• Journal of Power Electronics
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• v.17 no.3
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• pp.788-797
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• 2017

The power quality of AC electric railways has become an issue worthy of more and more concern. Many active compensators based on power converters have been proposed, but with complex transformers or coupled branches. This paper presents a single-phase cascaded H-bridge multilevel active power filter (APF), which can directly connect to the 27.5-kV power supplies to deal with power quality problems. According to field measured data, the load characteristics are analyzed, and the system configuration and control system are designed based on the load characteristic analysis. Finally, simulation and experimental results verify the effectiveness of the proposed APF system, considering some problems such as the supply voltage fluctuations and transient inrush currents in AC electric railway systems.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.765-770
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• 2008

This paper presents the power control for the hybrid electric propulsion system. In this paper, the hybrid propulsion system consists cf the generator and battery as power supply system in ship. The hybrid control system is designed with energy saving algorithm for decreasing the power consumption of power supply system. This paper suggests the method to increase efficiency of hybrid electric propulsion system by developing battery charging system. The performance of power control system is analyzed with the experiment equipment for hybrid propulsion system, and the results showed a good property.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.132-137
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• 2005

In Korea, the protection systems against the instability of the nation's power system are insufficient in contrast with many other countries. In addition, there have just been studies carried out on detecting power system instability, while only a few studies pertaining to protection plans against instability exist. This paper focuses on systems to protect against the instability phenomena in the Korean power system. In this paper, we survey possible contingencies in the Korean power system and suggest outline and specs of the SPS (System Protection Scheme) against faults on the 765 kV line, based on simulations. It is concluded that event-based SPS for transient stability is appropriate for the Korean power system. In the simulations, the most severe contingency on the Korean power system is the fault on 765 kV transmission lines. If one of these lines is tripped by a fault, synchronism may be lost on the power plants near this line because of heavy power flow carried by them. In addition, undervoltage in the Metropolitan region is a serious problem in this case since this region receives about half its total power flow through these lines. In order to prevent a synchronism loss, some power plants have to be rejected according to the situations in the simulations.

• Journal of Power Electronics
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• v.5 no.4
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• pp.329-334
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• 2005

The DSTATCOM(Distribution Static Synchronous Compensator) is one of the Custom Power Devices that can regulate voltage. The DSTATCOM operates as a shunt connected static var compensator whose capacitive or inductive output current can be controlled independent of the system voltage. The magnitude of the compensated voltage is limited by characteristics of the system and the load. Compensation capability of the DSTATCOM which can inject 1 MVAR reactive power was simulated by EMTDC under several conditions. This paper analyzes the effect of the DSTATCOM's compensation considering the length and kind of distribution line, the power factor and magnitude of the load, and the duration and magnitude of the voltage variation.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.248-250
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• 2003

Recently, electric power system's situation grows gradually so Fault Diagnosis is being complicated and is felt difficult. And ability that operator who is using electric power system must do correct judgment of power system state, and can cope at fault of power system state is required. Therefore, large size power system is divided into predefined minimum module, and define each module accident type. We use and compare defined accident type, we can know easily accident that happen forward. Therefore, large size power system using module that is defined to each section common accident type search in this paper. Therefore, large size power system using module that is defined to each section, we search for common accident type. And when accident in electric power system happens, I wish to explain about process that can do fault diagnosis in more easy and fast time, because using accident type that it is verified in front.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.452-460
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• 2007

The interstate electric power system, as an alternative for energy cooperation under regional economic block, was fervently debated prior to the restructuring of electric power industries and rapidly expanded in many regions since the 1990s. Especially, electric power system interconnection in the Northeast Asia region may bring considerable economic benefits since this region has strong supplementation in resource holdings, load shape, fuel mix, and etc. In this paper, we implement the ORIRES model, proposed by ESI of Russia, in order to analyze the economic feasibility on the Northeast Asia Region Electrical System Ties (NEAREST) project.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.187-189
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• 2006

Compensators need to keep the voltage properly at the KEPCO system in a ruddle-long term point of view. Therefore, it is necessary to forecast the amount of compensators. In this paper, we analyze how much compensators are needed and what kind of effects is given on the KEPCO system in a middle-long term point of view. In addition, this analysis is based on the books named "The plan of Transmission and Substation at the KEPCO in 2005" and we used PSS/E program when we analyze the KEPCO system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.277-278
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• 2006

As a development of technology, electric power steering system which uses an electric motor came to use in recent and it can solve the problems with hydraulic power steering system. In this paper, vehicle model and electric power steering system are combined to fulfill full vehicle model. By simulation effect of motor torque assist through electric power steering revealed effective, and full vehicle model are proved reasonable through comparison with real car experimental datum.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.177-178
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• 2006

The enhancement of system security is one of the most important objectives of UPFC operation. To describe the system security, the index related to line flows and bus voltages are used. For the enhancement of security, the operation point of UPFC is set to minimize the index. This paper proposes the minimization algorithm using the Marquardt method. Moreover, the coefficients minimizing iteration number will be derived. For verification of the proposed operation scheme, numerical simulations have been performed on power system in Kwanju area, Korea with a UPFC.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.129-133
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• 2015

This paper presents the dosimetry of a resonance-based wireless power transfer (RBWPT) system for electric vehicles applications. The compact RBWPT system is designed to transfer power at 150-mm distance. The electric and magnetic fields generated by the RBWPT system and the specific absorption rate in the human body model, which stands around the system, are calculated. These analyses are conducted in two cases: the alignment and the misalignment between the transmitter and the receiver. The matching loops are adjusted to maximize the power transfer efficiency of the RBWPT system for the misalignment condition. When the two cases were compared for the best power transfer efficiency, the specific absorption rates (SAR) in the misalignment case were larger than those in the alignment case. The dosimetric results are discussed in relation to the international safety guidelines.