• Proceedings of the KSR Conference
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• 2000.11a
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• pp.712-719
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• 2000

This paper presents a new algorithm to analyze a train voltages of multi-trains in auto-transformer-fed AC railway systems, using electrical equivalent change. The train current will be divided into circulation and return currents, and these current values are the same. By evaluating each current independently, the result will be more precise. The train current flows through the all auto-transformer corresponding to track impedance. In analyzing the railway system, the algorithm is based on the K.C.L, K.V.L, superposition and circuit separation method. Multi-train's voltages are determined by calculating the catenary voltage at each train's position and adding up these train's voltage drop. Case studies use a field operational data, show that tile proposed method is easily applied.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.108-115
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• 2000

This paper presents the new simulation algorithms using network methods to analysis the steady-state train voltage distribution characteristics in ac auto-transformer fed railroads. In general, the supply system of railroads is composed of non-symmetrical and unbalance transmission line. Therefore, the general method using simplified old algorithms have the self-contradictory errors because the supply line of train railroads is completely unbalanced. In this paper, the simulation results of new developed algorithms is compared with those of EMTP to confirm the effectiveness.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.360-367
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• 1999

An inverter-driven induction motor is used as the traction motor for a high speed drive system that required safety, reliabillity, performance, compact size owing to the space and weight alloted for attaching to train, etc. particularly it is possible to happen the saturation effects of flux density at constant voltage-frequency region and then increase very higher than the at lowed capacity of no-load current and temperature in any case. therefore the optimum design of core, optimum voltage-frequency ratio, adoption of high grade magnetic core have been developed and researched for preventing these problems. this paper show the saturation effects of traction rotor by measuring the induced voltage of search coil at stator teeth and presents optimum voltage-frequency ratio as well as optimum core design through the comparison with efficiency, power factor, load current and no-load current for korea high speed train.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.65-70
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• 2010

AC traction power supply system has adopted autotransformer (AT) feeding method. This system has an advantage as long feeding distance. However, the countermeasure for voltage drop should be considered, because load capacity grows larger and headway grows shorter in recent electric railway system. This paper proposes the improved system configuration to enhance voltage drop in ac railway system without additional power electronic device. That is to increase turn ratio between contact wire and rail of AT. By modifying turn ratio of AT at SSP or SP, collecting voltage on train will be enhanced.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.258-262
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• 2004

In this paper, the hazard factors on voltage rising effect between the rail and the earth were reviewed in subway system of AC traction line according to moving condition and location of the train. Site measuring of voltage rising between conductor part of train and station floor was performed to ascertain the risk level on the passenger. Plans for preventing hazard of rail-voltage rising and electrical shock on the passengers at platform were proposed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.8
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• pp.490-495
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• 2015

This paper was proposed the theoretical research and optimal design 3,000 V IGBT for using electrical automotive, high speed train and first power conversion. To obtaining 3,000 V breakdown voltage, the design parameters was showed $160{\Omega}{\cdot}cm$ resistivity and $430{\mu}m$ drift length. And to maintain 5 V threshold voltage, we obtained $6.5{\times}10^{13}cm^{-2}$ p-base dose. We confirmed $24{\mu}m$ cell pitch for maintain optimal on state voltage drop and thermal characteristics. This 3,000 V IGBT was replaced to thyristor devices using first power conversion and high speed train, presently.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.754-760
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• 2011

In the DC traction system, a large load current of electric railcar leads to a voltage drop when a vehicle starts, and the regenerative power generated by brake system increases the catenary voltage. To minimize the voltage fluctuation during the train operation and make use of the regenerative power, several types of energy storage systems are being studied. The energy storage system that is being recently introduced consists of the supercapacitors for energy storage and the bi-direction DC/DC converter for charge/discharge control. The efficiency of the energy storage system depends on the train operation pattern. In this paper, the operation efficiency of the energy storage system was quantitatively analyzed via simulation study taking consideration of the train operation patterns. The simulation was conducted changing the headway of trains with the energy storage system that uses the bi-direction DC/DC converter and supercapacitor. The simulation results showed that the operation efficiency of the energy storage system increases as the headway increase.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1163_1164
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• 2009

AC AT feeding method consists return circuits of electric train inserting in parallel between trolly line and feeding line and connecting neutral line to rail and FPW. Due to increasing train number, electric load at feeding system are increasing and collecting voltage of train are going down. To increase electric load and collecting voltage between trolly line and rail, the usefulness of new autotransformer are considered which variation of short impedance and change of line voltage is simulated with modified winding ratio of autotransformer from 1:1 to variable tab.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.655-659
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• 2005

The environment. of electric railway has, included both fast and slow load variation, which may occur in the office or maintenance factory or running electric train. This paper investigated flicker indices according to voltage fluctuations on three different situations; The base office in new subway in the daytime and night time, inside of electric train running in conventional subway. And also the variations of harmonic frequencies(2nd, 3rd, 5th) with rime were measured at the same time. Flicker index is a good tool for evaluating the voltage fluctuation quantitatively and show some relationship with even harmonic frequencies produced by the voltage fluctuation when the electric train is running on the railway.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.81-89
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• 2004

AC electric railroad system receives its power from 3-phase transmission system. Since trainloads are moving continuously, the voltages for the single load fluctuate in the train garage, and moreover, the fluctuating voltages generate high-order harmonics. This means the difficulty in maintaining power quality in the power system. Therefore, in this paper, the adequacy of SVC application is investigated for the train garage in KNR(Korean National Railroad). Voltage drop, voltage regulation, and unbalanced voltages are assessed in the train garage for the condition of power system both with svc and without SVC. In this paper, PSCAD/EMTDC is used for the above assessment items, and the results are compared with ones which was already designed in the field in practice for the train garage. As a result, the train garage using SVC improves power quality.