• 한국초전도ㆍ저온공학회논문지
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• 제4권1호
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• pp.61-65
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• 2002

It becomes difficult and high in cost to construct new ducts and/or tunnels for power cables in metropolitan areas. This paper presents possible applications of an HTS superconducting power cables for transmitting electric power in metropolitan areas. Reflected were its important distinction such as compactness for installation in underground ducts and considerably high efficiency compared with present underground cables. In this paper, system modeling, transmission capacity and voltage class of compact HTS cables which should be applied to existing ducts were reviewed. Based on this, the following items on urban transmission system are examined. (1) A method of constructing a model system to introduce high temperature superconducting cables to metropolitan areas is presented. (2)The maximum outer diameter of HTS cables to be accommodated in exiting ducts is calculated based on the design standards for current cable ducts. (3)The voltage level that can be accommodated by existing ducts is examined.

• KIEE International Transactions on Power Engineering
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• 제2A권4호
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• pp.136-144
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• 2002

Load models are very important for improving the accuracy of stability analysis and load flow studies. Various loads are connected to a power bus and their characteristics of power consumption change with voltage and frequency. Thus, the effect of voltage/frequency changes must be considered in load modeling. In this work, artificial neural networks-ANNs- were used to construct the component load models for more accurate modeling. A typical residential load was selected and subjected to a test under variable voltage/frequency conditions. Acquired data were used to construct component models by ANNs. The aggregation process of separately determined load models is also presented in the paper. Furthermore, this paper proposes a method to transform a single load model constructed by the aggregation method into a mathematical load model that can be used in traditional power system analysis software.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1137-1142
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• 2008

In this paper, an effect on power conversion unit in high-speed railway vehicle by loss of contact between a catenary system and pantograph suppling electrical power to high-speed railway vehicle are investigated. One of the most important needs accompanied by increasing the speed of high-speed railway vehicle is reduced that arc phenomenon by loss of contact brings out EMI. in case of high-speed railway vehicle using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occur. To analysis the effect on loss of contact, it is necessary electrical modeling system between the contact line and the pantograph according to the loss of contact. Therefore analytical model of a contact line and a pantograph is constructed to simulate the behaviour of loss of contact. The reliability of the modeling system is verified by simulation implementation on kinds of loss of contact.

• Journal of Electrical Engineering and Technology
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• 제4권1호
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• pp.35-42
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• 2009

When two adjacent AC systems operate at different frequency such as 50Hz and 60Hz, as in the case of ROK and Russia, the only way to practically obtain the advantages of power system interconnection is to use HVDC connection. In this paper, application of the VSC-HVDC transmission for power system interconnection between Russia and ROK is evaluated through the PSCAD/EMTDC modeling and analysis. The simulation results show the feasibility of proposed system for cross border power system interconnection.

• Journal of Power Electronics
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• 제19권2호
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• pp.519-528
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• 2019

The unified power quality conditioner (UPQC) is an effective custom power device that is used at the point of common coupling to protect loads from voltage and current-related PQ issues. Currently, most researchers have studied series unit and parallel unit models and an idealized transformer model. However, the interactions of the series and parallel converters in AC-link are difficult to analyze. This study utilizes an equivalent transformer model to accomplish an electric connection of series and parallel converters in the AC-link and to establishes a precise unified mathematical model of the UPQC. The strong coupling interactions of series and parallel units are analyzed, and they show a remarkable dependence on the excitation impedance of transformers. Afterward, a feed-forward decoupling method based on a unified model that contains the uncertainty components of the load impedance is applied. Thus, this study presents an adaptive method to estimate load impedance. Furthermore, simulation and experimental results verify the accuracy of the proposed modeling and decoupling algorithm.

• 대한전기학회논문지:전력기술부문A
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• 제55권7호
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• pp.281-289
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• 2006

Advanced controllers among Flexible AC Transmission System(FACTS) devices employ self-commutated switching converters, VSI (Voltage Sourced Inverters), as the synchronous voltage source. Such controllers are SSSC (Static Synchronous Series Compensator), STATCOM (Static Synchronous Compensator) and UPFC (Unified Power Flow Controller). UPFC is series-shunt combined controller. Its series and shunt inverters can be modeled as SSSC and STATCOM but the dependant relation between the inverters is very complex. For that reason, the complexity makes it difficult to develop the UPFC model by simply combining the SSSC and STATOM models when we apply the model for conventional power system dynamic simulation algorithm. Therefore, we need each relevant models of VSI type FACTS devices for power system analysis. This paper proposes a modeling approach which can be applied to modeling of VSI type FACTS devices. The proposed method using Newton-type current injection method can be used to make UPFC, SSSC, and STATCOM models. The proposed models are used for 2-area test system simulation, and the results verify their effectiveness.

• Journal of Power Electronics
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• 제19권1호
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• pp.288-295
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• 2019

Rectifiers are widely used in industrial applications. Although detailed models of rectifiers are usually used to evaluate their performance, they are complex and time-consuming. Therefore, the Average Value Model (AVM) has been introduced to meet the demand for a simple and accurate model. This type of rectifier modeling can be used to simplify the simulations of large systems. The AVM of diode rectifiers has been an area of interest for many electrical engineers. However, healthy diode rectifiers are only considered for average value modeling. By contrast, faults occur frequently on diodes, which eventually cause the diodes to open-circuit. Therefore, it is essential to model bridge rectifiers under this faulty condition. Indeed, conventional AVMs are not appropriate or accurate for faulty rectifiers. In addition, they are significantly different in modeling. In this paper, a novel application of the parametric average value of a three-phase line-commutated rectifier is proposed in which one diode of the rectifier is considered open-circuited. In order to evaluate the proposed AVM, it is compared with experimental and simulation results for the application of a brushless synchronous generator field. The results clearly demonstrate the accuracy of the proposed model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.144-146
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• 1998

In this study Dead time equivalent resistance of Voltage source power converter is very important in current controller design. And Non-linear Modeling method can be applied in Power converter analysis. Using Describing Function method and Non-linear Resistance Modeling. Voltage Source Power Converter Bode diagram and Current controller analysis method are more reality.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.95-97
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• 2007

Transformer inrush current can cause the voltage drop by source impedance. The accurate modeling and analysis for inrush current is first step to limit the inrush current and improve the power qualify. This paper presents the modeling of transformer inrush current by EMTP-RV using Jeju power system, Korea. The method to model the hysteresis curve of transformer in EMTP-RV is discussed. Simulations demonstrate the verification of modeling of inrush current by comparing the data recorded in field with simulation values and analyzing the harmonics of inrush current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.610-614
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• 2004

Recently, an active-clamp, full-bridge boost converter has been actively studied for high-power applications such as power factor correction and battery discharger. However, DC and AC modeling for this converter has not conquered. In this paper, a DC and small-signal AC modeling for the active-clamp, full-bridge boost converter is described. Based on the operation principle, the ac part of the converter can be replaced by a do counterpart. Then, a conceptual equivalent circuit is derived by rearranging the switches. The equivalent circuit for this converter consists of CCM (Continuous conduction mode) boost and DCM (Discontinuous conduction mode) buck converter. The analyses for the equivalent CCM boost and DCM buck converter are done using the model of PWM switch. The theoretical modeling results are confirmed through experiment or SIMPLIS simulation.