• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1643-1653
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• 2014

This paper presents the design and implementation of a wind-solar hybrid power system for LED street lighting and an isolated power system. The proposed system consists of photovoltaic modules, a wind generator, a storage system (battery), LED lighting, and the controller, which can manage the power and system operation. This controller has the functions of maximum power point tracking (MPPT) for the wind and solar power, effective charging/discharging for the storage system, LED dimming control for saving energy, and remote data logging for monitoring the performance and maintenance. The proposed system was analyzed in regard to the operation status of the hybrid input power and the battery voltage using a PSIM simulation. In addition, the characteristics of the proposed system's output were analyzed through experimental verification. A prototype was also developed which uses 300[W] of wind power, 200[W] of solar power, 60[W] LED lighting, and a 24[V]/80[Ah] battery. The control system principles and design scheme of the hardware and software are presented.

• Journal of Power Electronics
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• v.19 no.4
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• pp.881-893
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• 2019

This paper proposes a practical sliding-mode controller design for shaping the impedances of cascaded boost-converter power decoupling circuits for reducing the second order harmonic ripple in photovoltaic (PV) current. The cascaded double-boost converter, when used as power decoupling circuit, has some advantages in terms of a high step-up voltage-ratio, a small number of switches and a better efficiency when compared to conventional topologies. From these features, it can be seen that this topology is suitable for residential (PV) rooftop systems. However, a robust controller design capable of rejecting double frequency inverter ripple from passing to the (PV) source is a challenge. The design constraints are related to the principle of the impedance-shaping technique to maximize the output impedance of the input-side boost converter, to block the double frequency PV current ripple component, and to prevent it from passing to the source without degrading the system dynamic responses. The design has a small recovery time in the presence of transients with a low overshoot or undershoot. Moreover, the proposed controller ensures that the ripple component swings freely within a voltage-gap between the (PV) and the DC-link voltages by the small capacitance of the auxiliary DC-link for electrolytic-capacitor elimination. The second boost controls the main DC-link voltage tightly within a satisfactory ripple range. The inverter controller performs maximum power point tracking (MPPT) for the input voltage source using ripple correlation control (RCC). The robustness of the proposed control was verified by varying system parameters under different load conditions. Finally, the proposed controller was verified by simulation and experimental results.

• Journal of Power Electronics
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• v.6 no.3
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• pp.226-234
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• 2006

Photovoltaic (PV) generators have nonlinear V-I characteristics and maximum power points which vary with illumination level and temperature. Using a maximum power point tracker (MPPT) with an intermediate converter can increase the system efficiency by matching the PV systems to the load. This paper presents a maximum power point tracker based on fuzzy logic and a control scheme for a single-phase inverter connected to the utility grid. The fuzzy logic controller (FLC) provides an adaptive nature for system performance. Also the FLC provides excellent features such as fast response, good performance and the ability to change the fuzzy parameters to improve the control system. A single-phase AC-DC inverter is used to connect the PV system to the grid utility and local loads. While a control scheme is implemented to inject the PV output power to the utility grid at unity power factor and reduced harmonic level. The simulation results have shown the effectiveness of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.358-361
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• 2006

태양전지는 일사량에 따라 그 출력특성이 변하기 때문에 전지로부터 최대출력을 얻기 위해서는 컨버터에 의한 최대 전력점 추종제어가 필요하다. 본 논문에서는 태양광 발전시스템의 최대전력추종을 위해 퍼지이론을 도입한 퍼지제어기를 설계하였다. 퍼지제어기의 디지털 설계를 위해 태양광 발전시스템을 각 부분을 구성하고, FPGA를 사용하여 제어기를 구현하였다. 또한 실험을 통해 FPGA의 퍼지제어기로서의 구현가능성을 발견하고 그 타당성을 입증하고자 한다.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.51-54
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• 2005

Generator efficiency optimization is important for economic saving and environmental pollution reduction. In general, the machine loss can be reduced by the decreasing the flux level, resulting in the significant reduction of the core loss. This paper proposesan model-based controller is used to decrement the excitation current component on the basis of measured stator current and machine parameters and the q-axis current component controls the generator torque, by which the speed of the induction generator iscontrolled according to the variation of the wind speed in order to produce the maximum output power. The generator reference speed is adjusted according to the optimum tip-speed ratio. The generated power flows into the utility grid through the back-to-back PWM converter. The grid-side converter controls the dc link voltage and the line-side power factor by the q-axis and the d-axis current control, respectively. Experimental results are shown to verify the validity of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.155-157
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• 2006

현재 화석연료에만 의존하는 에너지 시장을 변화시키고자 하는 연구가 활발히 이루어지고 있는 가운데 신재생에너지(연료전지, 풍력, 태양광 등)를 복합적으로 활용한 분산전원시스템에 관한 관심이 증가하고 있다. 이 가운데 풍력 발전시스템은 발전효율, 가격측면 등에 있어 많이 연구되고 있다. 그러나 풍력발전시스템의 경우 난류가 되기 쉽고, 풍향이나 풍속이 수십초의 간격으로 변화하기 때문에, 바람의 에너지를 최대한 이용하는 최대전력점추종(MPPT)제어기의 역할이 가장 중요하다. 본 논문에서는 소형풍력발전기를 활용하여 풍속, 풍차 회전속도, 전력 등의 정보를 이용한 기존 방식에 비하여 아주 간단한 제어기법을 구현하고자 한다.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.665-669
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• 2000

Recently the problem of energy branch become worse increasingly. Therefore many researches about new energy source are processing in several places around are processing in several places around the world. Especially solar energy has many advantages like as purity and infinity. Photovoltaic(PV) system can be classified into two types : One is stand alone type and the other is utility interactive one. Utility interactive type PV system need some technology that Maximum peak power tracking(MPPT) and Anti-islanding and Active Power filter(APF). For APF operation dc-link voltage should be high to supply sufficient output current which needed for harmonic current compensation so usually DC-DC converter is used for boost. In this paper DC-DC converter for PV system and controller for dc-link voltage control are analyzed and designed.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.341-348
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• 2003

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique ta continuously deliver the highest possible power to the load when variations in the insolation and temperature occur. A simple method of tracking the maximum power points (MPPs) and forcing the boost converter system to operate close to these points is presented through deriving small-signal model and transfer function of boost converter. This paper aims at modeling boost converter including equivalent series resistance of input reservoir capacitor by state-space-averaging method and PWM switch model with properly designed controller for maximum photovoltaic power tracking control.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1019_1020
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• 2009

본 논문은 다수의 독립형 태양광 발전 시스템의 디지털 제어에 대해 제안한다. 제안된 시스템은 에너지를 발생하는 태양전지, 최대전력점을 추종(MPPT)하도록 하는 Boost컨버터, 부하에 적합한 준위의 전압을 공급하는 Buck컨버터로 구성되어 있으며, 태양전지 어레이를 분할하여 제어하므로 Boost컨버터가 태양전지 어레이가 분할 된 만큼 추가된다. 제안된 방법은 디지털 제어기의 제어변수 값 들을 바꿈으로써 전체시스템의 출력특성을 쉽게 제어할 수 있어 사용되는 태양전지 어레이의 종류와 환경조건 변화에 따라 쉽게 제어변수 값들을 조정할 수 있다. 또한 하나의 디지털 제어기로 다수의 태양광 시스템을 제어하므로 고가의 디지털 제어기의 개수를 줄여 비용이 저렴한 장점이 있다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1211-1217
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• 2007

In this paper, a 10kVA PV inverter applying Incremental Conductance(IncCond) method for maximum power point tracking WIS developed and its performance tests were carried out. Modeling and simulation of PV array and system controller was performed using PSCAD/EMTDC, an electromagnetic transient analysis program. After comparison and analysis of Perturbation & Observation (P & O) and IncCond method, a PV inverter based on IncCond method was designed and manufactured. Grid interface transient characteristics including start-up, normal operation, and fault operation were tested, which verified the usefulness of the proposed system. In the near future, commercialization process will proceed through additional extensive tests of transients.