• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.231-235
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• 2008

Thyristor rectifiers are still the preferred choice for large magnet power supplies. However, large harmonic voltages, resulting in large current ripple, and slow dynamic response are major drawbacks of these converters. Joos presented a topology and a control technique for a hybrid large-power high-precision magnet power supply in 1996. The system consists of a phase controlled rectifier (PCR) connected in series with a high-frequency PWM converter. This paper improves the power circuit of the PWM converter using interphase transformer. Simulation result proves effect of the proposed system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2167-2172
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• 2008

A large scale embedded generator or a micro-grid is usually interconnected to the grid through the dedicated line. Immediately after the removal of the grid supply, it must be disconnected and remain disconnected until the normal grid supplies are restored. This paper proposes an islanding detection algorithm based on complex power at the intertie. Complex power at the intertie delivered to the grid has a value depending on power flow during normal operation. When loss of mains occurs, complex power at the intertie moves to a value depending on the parameters of the dedicated line. The performance of the proposed algorithm was investigated under various operating and fault conditions. The proposed algorithm can detect an islanding operation even if no power is exchanged prior to loss of mains and discriminate the fault condition from islanding.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.486-487
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• 2012

In this paper, novel three-port active power decoupling (APD) method for applying 250[W] micro-inverter. This type using third port for active power decoupling stores the surplus energy and supplies sufficient energy to grid. Conventional decoupling circuit is applied in single phase grid connected micro-inverter especially single-stage configuration like flyback-type DC-AC inverter. In this passive power decoupling method, electrolytic capacitor with large capacitance is needed for decoupling from constant DC power and instantaneous AC power. However the decoupling capacitor is replaced with film capacitor by using APD, thus the overall system can achieve smaller size and long lifespan. Proposed three-port flyback inverter is verified by design and simulation.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.138-142
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• 2004

Recently over dropped frequencies of power system were recorded when power system was unbalanced between generation and demand. Therefore load following characteristic analysis of thermal and combined cycle power plant generators is necessary for low frequency condition analysis of power system. Frequency simulator supplies simulated frequency to the online generator for prescribed goal. This simulator needs to minimize effects to power system and requires stability first. This paper introduces design and manufacturing case of frequency simulator for load following characteristic analysis of generators.

• Journal of Power Electronics
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• v.1 no.2
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• pp.65-70
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• 2001

Transmission System Operators are governed by operational security standards that are applied in real time. During system disturbances, the System Operators must rely on the installed protection and control equipment, prior to human intervention. New power electronic solutions bring rapid and repeatable responses to disturbances, which will help System Operators to guarantee a stable system. Last year, Alstom completed the world's first competitively bid STATCOM to support the voltage on National Grid's 400kV network that supplies London and the Southeast from the north of the UK. It is rated ${\pm}75MVAr$ and forms part of a Static Var System (SVS) with a total rating of 0 to 225MVAr. This paper will describe the reasons for its size, location, its chain-link configuration and give examples of its operating performance. The paper will also describe the features that allow this STATCOM to deliver much more than reactive compensation in support of a wider transmission service objective, as system conditions require.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1342-1344
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• 2002

Wind is a significant and valuable renewable energy resource. It is safe and abundant and can make an important contribution to future clean, sustainable and diversified electricity supplies. Unlike other sources of energy, wind does not pollute the atmosphere nor create any hazardous waste. In some countries wind energy is already competitive with fossil and nuclear power even without accounting for the environmental benefits of wind power. The cost of electricity from conventional power stations does not usually take full account of its environmental impact (acid rain, oil slick clean up, the effects of climate change, etc). In this paper, a transient phenomenon simulation method for Wind Power Generation System(WPGS) under real weather conditions has been proposed. The simulation method is expected to be able to analyze easily under various conditions with considering the sort of wind turbine, the capacity of system and the converter system. Wind turbine connected to the synchronous generator and power converter was simulated.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.3-32
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• 2016

High power impulse magnetron sputtering (HiPIMS) technique has been developed for more than 15 years. It is characterized by its ultra-high peak current and peak power density to obtain unique thin film properties, such as high hardness, good adhesion and tribological performance. However, its low deposition rate makes it hard to be applied in industries. In this work, the development of HiPIMS system and integration of radio frequency (RF) or mid-frequency (MF) power supplies were introduced. Effects of duty cycle and repetition frequency on the microstructure, mechanical property, optical and electrical properties of some binary, ternary and quarternary nitride coatings and oxide thin films were discussed. It can be observed that the deposition rate was effectively increased by the superimposed HiPIMS with RF or MF power. High hardness, good adhesion and sufficient wear resistance can be obtained through a proper adjustment of processing parameters of HiPIMS power system.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.431-434
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• 1999

This paper presents design of controllers for battery energy storage system. The proposed battery energy storage system can be controlled to operate in the power conditioning mode or the inverter mode. The operation of this mode further divided into three cases: (a) in the peak load period, the load power supplied from the utility is minimized as far as possible; (b) in the off-peak load period, the utility supplies power to the load and charges the battery bank with automatic charging control; (c) in the medium load period, to save battery energy the real power flow out of the battery energy storage system is minimized. Besides, in all cases, the proposed battery energy storage system also automatically compensates the harmonics, subharmonics and reactive power factor in the utility side are much improved. Simulation results are presented by the effectiveness of the proposed controllers for battery energy storge system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.192-197
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• 2005

This paper presents a development of the auxiliary power supply simulator for a electric rolling stock. An auxiliary power supplies are required for operating air conditioning units, ventilation fans, lighting and battery charging. Traditionally this function has been fulfilled by Motor-Alternator sets. In recent years, high performance of semiconductor and micro processor, availability and price have made three phase voltage source inverters as an attractive alternative to MA Sets. From the baseline model of the SIV(Static InVerter) for electric rolling stock, we designed the scale down model of the auxiliary power supply simulator consisting of an IGBT three phase voltage source inverter. The auxiliary power supply simulator can be used educatory purpose for training efficiently about operating principles of SIV.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.99-103
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• 2002

IEC 61800 is an international standard on adjustable speed electrical power drive systems, which consists of three parts. IEC 61800-1 and IEC 61800-2 apply to DC power drive systems and AC power drive systems, respectively, which include power conversion, control equipment, and also a motor or motors. IEC 61800-3 specifies EMC ( Electro Magnetic Compatibility ) requirements for adjustable speed AC or DC motor drives connected to main supplies up to AC 1,000 volts. This paper studies the standards related to EMC and the text summary of international standard IEC 61800-3 which is an EMC product standard including specific test methods.