• 대한전기학회논문지:전력기술부문A
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• 제49권12호
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• pp.581-588
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• 2000

This paper presents the power system application of a PWM base UPFC through EMTP simulation. A PWM base UPFC model is constructed and detailed switching-level simulation is performed using EMTP. The dynamic responses of UPFC are analyzed. Based on the simulation results, the appropriate equivalent impedances of UPFC voltage-source model which represent similar dynamics with PWM based UPFC are determined by optimization routine. This paper also analyzes the influence of the power system strength on the dynamic responses of UPFC. Finally this paper shows that the performance of UPFC is improved by control parameter tuning when UPFC is installed to weak power system.

• 한국생산제조학회지
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• 제22권3호
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• pp.364-371
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• 2013

Because of the increases in international oil prices and the level of global warming, the automotive industry has much interest in developing green cars with high fuel efficiencies. In addition, researchers in Korea are actively responding to high oil prices and $CO_2$ emission regulations in many ways. One example is, the multi-mode hybrid system, which is being studied to improve its performance. Because a multi-mode hybrid system is able to overcome the weaknesses of a system that uses simple planetary gears, excellent fuel efficiency and driving performances are the key features of the system. This paper analyzes the driving performance of the power-train system of GM-2MT70, which consists of one engine, two electric motors, one simple planetary gear, one double planetary gear, two clutches, and two brakes. The driving performance of the system's steady state is analyzed using performance modeling. The dynamic performance is analyzed using Matlab Simulink.

• Journal of Power Electronics
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• 제18권1호
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• pp.34-44
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• 2018

This paper presents a pulse-width adjustment (PWA) strategy for a novel bidirectional DC-DC boost converter to improve the performance of the dynamic inductor current response. This novel converter consists of three main components: a full-bridge converter (FBC), a high-frequency isolated transformer with large leakage inductance, and a three-level voltage-doubler rectifier (VDR). A number of scholars have analyzed the principles, such as the soft-switching performance and high-efficiency characteristic, of this converter based on pulse-width modulation plus phase-shift (PPS) control. It turns out that this converter is suitable for energy storage applications and exhibits good performance. However, the dynamic inductor current response processes of control variable adjustment is not analyzed in this converter. In fact, dc component may occur in the inductor current during its dynamic response process, which can influence the stability and reliability of the converter system. The dynamic responses under different operating modes of a conventional feedforward control are discussed in this paper. And a PWA strategy is proposed to enhance the dynamic inductor current response performance of the converter. This paper gives a detailed design and implementation of the PWA strategy. The proposed strategy is verified through a series of simulation and experimental results.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.85.1-85
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• 2001

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.139-142
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• 1987

It is important to evaluate the voltage characteristics of diesel generator as an emergency power supply in nuclear power plant. On loss of offsite power sources, emergency safeguard loads required to safely shutdown the reactor should be supplied by diesel generator. This paper presents the dynamic stability program to evaluate diesel generator performance as an emergency power system. The results Indicate the diesel generator ability to start the motors successfully seems to life in its impedances and inertias.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권1호
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• pp.37-47
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• 2018

Dynamic simulation is critical for electrical ship studies as it obtains the necessary information to capture and characterize system performance over the range of system operations and dynamic events such as disturbances or contingencies. However, modeling and simulation of the interactive electrical and mechanical dynamics involves setting up and solving system equations in time-domain that is typically time consuming and computationally expensive. Accurate assessment of system dynamic behaviors of interest without excessive computational overhead has become a serious concern and challenge for practical application of electrical ship design, analysis, optimization and control. This paper aims to develop a systematic approach to classify the sophisticated dynamic phenomenon encountered in electrical ship modeling and simulation practices based on the design intention and the time scale of interest. Then a novel, comprehensive, coherent, and end-to-end mathematical modeling and simulation approach has been developed for the latest Medium Voltage Direct Current (MVDC) Shipboard Power System (SPS) with the objective to effectively and efficiently capture the system behavior for ship-wide system-level studies. The accuracy and computation efficiency of the proposed approach has been evaluated and validated within the time frame of interest in the cast studies. The significance and the potential application of the proposed modeling and simulation approach are also discussed.

• 동력기계공학회지
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• 제21권2호
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• pp.35-40
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• 2017

In this study, the multi-body dynamics model for a wave energy converter is established. The equations of motions for the mechanical parts of the wave energy converter are derived to analyze the dynamic behavior. A spring method with the same performance as the counter weight method is proposed. The counter weight method and spring method are analyzed for evaluating the performance of the wave energy converter. RecurDyn program which is a kind of commercial multi-body dynamics program is used to perform the dynamic simulation of the wave energy converter.

• 전력전자학회논문지
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• 제5권4호
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• pp.318-326
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• 2000

수전단의 관성이 0(수전단에 발전력이 전혀 없는 경우)인 약한 계통에서는 HVDC가 재기동과 무효전력 보상을 위해서 동기조상기의 존재는 필수적이다. 동기조상기와 주된 목적이 무효전력올 보상하는 것이지만 SVC나 STACON과 같은 무효전력 보상장치는 HVDC시스템을 재기동(HVDC에서는 Black-Start라 부른다)시킬 수 있는 능력을 가지고 있지 못하지 때문에 동기조상기가 발전력이 없는 약한 계통에서는 유일한 대안이다. 동기조상기는 발전기의 일종으로서 무효전력을 조정하는 여자 시스템의 종류에 따라 다른 특성을 가지고 있다. 정지형 여자 시스템은 속응성과 보수 유지의 간편성 때문에 많아 각광받고 있는 형태임에도 불구하고 시스템이 가지고 있는 본질적인 결함 때문에 약한 계통에 연결된 경우에는 짧은 문체점을 노출시키고 있다. 반면에 AC 회천형 여자 시스템은 속응성에 낮음에도 불구하고 여자기의 공급전원이 안정하다는 장점올 가지고 있다. 본 논문에서는 이러한 여자 시스템의 장단점을 분석하고 정지형 여자 시스템의 장점과 AC 회전형 여자 시스템의 장점올 결함한 새로운 여자 시스템올 제안하였다. 제안된 시스템은 HVDC 시스템에 연결된 경우에 좋은 제어 특성을 보여 주었으며 결과는 PSCAD/EMTDC를 이용하여 확인하였다.

• Ocean Systems Engineering
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• 제3권3호
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• pp.203-217
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• 2013

A PTO (power-take-off) mechanism by using relative heave motions between a floating buoy and its inner mass (magnet or amateur) is suggested. The inner power take-off system is characterized by a mass with linear stiffness and damping. A vertical truncated cylinder is selected as a buoy and a special station-keeping system is proposed to minimize pitch motions while not affecting heave motions. By numerical examples, it is seen that the maximum power can actually be obtained at the optimal spring and damper condition, as predicted by the developed WEC(wave energy converter) theory. Then, based on the developed theory, several design strategies are proposed to further enhance the maximum PTO, which includes the intentional mismatching among heave natural frequency of the buoy, natural frequency of the inner dynamic system, and peak frequency of input wave spectrum. By using the intentional mismatching strategy, the generated power is actually increased and the required damping value is significantly reduced, which is a big advantage in designing the proposed WEC with practical inner LEG (linear electric generator) system.

• 전력전자학회논문지
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• 제18권1호
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• pp.54-62
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• 2013

This paper proposes a high-efficiency DC-DC converter with improved dynamic response characteristics for modular photovoltaic power conversion. High power efficiency is achieved by reducing switching power losses of the DC-DC converter. The voltage stress of power switches is reduced at primary side. Zero-current switching of output diodes is achieved at secondary side. A modified proportional and integral controller is suggested to improve the dynamic responses of the DC-DC converter. The performance of the proposed converter is verified based on a 200 [W] modular power conversion system including the grid-tied DC-AC inverter. The proposed DC-DC converter achieves the efficiency of 97.9 % at 60 [V] input voltage for a 200 [W] output power. The overall system including DC-DC converter and DC-AC inverter achieves the efficiency of 93.0 % when 200 [W] power is supplied into the grid.