• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1108-1114
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• 2016

The cause of failure in the AT feeding system is divided into grounding, short-circuit of feeding circuit and internal faults of the railway substation. Since the fault current is very high, real-time current is detected and the failure must be immediately removed. In this paper, a new DC offset elimination filter that can remove component to decrease in the form of exponential function using low-pass filter was proposed in order to extract the fundamental wave from distorted fault current. In order to confirm the performance of the proposed filter method, AT feeder system was modelled by simulation tool and simulations were performed under various conditions such as fault location, fault resistance and fault voltage phase angle in case of trolley-rail short-circuit fault. When applying the proposed DC-offset removal method, it can be seen that the phase delay and gain error did not appear.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.166-168
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• 2008

DC feeding system is mainly floating but the rail potential and the leakage current are created because of long parallelism between rails and ground. Rail potential causes electric shock to human and leakage current causes electrolytic corrosion to nearby the buried metals. Therefore the design technologies to reduce, protect and monitor these effects are important recent DC feeding system. Rail potential and leakage current are analysed based on propagation theory that is utilized in order to simulate grounding system. New measurement procedure is proposed based on this analysis in order to more be accurate in result.

• 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.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.2
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• pp.77-86
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• 2005

The DC protection and control device for the feeding system of a Light Rail Transit(LRT) system is developed. For the development, the short circuit characteristics in the system are analyzed. As a result a protection algorithm for the DC fault selective relay (50F) is newly proposed, and principles of the DC fault selective relay, Line Test Device (LTD), DC Over Current Relay (DC OCR) are introduced From the development, the specifications and codes used to be unclear have become clarified and summarized. Moreover, the methods to examine the protective characteristics and Electromagnetic Compatibility (EMC) are established Finally, the performance and the effectiveness of the developed protective relay have been verified with the test based on IEC. For the reliability of the system, the relay has been installed and is being operated at the test track of the LRT system at Gyeong-San.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.514-520
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• 2010

This paper is about control algorithms that bi-direction DC-DC Converter using Super Capacitor and regenerative power from DC feeding system in train. In order to take advantage of regenerative energy efficient, charge and discharge level value of energy storage system serve as an important factor. Respect to output fluctuations of the substation and catenary voltage changing, we offers Charge-Discharge Auto Level Tuning Algorithms to improve system following of Energy Storage System.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.86-97
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• 2006

For the design of DC traction power supply system at new Light Rail Transit(LRT) construction, it is very important to determine system configuration, location and power capacity of substation. However, a LRT system consists of a number of subsystems such as train movement, power supply and traction drives, which inevitably contains many complexities and diversities. The objective of this paper is to clarify and systematize the design procedure and its assessment for the electrification system of a LRT line. This paper discusses in detail our approach to system design and its assessment. The whole DC-feeding network configuration, characteristics of a train, and design method of substation arrangements is thoroughly investigated for the design. As a result of the investigations, the design procedure is clarified and systematized and a computer program for the design and evaluation of the system is developed using the most suitable iterative method with nodal equation. To verify the proposed design and its assessment procedure, case studies for the DC traction power supply system of a planed Korean LRT line are performed.

• Journal of Power Electronics
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• v.9 no.1
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• pp.43-50
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• 2009

This paper deals with a novel solid state controller (NSSC) for an isolated asynchronous generator (IAG) feeding 3-phase 4-wire loads driven by constant power prime movers, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of the asynchronous generator. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 2-leg voltage source converters (CC- VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The neutral point of the load is created using aT-configuration of the transformers. The IAG system is modeled in MATLAB along with Simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of the isolated generating system consisting of NSSC and IAG driven by uncontrolled pico hydro turbine and feeding 3-phase 4-wire loads.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.161-166
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• 2009

DC feeding system is mainly floating but rail potential and leakage current are due to long parallelism between rails and ground, namely rail resistance and rail to ground conductance. Rail potential causes electric shock to human and rail leakage current causes electrolytic corrosion to nearby the buried metals. Therefore the design technologies to reduce, protect and monitor these effects are important in recent DC feeding system. Rail potential and leakage current are analysed based on propagation theory that is utilized. Monitoring and controlling rail leakage current is proposed in order to maintain rail resistance and rail to ground conductance.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.358-365
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• 2007

This paper deals with a novel solid state controller (NSSC) for parallel operated isolated asynchronous generators (IAG) feeding 3-phase 4-wire loads in constant power applications, such as uncontrolled pico hydro turbines. AC capacitor banks are used to meet the reactive power requirement of asynchronous generators. The proposed NSSC is realized using a set of IGBTs (Insulated gate bipolar junction transistors) based current controlled 4-leg voltage source converter (CC-VSC) and a DC chopper at its DC bus, which keeps the generated voltage and frequency constant in spite of changes in consumer loads. The complete system is modeled in MATLAB along with simulink and PSB (power system block set) toolboxes. The simulated results are presented to demonstrate the capability of isolated generating system consisting of NSSC and parallel operated asynchronous generators driven by uncontrolled pico hydro turbines and feeding 3-phase 4-wire loads.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1251-1253
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• 2001

This paper presents on capacity design of DC-fed-traction system. The system is introduced including a characteristics of train, feeding network configuration, and design method of substation arrangements. Optimal design procedures is described, and program for capacity computation of the system is presented using the nodal equation, K.C.L, K.V.L, Ohm's law and superposition theory. For the proof of the proposed algorithm, we accomplished the simulation of DC traction system for HA-Nam LRT. By considering whole component in DC traction system the conclusion will be much precise.