• 전기학회논문지
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• 제60권9호
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• pp.1788-1794
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• 2011

The mold transformer is a complex and critical component of DC substations in Metro system. In this paper, a cost effective and intelligent condition monitoring system for mold transformers in DC substations was developed. This paper also provides an overview of the management program using PD (partial discharge) data on mold transformers. Prior to application of the proposed system to Metro DC substations, experiments were performed at the metro line substation located in Seoul and presented case studies for the use of the intelligent condition monitoring system for mold transformer in DC substations. The experiment results indicated that the developing system can be need in helping mange the risk of unexpected failure of mold type transformers.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1997-2004
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• 2011

The $2{\times}25kv$ AT electric power feeding method in the A.C. electric train adopts the one-phase power feeding method as the standard due to a voltage phase difference, and the distance between the two neighboring substations is 50km due to voltage drop. The one-phase power feeding method makes the system operation feasible, while making it unfavorable for power supply. Moreover, railroad involves large-capacity single-phase load, and if it is expected to continue to rise, it is necessary to research on measures to stabilize the supply of power to railroad cars with the existing facilities. In this study, a parallel power feeding method between neighboring substations is proposed to stabilize the supply of electric power to electric railroad cars under the 2*25kv AT power feeding method and the loop current induced by voltage phase difference between the two neighboring substations during parallel power feeding is investigated.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권4호
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• pp.172-177
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• 2005

The testing and evaluating shunting rates of operating substations have become difficult recently due to various factors including increased fault current, limited area of urban substations and construction of substations in mountain location. In this paper, we have analysed the computation and measurement method of shunting currents that be applied grounding system maintenance of power substations. Also, simple and detailed test methods using 70Hz current injection are explained. A computer program is developed for a study on the shunting properties such as grounding impedance and shunting rates of grounding current, and the simulation results are compared with the measurement data to prove validity and effectiveness of the program and measurement method under commercial operation of a GIS type model substation respectively.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.836-845
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• 2007

In DC 1500V electric traction substations, diode rectifiers are commonly used to supply stable DC power with electric train sets. However, it operates in the first quadrant of the voltage-current plane and thus needs regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul line 2 and Kwangju line 1. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power for four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy.

• 조명전기설비학회논문지
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• 제27권5호
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• pp.54-60
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• 2013

There is increasing demand for practical groundings for small-area substations because of the recent revision of Korea's Electrotechnical Regulations, which necessitates the method of evaluating their safety. This paper proposes a practical mesh grounding system for 22.9kV substations and studies how to evaluate its safety. The proposed grounding system is proved to obey the safety criteria of ANSI/IEEE Std. 80 via ANSI/IEEE Std. 80 method and computer simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.905-907
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• 1996

Current design standard of substation grounding systems is primarily concerned with conventional outdoor substations. But in case of 154kV substations in the nation, almost all are indoor-type GIS substations. So there became to be something not proper for application of present design standard to indoor-type substations. In this paper, as a preliminary stage of drawing-up of the grounding system design standard which concerned with in-door-type substions, issues of current design standard are mentioned and directions of improvement are also presented.

• 전기학회논문지
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• 제57권11호
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• pp.1962-1969
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• 2008

According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint is increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation of the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated core noise reduction techniques to develope a low noise transformer. The techniques to reduce core noise of the transformer are application of high permeability grain oriented silicon sheets, decrease of magnetic flux density of core, application of 6step-lap core stacking method, improvement of core binding method(binding addition, band fixing) and application of rubber damper in oder to reduce transmission of core vibration, etc.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.438-439
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• 2011

Substations in Korea are classified into an outdoor steel structure type, an outdoor GIS(Gas Insulated Switchgear) type, an indoor GIS type, an underground GIS type, and a complex GIS type. Before 1970, substations were built in outdoor steel structure types only. In 1980, an 154kV indoor GIS type substation was built for the first time in Pusan. And the first 345kV indoor GIS type substation, the first 765kV full GIS substation were built in 1984 and in 2002 each. In 1998, 154kV indoor type substations were standardized into regular type and urban type which applied steel frames to structures. In 2002, this was re-standardized into five different types in detail. In 2007, hub substations which had high capacity were built in the region of industrial zone and heavy load areas. And 154kV compact substation was developed and standardized by compacting an indoor GIS type substation in 2009. This paper would present a series of substation type transition and application standards for substation types and facility scales.

• 전기학회논문지P
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• 제59권1호
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• pp.35-39
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• 2010

The IT project for power plants initiated domestically in 2005 necessitates the power equipment facility and the controllers for those to be sufficiently adaptable for automation system for power substations. This implies that the power plants using power equipments must be developed to satisfy the IEC61850 standards. The IEC61850 communication standards that all power equipment and facility and controllers installed in automation system for power substations must follow has had its Parts 3 and Part 4 established as international standard in January 2002 and Part 10 in May 2005, the last to become international standard. Hence all separate parts of the original IEC61850 standard came to be established as international standards. As a consequence, after 2005, in most power substations around the world the IEC61850 standard is being applied and the prominent makers are geared towards manufacturing products to the IEC61850 standard. The IEC61850 is being recognized as an essential standard that must be applied to not only power substations but for automation of power systems and communication systems. In this research, the Gateway device that connects current SCADA system and IEC61580 based system has been domesticated with Korea‘s own technology and extensive testing was carried out in order to obtain confidence in its performance.

• 전기학회논문지
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• 제57권10호
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• pp.1759-1766
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• 2008

According to the increase of power demand and expansion of downtown, it is necessary to install transformers additionally in operating substations and construct substations in residential area. But the public complaint has been increased due to the transformer noise of the substation. KEPCO has used a vibration preventing pad, various soundproof walls and an encloser to transformers in outdoor substations, and a soundproof door, shutter and wind-path soundproof equipment in indoor substations to block the sound propagation from the transformers. But these noise reduction methods are not satisfied. It should be considered to reduce transformer noise itself. In this paper, we investigated tank noise reduction techniques to develope a low noise transformer. According to the mode analysis of transformer tank, we found out characteristics and locations of noise on the tank, and it's nature vibration was also analysed. On the basis of these analysis, reinforcement equipment was installed around transformer tank, and ellipse shape tank was changed to round shape tank. The effect of noise reduction was evaluated using noise generation source.