magnetic field partially suppresses the synthesis of melatonin in a group of 28 primary schoolchildren living nearby and 60 primary schoolchildren aged 12 years living far away from overhead transmission power lines from December 2003 to April 2004 in Seoul, Korea. The mean personal exposure levels of the primary schoolchildren living nearby overhead transmission power line were 0.37 ${\mu}$T, whereas the value for the primary schoolchildren living away from overhead transmission power line 0.05 mT. From simple analyses, the mean melatonin levels in the primary schoolchildren living nearby were lower than away from overhead transmission power line, but not statistically significant differences in the levels of the melatonin (p=0.2421), whereas the statistically significant differences in the levels of the melatonin related to the distance from residence to power line less and more than 100 m by cut-off point (p=0.0139). In multiple linear regression analyses, distance from residence to power line (p=0.0146) and dietary habit about burned meat (p=0.0170) proved to be significant risk factors in the mean nocturnal melatonin levels in the primary schoolchildren. In conclusion, these results demonstrate that urinary levels of nocturnal melatonin are not altered in primary schoolchildren exposed to extremely low frequency magnetic field(ELF-MF) at overhead transmission power line.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3052-3058
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• 2011

A high-speed train is the system that the electric power is supplied through the overhead contact line and drives motors. In this case that the de-wiring beteen the overhead contact line and the pantograph of a high-speed train, the occasion that smooth power supply is not accomplished occurs sometimes. If the de-wiring occurs, the arc discharge may damage the overhead contact line or the pantograph, and the falling-off in power quality may cause the damage and malfunctioning of motor block. This paper presents the methodology that the arc discharge by de-wring between overhead line and pantograph is discriminated through measuring the PT and CT in the vehicle, and measures the current collection characteristics for a high speed train.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.27-29
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• 2005

Overhead transmission line design supporting program using high spatial resolution satellite imagery has been developed recently by Korea Power Engineering Company, The developed program, ITSS(Interactive Tower Spotting System) is purposed to improve the application of satellite imagery with the route selection of overhead transmission line. It is composed of spotting the tower position and designing the tower type and height with DEM(Digital Elevation Model) overlaid with satellite Imagery. To review and confirm the function and work efficiency, ITSS was applied to the pilot project of overhead transmission line design.

• 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.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.3
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• pp.183-187
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• 2016

Recently, power demand has been increasing every year according to variation of electrical equipments and temperature rise in summer season. So, much more overhead line is being demanded to copy with increasing power demand and operate reliable power system. This paper analysis the characteristics of long span overhead transmission line using special high-tension wire in such as a safety factor, coefficient of elasticity, and the coefficient of linear expansion. Based on the analysis, we proposed the effectiveness of special high-tension wire having much more advantages with respect to height of steel tower and dip compared with conventional ACSR in long span overhead transmission line.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2345-2347
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• 2005

In this paper, impedance characteristics of overhead medium-voltage (MV) power lines is reported for power line communication (PLC) over an MV power line network. For analysis, a two-port equivalent network model of MV power lines is derived. By applying the transmission line theory, reflection behavior and impedance of power lines are investigated. For verification, impedance of power lines is measured at a test field for an MV PLC. The results show that impedance of MV power lines is between $200{\Omega}$ and $300{\Omega}$ and converges to a half of their characteristic impedance.