• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.957-960
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• 2003

Many solar cell way need to be connected by series or parallel to extract the high power Especially, during parallel operation to reduce circulation current the individual converter has to share and control the load current. Generally, Current Sharing(CS) can be implemented using droop and active current sharing method. In this paper, one 3[KW] PWM converter was replaced as one 3[KW] solar cell array(3 parallels, each parallel has twenty single modules), two 3[KW] solar cell way Is Paralleled to generate 6[KW] power. Also each converter used voltage-current controller and Automatic MSCPM(Master-Slave Current-programming Method) for current sharing(AS).

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.90-94
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employes active and reactive power control or frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employes a instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Futhermore, the proposed control scheme is verified through the simulation in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.176-181
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• 1998

The parallel inverter is popularly used because of its fault-tolerance capability, high-current outputs at constant voltages and system modularity. The conventional parallel inverter usually employs active and reactive power control of frequency and voltage droop control. However, these approaches have the disadvantages that the response time of parallel inverter control is slow against load and system parameter variation to calculate active, reactive power, frequency and voltage. This paper describes a novel control scheme for power equalization in parallel-connected inverter. The proposed scheme has a fast power balance control response, a simplicity of implementation, and inherent peak current limiting capability since it employees an instantaneous current/voltage control with output voltage and current balance and output voltage regulation. A design procedure for the proposed parallel inverter controller is presented. Furthermore, the proposed control scheme is verified through the experiment in various cases such as the system parameter variation, the control parameter variation and the nonlinear load condition.

• 설비공학논문집
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• 제13권8호
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• pp.730-738
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• 2001

This work discusses the pressure droop, heat and mass transfer of the finned-tube heat exchangers having 7 mm tubes and offset strips in dehumidifying applications. It focuses on the fin material saving and the reduction of pressure drop. The experiment was conducted using three times scaled-up models to simulate the performance of the prototype. Eight kinds of fins having different strips and S shape edges were tested. the area density of the strip was a major factor and its shape and the location were secondary factors on the pressure drop, the heat and mass transfer. The reduced-area fin can almost equal the non-reduced fin in the aspect of heat and mass transfer. The strip fins proposed in the present work can considerably reduce both the pressure drop and the fin material for similar thermal load.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.118-119
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• 2013

마이크로그리드 독립 운전 모드시 분산전원 기반의 인버터 병렬 운전은 인버터가 전압원과 같이 정의됨에 따라 계통과의 연결없이 병렬 연결된 인버터가 전체 부하를 담당해야 하는 의무를 가진다. 이때 드룹 방식은 병렬형 인버터 각각에 적용됨으로써 전체 부하 분담성능을 향상시킨다. 하지만 각 분산전원과 PCC단을 연결하는 선로 임피던스가 불평형 이거나 서로 다른 R/X 비를 가지고 있을때 유도성 선로에 적용을 목적으로 하는 기존의 드룹 방식을 사용하면 유효전력 분담은 어느 정도의 효력을 보이지만 무효 전력 분담에 있어서 오차가 발생하게 된다. 이와 반대로 저항성 선로에 적용을 목적으로 하는 드룹 방식을 적용하면 무효 전력 분담은 잘 이루어지지만 유효 전력 분담은 서로 다른 선로 임피던스 전압 강하로 인해 오차가 발생하게 된다. 따라서 본 논문에서는 PSIM을 활용하여 고, 중, 저전압 마이크로그리드 뿐만 아니라 R성분이 매우 지배적인 초저전압 마이크로그리드에 각기 다른 드룹 방식을 적용할때의 영향을 분석하고 이에 제안된 선로 임피던스를 고려한 기준 전압 조정텀을 추가하여 유효, 무효 전력 분담 오차를 개선하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.14-15
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• 2013

본 논문에서는 컨버터의 병렬운전을 하는데 있어 제안한 드룹제어를 사용하여 전력을 분담한다. 제안한 방법을 이용하면 직류배전에서 병렬시스템의 용량증설을 용이하게 할 수 있다. 기존의 교류전원에서 사용하는 드룹 제어 방법을 새롭게 개선하여 직류전원에서 드룹 제어가 적용되도록 드룹 제어기를 설계한다. 그리고 제안한 드룹 제어기의 제어방법을 상세히 설명한다. 본 논문에서는 제안한 제어방법을 50[kW] 직류배전 시스템에 적용하여 시뮬레이션을 통하여 제안된 기법의 타당성을 검증한다.

• 대한전기학회논문지:전력기술부문A
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• 제54권11호
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• pp.540-547
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• 2005

One of the roles of AGC is to regulate the frequency of power systems. AGC is also used to control the frequency of Korean Power System. AGC control strategies depend on system characteristics and the requirements of the systems to which those are applied. Korean Power System consists of one control area and does not have tie-lines. In this research, an AGC control strategy is suggested to avoid conflict with governor dynamics and to enhance frequency recovery It shows good performance for regulation and frequency recovery. This control strategy is expected to be applied to New EMS in KPX to get reasonable AGC regulation and frequency recovery performance.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1998년도 제10회 학술강연회논문집
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• pp.4-4
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• 1998

이 연구에서는 100인승 항공기 급의 저익-주익장착나셀(wing mounted nacelle)의 추진기관 장착설계 방법을 제시하였다. 장착설계 방법을 구체적으로 설명하기 위해 세부적인 설계제한조건(design constraint)과 설계요구조건(design requirement and objectives)을 정의하고, 그러나 기준을 근거로 실례의 항공기(K100)를 사용하여 주익장착방식의 장착설계를 수행하였다. 장착설계는 간접항력(interference drag), roll clearance, ground clearance, nose gear collapse margin, rotor burst, 연료탱크용량 등의 설계제한 사항들을 고려하여 엔진성능을 만족시킬 수 있는 최적의 나셀 장착위치(spanwise, FS, WL)와 장착각도(toe-in, incidence, droop angle), wing day의 위치와 크기를 결정하여 향후에 개발될 주익장착방식의 추진기관 장착설계에 활용될 수 있는 설계절차를 구축하였다.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.292-298
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• 2012

The epitaxial layer structures for blue InGaN light emitting diodes have been optimized for high brightness applications with the output power levels exceeding 1000 $W/cm^2$ by using a self-consistent finite element method. The light-current-voltage relationship has been directly estimated from the multiband Hamiltonian for wurtzite crystals. To analyze the efficiency droop at high injection levels, the major nonradiative recombination processes and carrier spillover have also been taken into account. The wall-plug efficiency at high injection levels up to several thousand $A/cm^2$ has been successfully evaluated for various epilayer structures facilitating optimization of the epitaxial structures for desired output power levels.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.120-121
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• 2017

This paper proposes an enhanced distributed generation (DG) unit with an adaptive virtual impedance control approach in order to address the inaccurate reactive power sharing problem. The proposed method can adaptively regulate the DG virtual impedance, and the effect of the mismatch in feeder impedances is compensated to share the reactive power accurately. The proposed control strategy is fully distributed and the need for the microgrid central controller is eliminated. Furthermore, the proposed method can be directly implemented without requirement of pre-knowledge of the feeder impedances. Simulations are performed to validate the effectiveness of the proposed control approach.