• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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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.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.55-57
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• 2007

A Power control and Distribution Unit (PCDU) plays roles of protection of battery against overcharge by active control of solar array generated power, distribution of unregulated electrical power via controlled outlets to bus and instrument units, distribution of regulated electrical power to selected bus and instrument units, and provision of status monitoring and telecommand interface allowing the system and ground operate the power system, evaluate its performance and initiate appropriate countermeasures in case of abnormal conditions. In this work, we perform the preliminary design of a PCDU for the small Low Earth Orbit (LEO) Satellite applications. The main constitutes of the PCDU are the battery interface module, solar array regulators with maximum power point tracking (MPPT) technology, heater power distribution modules, internal converter modules for regulated bus voltage generation, power distribution modules of unregulated and regulated primary bus, and instrument power distribution modules.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.74-76
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• 2007

In this paper a maximum power point tracking(MPPT) techniques for power of PV(photovoltaic) systems are presented using boost converter for a connected single phase inverter. On the basic principle of power generation for the PV module, algorithms for maximum power point tracking are described by utilizing a boost converter to adjust the output voltage of the PV module. Based on output power of a boost converter, single phase inverter uses predicted current control to control four IGBT's switch in full bridge. Furthermore a low cost control system for solar energy conversion using the DSP is developed, based on boost converter to adjust the output voltage of the PV module. The effectiveness of the proposed inverter system is confirmed experimentally and by means of simulation. Finally, experimental results confirm the superior performance of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1256-1258
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• 2003

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuate on the variations of insolation, temperature and loads. To obtain maximum power from solar cell, photovoltaic system cell power system usually requires maximum power point tracking controller. This paper propose Maximum power point tracking method using zero slope of differential value of maximum power. The power compare method traces to maximum power point rapidly but oscillate on the maximum power point largely, when quantity insolation variation is big. The power compare method is traces to maximum power point slowly but oscillate maximum point on the maximum power point smally, when quantity insolation variation is small. To solve two problem of the power compare method, designed zero slope of differential value of maximum power.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.228-229
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• 2007

현재까지 계통연계형 태양광 시스템의 최대전력추종(MPPT)방법에 대한 많은 연구가 진행되고 있다. 그 중 대표적인 최대 전력 추종 방법에는 일정전압 제어방식, P&O(Perturbation and Observation)제어방식, IncCond(Incremental Condutance) 제어 방식이 있다. 이 중 일정전압 제어방식은 일사량, 온도 등을 고려해 특정한 값의 태양전지 출력전압을 고정시키도록 하여, 최대전력점 근처에서 동작하도록 제어하는 방식이다. 이 방식은 태양전지 입력 전류 센서가 필요없고, 저일사량 조건에서 다른 기법에 비해 우수한 효율 특성을 나타내고 있다. 하지만, 온도 및 일사 조건에 따라 변하는 최대전력전압지점을 추종하지 못해 다양한 조건에서 최대전력추종효율이 떨어지는 단점이 있다. 이에 본 논문에서는 다양한 일사 조건 및 온도 조건에 대응하는 최대 출력전압을 실시간으로 산출하여, 이를 통해 최대전력추종제어를 하는 방법을 제안하고자 한다. 제안된 기법은 다양한 일사조건 및 온도변화에 대해 능동적으로 대응하여 우수한 추종효율 특성을 나타내고, 또한 입력 DC 전류 센서를 제거하고, 내부 연산이 간단함으로써 경제적인 면에서 유리하다. 본 논문에서 제안된 최대전력 추종기법의 타당성을 검증하기 위해서 PSIM 시뮬레이션을 통해 그 타당성을 검증 하였다.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1131-1137
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• 2018

In this paper, the authors suggest a new control algorithm for a three-phase four-wire photovoltaic (PV) inverter with imbalance load compensation function using conventional proportional-integral (PI) controllers. The maximum power of PV panel is calculated by the MPPT control loop. The reference varying signals of current controllers are transformed to two different rotating frames where they become constant signals. Then simple PI controllers are applied to achieve zero steady-state error of the controllers. The proposed control algorithm are modeled and simulated with imbalance load configuration to verify its performance. The simulation results show that the maximum PV power is transferred to the grid and the imbalance power is compensated successfully by the proposed control algorithm. The inverter has a fast response (~4 cycles) during the transient period. The proposed control algorithm can be effectively utilized to the three-phase four-wire inverter with imbalance load compensation function.

• 전력전자학회논문지
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• 제17권5호
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• pp.416-422
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• 2012

This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1377-1379
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• 2005

독립형 태양광 발전시스템은 태양전지, 배터리, 충 방전 제어기, 컨버터, 부하로 나눌 수 있다. 태양광 발전은 비선형 전압전류 특성을 가지고 있기 때문에 발전효율을 최대한 높이기 위해 최대전력추종제어(MPPT)를 하게된다. 또한 부하가 여러 개일 경우에는 다양한 출력이 요구되는데, 이를 위해 강압 및 승압이 가능한 컨버터가 필요하게 된다. 그러나 다중부하에는 다수의 컨버터와 각각의 컨버터를 제어하기 위한 제어기가 필요하게 되므로 cost가 증가요인이 된다. 따라서 본 논문에서는 승 강압에 의한 다중출력을 갖는 병렬구조의 DC-DC컨버터를 제안하고자 한다. 제안된 컨버터는 입력전압을 승 강압하여 두 개의 출력전압을 갖는다. 강압동작은 일반적인 buck형 컨버터에 커패시터를 추가하여 구성하였고, 승압을 위해서는 리플율이 적은 Coupling inductor를 이용하고 커패시터를 추가하여 두 개의 컨버터를 병렬로 구성하였다. 컨버터의 병렬제어를 위해 제어기를 설계하고 이를 시뮬레이션 하였다.

• 전력전자학회논문지
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• 제26권5호
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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.