• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.138-146
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• 2010

DC railway power supply system generally uses the running rails as negative-polarity return conductor for traction load current, and the induced rail potential and stay current cause serious problems to any electrified matter in the underground and also safety problems to human body. This paper presents a new algorithm for the analysis of the rail potential and the stray current in DC railway power system operated under independent/parallel power feeding mode. The effect of load current fluctuation during train operation is also calculated by using TPS(Train Performance Simulation) program to analysis the variation of the railway potential and stray current along railway track. Simulation program is developed based on the proposed algorithm and case studies are provided.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1248-1250
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• 2001

전기철도에서의 급전시스템은 레일을 귀선으로 사용하는 단상급전시스템을 사용하고 있다. 이에 따라 레일로부터 대지로의 누설에 의해 상당한 누설전류가 대지로 흐르게 된다. 대지로 흐르는 이 누설전류는 전자유도에 의해 선로 주변에 설치된 통신 케이블 또는 장치에 영향을 주게 된다. 더욱이 전기차의 견인시스템은 견인전동기를 제어하는데 있어서 스위칭 소자의 개폐에 의한 고조파 전류를 발생하고 있어 대지누설전류에 고조파 전류가 포함되어 흐른다. 본 연구에서는 전기철도 급전시스템에서 통신유도원인 대지누설전류에 따른 고려되어야 할 급전시스템 설계 파라미터를 시뮬레이션을 통하여 검증하였으며, 이 결과가 향후 급전시스템 설계시 기본적인 지침이 되어야 할 것이다.

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.290-292
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• 2002

전기철도 급전계통은 차량 또한 이동 부하이고, 비정상적인 전기적 특성이 나타날 수 있으므로, 전기적으로 정확한 해석을 할 필요가 있다. 본 연구는 PSCAD/EMTDC 과도해석 프로그램을 이용하여 직류 전기 철도 시스템을 모델링 함으로써 전기철도 급전계통의 정확한 특성을 연구하는 것이다. 한전 계통으로부터 전력을 급전 받아 전기철도차량 부하에 공급되는 급전계통을 실제와 가깝게 모델링 함으로써 정상상태 해석과 사고 시 과도특성 분석 및 계통에의 영향 해석을 목적으로 한다. 프로그램 특성상 각각의 소자를 모델링 한 후 4단자망 이론에 근거, 각 소자를 결합하여 전체 계통을 구성한다. 각각의 소자는 전차선로, 정류기 및 제어기를 포함한 차량부 (전동기, 제어소자), 정류 변전소 등으로 구성된다. 이 논문에서는 급전계통의 정상상태 및 고장전류를 분석함으로서 제안된 모델을 검증한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.160-168
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• 2010

This paper presents the analysis of the current as stray current and supplied current of the substation, on the DC railway power system. In DC railway power supply system, the running rails are usually used as the return conductor(negative-polarity) for traction load current. This condition mainly focuses on economic considerations, since it does not require the installation of an additional return conductor. But, problems of low resistance between the running rails for the return conductor and earth allows a significant part of the return load current to leak into the earth. This current is normally called to as leakage or stary current. This stary currents creates serious problems for any electrified matter in the underground. Therefore, reduction of stray current of the DC railway power supply system is also of direct benefit to the operational and safety aspects of the DC railway systems. In this paper, deal with the analysis of the current distribution on the DC railway power system applied the common grounding system, using SPLIT of CDEGS program.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.152-158
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• 2010

Generally, the AC electrified railway systems have the power quality problems that are induced from the harmonic currents and the reactive power. This paper presents a single-phase hybrid active filter adopting a SRF(synchronous-reference-frame) control for improving power quality in the AC electrified railway systems. The single-phase hybrid active filter can compensate the harmonic currents and the reactive power through the proposed SRF control algorithm. The proposed control algorithm can extract the third and fifth harmonics through the MSRF(multiple-synchronous-reference-frames) which is used to apply the three-phase systems. Therefore, the hybrid active filter can compensates only the high-frequency harmonic currents whereas the passive filter compensates the low-frequency harmonic currents. Also, the proposed SRF control algorithm can compensate the reactive power by the closed-loop control. The Validity and the effectiveness of the proposed SRF control method for the hybrid active filter are illustrated through the simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.220-229
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• 2004

The AC railway system is quite differing from the general electric power system because it is single- phase and intermittently heavy loads. Thus, inevitably power quality problems are occurred in the AC railway system, i.e. voltage regulation voltage sags, voltage imbalance, and harmonic distortion. Recently, the power quality of the AC railway system becoming a hot issue because it is affect the control and safety of high-speed traction. In addition it is also affect the power quality of the electric power system. In this paper, single-phase Unified Power Quality Conditioner(UPQS) for the AC railway system is proposed to compensate the voltage sags and harmonic distortion. The configurations and control schemes of the proposed single-phase UPQC are presented. The effectiveness of the proposed single-phase UPQC application is verified by the PSCAD/EMTDC simulation works. It can be shown that the application of UPQC in the AC railway system is very useful to compensate the voltage sags and harmonic distortion from the results of related simulation works.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.30-33
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• 2001

도시철도 DC 급전시스템은 부하전류가 사고전류보다 클 수 이는 특징을 가지고 이다. 이러한 이유로 DC 급전시스템에서는 di/dt를 측정하여 사고전류를 부하전류로부터 구분하고 있다. 이것은 사고전류의 di/dt와 부하전류의 di/dt는 서로 다른 상이한 특성을 보이고 있기 때문이다. 본문에서는 DC도시철도급전시스템에서 흔히 사용되는 di/dt 계전기와 이의 설정을 위한 사고전류의 분석 및 설정방법에 대해 알아본다.

• Journal of the Korean Society for Railway
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• v.12 no.5
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• pp.694-699
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• 2009

This paper presents a synchronous-reference-frame-based control of single-phase UPQC(Unified Power Quality Conditioner) to improve power quality in ac electrified railway systems. The proposed synchronous-reference-frame-based UPQC can compensate the voltage distortion, the voltage sag, the harmonic currents, and the reactive power instantaneously. The simulation results show that the UPQC can compensate the harmonic supply voltages, the voltage sag, the harmonic load currents, and the reactive power in electrified railway systems. Validity and effectiveness of the proposed UPQC control method based on the synchronous-reference-frame is illustrated through the simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.42-51
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• 2007

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion my also occur to AC electrical railroad system. These problems affect not only power system stability, but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, andthen, it is analyzed voltage drop for AC electrical railroad system both with single-phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.694-698
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• 2005

The operation speed improvement of the train in electric railway must pursue continuously and need the investigation of whole railway system whole. The high-speed of the train is related to not only vehicle technique but also the infrastructure, signal system, operation technique, the trolley line and catenary, economical efficiency. Specially, in case of electric railway, we have to consider a technical investigation which is current collection efficiency improvement, voltage drop countermeasure, equipment capacity, track force, signal system. In this paper, we presents the technical investigation of AT feeder system in order to achieve high speed train in exist real railroad. We proved this approach which will use the whole domestic lines in the future.