• 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.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.59-63
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• 2005

The 800-kW PM (permanent magnet) synchronous generator is developed as a wind power generator. The matching converter is designed to control the torque and power depending on the wind speed regime. The generator starts to generate the power at the speed of 9 rpm and the rated output is generated at the speed of 25 rpm. The rated output power of an inverter is 750 kW when the PM synchronous generator is delivering 800 kW to the inverter. The inverter is specially designed to perform the maximum power point tracking (MPPT) at the low wind speed regime that is typical wind environment in Korea. The inverter test was done with a 2 MW M-G system at KERI (Korea Electric Research Institute). The M-G set has a 2 MW motor driver and a 38:1 gear to match the speed between the motor and the PM generator. The torque simulating the wind is applied to the PM generator by a DC motor. The test results show the inverter efficiency of $94.3\%$ at the rated power generating condition. The measured values show that the MPPT algorithm is working well. Overall reliability will be verified through the long-term site test.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.6
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• pp.695-701
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• 2018

For a power grid that has a high wind penetration level, when wind speeds are continuously fluctuating, the maximum power point tracking (MPPT) operation of a variable-speed wind turbine (VSWT) causes the significant output power fluctuation of a VSWT, thereby significantly fluctuating the system frequency. In this paper, an improved power-smoothing scheme of a VSWT is presented that significantly mitigates the frequency fluctuation caused by varying wind speeds. The proposed scheme employs an additional control loop based on the frequency deviation that operates in combination with the MPPT control loop. To improve the power-smoothing capability of a VSWT in the over-frequency section (OFS), the control gain of the additional loop, which is set to be inversely proportional to the rotor speed, is proposed. In contrast, the control gain in the under-frequency section is set to be proportional to the rotor speed to improve the power-smoothing capability while avoiding over-deceleration of the rotor speed of a VSWT. The proposed scheme significantly improves the performance of the power-smoothing capability in the OFS, thereby smoothing the frequency fluctuation. The results clearly demonstrate that the proposed scheme significantly mitigates the frequency fluctuation by employing the different control gain for the OFS under various wind penetration scenarios.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.527-529
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• 2007

본 논문에서는 120kW급에 이어 단일용량 200kW급 태양광발전용 계통연계형 인버터의 개발에 관한 내용을 설명하고 있다. 200kW급 계통연계형 태양광발전시스템은 22.9kV의 특고압 계통전원에 연계되도록 설계되었으며, 삼상 380V를 22.9kV로 승압 연계하는 2단 절연방식을 채택하였다. 200kW급 인버터는 상용주파수 변압기 절연방식으로 3상4선식 380V 60Hz 출력을 가지고 있으며, 인버터 내부에 200kVA급 변압기와 리액터를 포함하고 있다. 최대 전력점 추종(Maximum Power Point Tracking, MPPT)제어 기법으로 P&O 알고리즘을 적용하였으며, 3상 IGBT 인버터를 DSP로 제어하였다. 본 논문에서는 200kW급 단일용량 인버터를 개발함에 있어, 계통연계 시험, 단독운전 검출 및 방지 시험, 발전량에 따른 효율과 THD 측정 등의 결과를 보이고 있다.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.342-348
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• 2021

The PV module of solar power systems requires maximum power point tracking (MPPT) technique because the power-voltage and current-voltage characteristics vary depending on the surrounding environment. In addition, the 120 Hz ripple voltage on the DC-Link is caused by the imbalance of the system voltage and current. The effect of this 120 Hz ripple voltage reduces the efficiency of the power generation system by increasing the output current distortion rate. Increasing the capacity of DC-Link can reduce the 120 Hz ripple voltage, but this method is inefficient in price and size. We propose a technique that detects 120 Hz ripple voltage and reduces the effect of ripple voltage without increasing the DC-Link capacity through a controller. The proposed technique was verified through simulations and experiments using a 1 kW single-phase solar power system. In addition, the proposed technique's feasibility was demonstrated by reducing the distortion rate of the output current.

• Journal of IKEEE
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• v.23 no.3
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• pp.826-831
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• 2019

The stand-alone photovoltaic power systems are widely used for lighting equipment and CCTV. In order for these devices to be competitive, the life of power storage devices such as batteries is very important. The characteristic Hybrid supercapacitor is the high power density and long life. We have proposed a stand-alone photovoltaic power system that uses hybrid supercapacitor. The charge and discharge characteristics and the internal resistance of the hybrid capacitor were measured to configure the power converter. A stable maximum output point tracking control algorithm is proposed even with the change in solar radiation. In order to verify the validity of the proposed system, a prototype was fabricated and tested using a 18W hybrid capacitor and a 10W solar cell.

• Journal of the Korean Solar Energy Society
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• v.34 no.2
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• pp.1-7
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• 2014

Generally, buck converter controller is designed to control the output voltage of the converter. However, design of the controller in a photovoltaic power conditioning system is different from theoretical design guideline. The controller in a photovoltaic power conditioning system controls the input voltage of the converter (the output voltage of the solar cell) to meet a maximum power point tracking (MPPT) performance. In this study, a new model for buck converter used in a photovoltaic power conditioning system is proposed, which is linearized after state-space averaging in each period. Also, mathematical expression of the modeled buck converter is interpreted separately as small and large signals; therefore its appropriateness is measured to design linear voltage and current controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.201-210
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• 2014

In this paper, dc-link voltage control of a grid-connected QZSI is presented. Since the input current of the ZSI is discontinuous, a capacity with relatively large capacitance should be connected to the output of the PV array in order to reduce the current ripple. Due to the presence of the impedance network inductor in series with the PV array, the QZSI can achieve continuous input current flow. Several dc-link voltage control methods are compared and the method for power quality improvement is also presented. The performance of the proposed method is verified through both simulation and experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.182.1-182.1
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• 2010

본 논문에서는 3kW 영구 자석형 동기발전기(PMSG)를 이용한 풍력 터빈 시뮬레이터 개발에 대해 기술하였다. 풍력발전 시스템은 블레이드를 포함한 회전부, 동력 전달부, 발전기, 전력변환기로 크게 나눌 수 있으며, 시뮬레이터는 유도 모터와 PMSG, 인버터-컨버터와 제어 시스템으로 이루어진다. 시뮬레이터를 운전하기 위해서는 특정 속도의 바람 모델을 적용하여 풍력 발전기의 회전부에 걸리게 되는 토크와 회전 속도 값이 요구된다. 풍력 터빈 모델로부터 계산값을 시뮬레이터에 맞게 스케일링하여 유도 모터를 구동 한다. 발전기측 컨버터는 MPPT(Maximum Power Point Tracking) 알고리즘을 통해 제어하고 계통측 인버터는 유효 전력과 무효 전력을 제어하도록 한다. PSIM과 MATLAB/SIMULINK를 이용하여 컴퓨터 시뮬레이션으로 그 결과를 증명하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.32-34
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• 2011

본 논문은 최대전력추종 태양광 충전법을 적용한 LED 동기점멸등 제어시스템 설계 및 구현을 목표로 한다. 즉, 선박의 야간 안전항해를 돕기 위한 항로표지인 등부표에 장착되는 LED 동기점멸등의 구동제어 시스템, 최대전력추종 방식의 전류제어 벅 컨버터를 적용한 배터리 충전시스템의 설계 및 구현, 그리고 그 특성파악에 대해 중점적으로 다룬다. 시스템에 적용한 태양광 모듈의 모델링 및 MATLAB 시뮬레이션을 통해 추출한 태양전지 파라미터를 충전회로 시스템에 적용하여 최대전력추종 태양광 충전시스템을 설계하였다. 따라서, 본 논문에서는 원칩 마이크로컨트롤러를 사용하여 최대전력추종(MPPT) 태양광 충전제어시스템과 GPS활용 LED 동기점멸등 구동제어시스템을 구현하여, 그 특성파악을 통한 실시스템 적용가능성을 확인하였다.