• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.191-196
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• 2010

The electricity distribution system in Korea is adopting a multi-grounding system. Protection of this distribution system against lightning is performed by installing overhead ground wires over the high voltage wires, and connecting the overhead ground wires to the ground every 200 m. The ground resistance in this system is limited not to exceed $50\Omega$ and overhead ground wire and neutral wire are multiple parallel lines. Although overhead ground wire and neutral wire are installed in different locations on the same pole, this circuit configuration has duplicated functions of providing a return path for unbalanced currents and protecting the distribution system against induced lightning. Therefore, the purpose of this study is to analyze the induced lightning shielding effect according to the neutral wire installation structure of a 22.9kV distribution line in order to present a new 22.9kV distribution line structure model and characteristics. This study calculated induced lightning voltage by performing numerical analysis when an overhead ground wire is present in the multi-grounding type 22.9kV distribution line structure, and calculated the induced lightning shielding effect based on this calculated induced lightning voltage. In addition, this study proposed and analyzed an improved distribution line model allowing the use of both overhead wire and neutral wire to be installed in the current distribution lines. The result of MATLAB simulation using the conditions applied by Yokoyama showed almost no difference between the induced lightning voltage developed in the current line and that developed in the proposed line. This signifies that shielding the induced lightning voltage through overhead wire makes no difference between current and proposed distribution line structures. That is, this study found that the ground resistance of the overhead wire had an effect on the induced lightning voltage, and that the induced lightning shielding effect of overhead wire is small.

• 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.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1394-1400
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• 2014

The current flowing through the overhead transmission lines causes induced voltage on the communication lines, which can be prevented by calculating the induced voltage at the planning stage for overhead transmission line installment through an agreement between the communication and electric power companies. The procedures to calculate the induced voltages, however, are complicated due to the variety of parameters and tower types of the overhead transmission lines. The difficulty necessitates the development of a simulator to measure the induced voltage on the communication lines. This paper presents two simulators developed for this purpose; one using the Data Base (DB) index method and the other using the Graphic User Interface (GUI) method. The simulators described in this paper have been implemented by the EMTP (Electromagnetic Transient Program).

• 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 Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.11
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• pp.2035-2040
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• 2008

The electrical discharge of high voltage direct current(HVDC) overhead transmission line generate audible noise, radio noise, electric field, ion current and induced voltage on the ground. These items are major factors to design environmentally friendly configuration of DC transmission line. Therefore, HVDC transmission lines must be designed to keep all these corona effects within acceptable levels. Several techniques have been used to assess interference caused by ions on HVDC overhead transmission line. In this study, to assess the ion characteristic of DC line, the ion current density and induced voltage caused by ion flow were measured by plate electrodes manufactured from a metal flat board and charged bodies, respectively. The charged body has two types of cylinder and cylindrical plate. From the results of calibration experiments, the sensitivity of flat electrode and charged body can be obtained. At present, the developed system is used to investigate the ion generation characteristics of Kochang DC ${\pm}500kV$ test line.

• Journal of the Korean Society for Railway
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• v.19 no.3
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• pp.314-323
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• 2016

Overhead line voltage of DC railway traction substations has rising or falling characteristics depending on the acceleration and regenerative braking of the subway train loads. The suppression of this irregular fluctuation of the line voltage gives rise to improved energy efficiency of both the railway substation and the trains. This paper presents parameter estimation schemes using the RC circuit model for an overhead line voltage at a 1500V DC electric railway traction substation. A linear artificial neural network with a back-propagation learning algorithm was trained using the measurement data for an overhead line voltage and four feeder currents. The least square estimation method was configured to implement batch processing of these measurement data. These estimation results have been presented and performance analysis has been achieved through raw data simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1136-1146
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• 2005

In this paper, the radiative electric field intensity due to the communication signal and conductive noise is calculated in overhead medium voltage power lines for power line communication. The input impedance is calculated by means of 2 port equivalent model of medium voltage power line network and basic transmission line theory. And then, currents is calculated by calculated input impedance and finally, the emissive electric field is calculated. The input impedance appears like a standing wave form with a fixed cycle because high reflection at the input terminal due to the characteristic impedance of medium voltage power line is very large. A calculated current and radiative electric field also appears like this form. From the measurement results, the measured results are very similar to the calculated results.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.93-99
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• 2000

Using the EMTP(Electro Magnetic Transient Program) for the analysis of lightning direct voltage on the railway system, the shielding effects of overhead grounding wire on the railway were studied quantitatively. Installation of overhead ground wire and gap-type arrester such as s-horn Provides a 6.6㎸ HV distribution line with good protection effects. Even severe lightning induced voltage were create, 6.6㎸ HV lines can be withstand.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.9
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• pp.1638-1643
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• 2010

HVDC is better economic method than HVAC in case of long distance transmission and it is possible to interconnect transmission lines regardless of difference of power frequency. The electrical environment problems of HVDC overhead transmission line are electric field, charged voltage, ion current and so on. For biopolar HVDC lines, most of the ions are directed toward the opposite polarity conductor, but a significant fraction is also directed toward the ground. These problems are major factor to design configuration of HVDC overhead transmission line. Therefore, It is necessary to test an environmental characteristics of HVDC overhead transmission line. In this paper, to assess the ion characteristic of HVDC transmission line, continuous measurements have been done on the biopolar single circuit line with ACSR 480mm2-6 bundle conductors of Gochang HVDC Test line. And then the ion characteristics were analyzed.

• 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.