• 전력전자학회논문지
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• 제20권6호
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.505-511
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• 2008

when electric traction system used DC 1500V runs on decline of rail road track and slows down, dc voltage goes beyond regular voltage. In this case extra power is forcibly wasted by resister because rectifier of substation and electric train including power converter and so on are out of order. This paper described a DC electric railway system, which can generate the excessive DC power form DC bus line to AC source in substation for traction system. The purpose of this study was the development of the regenerative inverter system which suppress extra DC-line voltage and regenerate the energy instead of using a resister. That is Developed regenerative inverter system returns the regenerative energy from the DC line voltage to the utility. In addition, the inverter can be compensate the harmonics caused by the power conversion devices used in the DC traction system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.804-808
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• 2007

when electric traction system used DC 1500V runs on decline of rail road track and slows down, Dc voltage goes beyond regular voltage. In this case extra power is forcibly wasted by resister because rectifier of substation and electric train including power converter and so on are out of order. This paper described a DC electric railway system, which can generate the excessive DC power form DC bus line to AC source in substation for traction system. The proposed regeneration inverter system for DC traction can be used as both an inverter and an active power filter(APF). As a regeneration inverter mode, it can recycle regenerative energy caused by decelerating tractions and as an active power filter mode, it can compensate for harmonic distortion produced by the rectifier substation. In addition, electric traction system products harmonic current and voltage distortion and reactive power because power converter is used so regeneration inverter normally runs such as active power filter(APF) for improving power quality. From the viewpoint of both power capacity and switching losses, the system is designed on the basis of three phase PWM inverters and composed of parallel inverters, output transformers, and an LCL filter.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1303-1308
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• 2004

This paper proposes a reduction method for the mis-operation analysis of the DC High Speed Circuit Breaker(HSCB) in electric railway substation system. The analysis method is based on present condition of operation which is a method for accuracy level up. There is reason to operation of HSCB that it is mis-operation of fault detection relay(50F), operation of ground fault relay(64P), and trouble of electric car. A countermeasure is relay resetting through field test, induction of GTOCB(Gate Turn Off Thyristor Circuit Breaker), HSVCB(High Speed Vacuum Circuit Breaker), coordination with electric car. The results presented in the paper can be used as a reference for maintenance free in electric railway substation system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.676-681
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• 2005

The regenerative braked cars are being introduced in DC electric railway for energy saving. There has been a recent tendency for DC traction substation with regenerative inverter to increase in number. This is strongly related to the desire for effective utilization of electric power regenerated by DC electric cars and to the aim ensuring stable operation of regenerative braking system. The regenerative inverters DC power feed back from a generative car into AC power at a substation and supplies it to distribution lines. This paper suggest the result of characteristic analysis and capacity simulation. economical analysis in the regenerative inverter system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1597-1598
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• 2015

Regenerative power utilization is one of the most interesting issue in electric railway systems. Generally, technologies to utilize regenerative power from railway vehicles are railway substation with regenerative inverter, on-station energy storage systems, and on-board energy storage systems. In this paper, the electric power loss for those technologies is calculated and compared using DC electric railway system analysis algorithm.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.52-59
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• 2014

Operator training simulator, within a training environment designed to understand the principles and behavior of the railway system with respect to operator's entries and predefined scenario, can provide a very strong benefit in facilitating operators' handling undesired operations. This simulator consists of computer system and applications, and the purpose of applications is to generate the power and voltage and analyze the AC substation and DC railway, respectively. This paper describes a novel approach to the new techniques for AC/DC hybrid simulation for the operator training simulator in the railway system. We first propose the structure the database of railway system. Then, topology processing and power flow using a linked-list method based on the proposed database, full or decoupled newton-rapshon methods are presented. Finally, the interface between the analysis for AC substation using a newton-rapshon method and the analysis for DC railway system using a time-interval power flow method is described. We have verified and tested the developed algorithm through the extensive testing for the proposed test system. To demonstrate the validity of the developed algorithm, comparative simulations between the proposed algorithm and PSS/E for the test system were conducted.

• 한국철도학회논문집
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• 제19권3호
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• pp.314-323
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• 2016

직류 전철변전소의 가선전압은 전동차들의 회생제동 및 역행가속패턴에 따라 급격히 상승 또는 하강하는 특성을 갖는다. 가선전압 순시 변동폭을 최소로 유지함으로써, 전철변전소와 전동차들의 에너지 효율을 개선시키기 위한 다양한 연구들이 이루어지고 있다. 본 논문은 직류전철 변전소의 가선전압의 급격한 변동특성을 모델링하고 선형인공 신경망 알고리즘을 이용한 가선전압 회로모델의 파라메터 추정 방법을 제안하며, 최소자승법을 이용한 추정방법과의 비교를 통해 이 방법의 타당성을 입증한다. 가선전압 및 피더전류들의 누적 측정값을 사용하여 일괄처리 최소자승법으로 RC 병렬회로의 파라메터들을 추정한 결과를 제시하며, 실시간 가선전압 및 피더전류 측정값을 이용하여 오차역 전파방식으로 학습되는 선형인공신경망 기법 추정 결과를 분석한다.

• 전기학회논문지
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• 제60권4호
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• pp.892-898
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• 2011

In DC electric railways, while an electric rail car is driving, a part of the working current returned to the substation through rails leaks into the ground. Such a stray current causes railway facilities and metal objects to corrode electrolytically. Therefore, change of stray current needs to be monitored constantly. But so far in domestic, the research on stray current measuring techniques and system adaption are insufficient. To estimate stray current, this paper addresses a method of monitoring the return current that is returned into the negative pole of the substation in real time.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.478-485
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• 2017

Urban DC railways have played an important role in urban transportation, and railway operation and energy management have been emphasized to be important to achieve maximum efficiency from existing infrastructure. Fast, accurate DC railway power flow analysis is required to operate a DC railway efficiently, and this paper proposes a novel methodology to analyze the DC railway power network by implementing the participation factor (PF). The PF concept consists of a correlation between the vehicle and the substation, as explained using zones based on the position of the vehicles running on the route. Then, the DC railway powerflow is calculated using the PF concept. Finally, the usability of the proposed method was validated via case studies with actual railway operation data, and we discuss some of the advantages of the suggested methodology.