• Journal of Power Electronics
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• v.6 no.3
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• pp.214-225
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• 2006

The design and performance analysis of a reduced rating autotransformer based thirty-pulse AC-DC converter is carried out for feeding a vector controlled induction motor drive (VCIMD). The configuration of the proposed autotransformer consists of only two single phase transformers, with their windings connected in a T-shape, resulting in simplicity in design, manufacturing and in a reduction in magnetics rating. The design procedure of the autotransformer along with the newly designed interphase transformer is presented. The proposed configuration has flexibility in varying the transformer output voltage ratios as required. The design of the autotransformer can be modified for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The proposed thirty-pulse AC-DC converter is capable of suppressing less than $29^{th}$ harmonics in the supply current. The power factor is also improved to near unity in the wide operating range of the drive. A comparison of different power quality indices at AC mains and DC bus is demonstrated in a conventional 6-pulse AC-DC converter and the proposed AC-DC converter feeding a VCIMD. A laboratory prototype of the proposed autotransformer based 30-pulse AC-DC converter was developed with test results validating the proposed design and system.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.948-953
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• 2011

In AC railway feeding system, three phase received from the network is changed to two phase power sources with different phases. The main circuit breaker installed train is automatically open by track signal when the train passes the neutral section. In order to continuously supply power source to train, the changeover system was used in Japan. Therefore, the train is able to operate under powering condition when it was passing through the neutral section. We investigated the control method to reduce the inrush current flowing main transformer in train. To examine the inrush current and operate the static semiconductor switch such as thyristor, we manufactured the small scale the changeover system and carried out performance tests.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1659-1665
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• 2015

In general, AT(Auto-transformer) is used to improve voltage sag and inductive interference in power lines and communication lines in AC electrical railway feeding system. Especially, Korean AT feeding system has different composition compared to other countries like Japan or France, so that it has some special characteristics. However, relays imported from other countries have been used in Korea, and settings of these relays should be modified and reflect distinct characteristics of Korean AT feeding system. Therefore, study about fault analysis based on modeled AT feeding system is important. In this paper, we modeled a single track AT feeding system by using PSCAD and analyzed fault current flow in case of trolley-rail short circuit fault. Finally, we presented current magnitude of each branch expressed by boosting current of AT.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1426-1430
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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 electric load at feeding system, collecting voltage of train and end voltage are going down. So to increase 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 KIEE Conference
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• 2015.07a
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• pp.1617-1618
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• 2015

This paper analyzed catenary impedance characteristics of relays installed in substation and sectioning post to protect power feeding circuit in the extended power feeding conditions. For this, we modelled AT feeding system using PSCAD/EMTDC and calculated catenary impedance. The relay installed in substation calculated catenary impedance of the extended power feeding area adding catenary impedance of self protection zone. But, the relay installed in sectioning post calculated catenary impedance of the only protection area. Therefore, we confirmed that the more reliable protection way can be utilized using the relay installed in sectioning post.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1849-1854
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• 2010

Energy Storage System(ESS) is installed at feeding line of railway substation. ESS will absorb regenerative energy when train braking and also charge electric energy when feeding line is no load condition. Absorbed and charged energy will be supplied when train is accelerating condition. Due to ESS the energy variation will be minimized and this effect is estimated.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.1
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• pp.137-141
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• 2018

The voltage drop is important in electric railway for feeding a huge power of train on fixed feeding area. Nowadays it is tried to operate a high speed trains on conventional lines and there is problem on the voltage drop too. It is simulated on the conditions increased the turn ratio of trolley, installed autotransformer neutral line with variable taps. In result, it is compensated the voltage drop between ATs and better on last AT, not on the position of AT. And it is decreased a return current and neutral current of AT because of unbalance between trolley and feeder. It should be studied faster and more controllable the solid state switchs instead of the mechanical one in order to utilize this system.

• Journal of the Korean Society for Railway
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• v.14 no.5
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• pp.404-410
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• 2011

In AC feeding system, the fault location is calculated by using ratio of current absorbed in the neutral point of AT(Automatic Transformer) or by measuring reactance. In this way, however, an estimation error can be happened due to the many reasons. In addition, for measuring currents in the neutral point of AT, other measuring devices and communication equipments are additionally required. In order to solve the disadvantages, this paper suggests a novel technique using the distribution ratio of catenary current. The proposed technique uses existing protective relays and measures catenary current. With the measured data, we can calculate the distribution ratio of catenary current and determine fault location. Through the simulated results, we derived the correlation between current ratio and fault location. Using this technique, additional equipments and expenses can be reduced. Besides, fault location can be determined more correctly.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.2
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• pp.325-330
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• 2018

In this paper, we investigated the impedance method for searching fault detection point in case of an accident in the AC electric railway AT feeding system. For this purpose, simulation circuit modeling and prototype hardware are made based on the known numerical analysis. As a result of simulation modeling of the feeding system based on the numerical analysis of the impedance method confirmed that the modeling was properly implemented with an average error rate of 0.07%. Also, as a result of fault event by hardware simulator, it was confirmed that the breaker operation time is shortened and the fault current is decreased while the voltage is close to the supply voltage in the transient state as the point of the fault accident moves away from the substation(SS).