• Proceedings of the KIPE Conference
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• 2016.07a
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• pp.451-452
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• 2016

최근 풍력 및 태양광 발전과 같은 분산전원 시스템의 설비가 증가함에 따라 전력 생산자가 늘어나고 있으며 발전량이 불규칙적인 신재생에너지 자원을 전력 수요에 따라 효율적으로 운용하고 관리하기 위한 에너지 저장장치(Energy storage system : ESS)의 필요성이 증가하고 있다. 최근에는 기존의 중앙집중 방식의 전력 시스템이 가지는 여러 문제를 해결하기 위해 여러 분산 발전 요소들과 에너지 저장장치, 부하 및 계통을 상호 연결한 마이크로그리드의 개념이 제안되고 있다. 마이크로그리드 내에서 분산전원과 계통에 ESS가 연계 되면 전력수급 상황에 따라 잉여전력이 발생할 때 전력을 저장할 수 있으며 전력수요가 클 때 저장된 전력을 부하에 공급하여 전력설비를 보다 안정적이고 효율적으로 운용할 수 있다. 본 논문에서는 풍력발전 시스템, 양방향 충/방전이 가능한 ESS, 부하 및 계통이 연계된 마이크로그리드를 대상으로 이를 효율적으로 운용하고 계통전력 사용을 최소화 할 수 있는 독립형 마이크로그리드의 자율적 제어기법에 대한 연구를 수행한다. 전력수급 상황에 따라 각 요소들의 운전 모드를 결정하는 기법이 제시되고 각 동작 모드에서의 분석 및 시뮬레이션에 의한 검증을 통하여 본 제어기법의 효용성을 입증한다.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.163-164
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• 2017

본 논문에서는 KMSL(Korea Microgravity Science Laboratory) 큐브 위성에 대해 설명하고 전력시스템 설계 연구 방법을 제시한다. 1~3리터 사이즈인 초소형 인공위성(큐브위성)의 전력시스템은 태양 전지 패널로부터 큐브 위성의 부하장치 운용을 위한 전력을 공급받고, 남은 잉여 전력은 배터리에 저장하여 식(eclipse) 구간 동안 전력이 공급될 수 있도록 전력계가 구성된다. 본 논문에서는 조선대학교 KMSL팀의 큐브 위성에 대한 전력시스템을 설계하기 위해서 위성 궤도 및 자세에 따른 생산 전력, 소비 전력을 인공위성의 자세 및 궤도에 따라 분석하고, 부하 장치의 전원 및 소모전력을 통해 전력 및 에너지 마진(margin)이 충분하도록 전력계시스템의 구성품 용량을 설계하였다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.155-155
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• 2017

최근 애플망고 스마트 농가에 에너지 사용량이 증가됨에 따라 에너지 절감을 위한 대책들과 화석연료를 대체하는 다양한 신재생에너지 도입에 대한 요구들이 늘고있다. 본 연구에서는 애플망고 스마트 농가에 여러 에너지원들을 혼합하여 사용할 수 있도록 실증시험 모델을 구축하고 운영함으로써 그 효용성을 검토하고자 하였다. 우선 애플망고 특성을 고려한 비닐온실의 최대 냉난방부하량과 에너지모델을 분석하여 신재생 에너지원들의 혼합 및 기존 공조설비와의 연계를 계산하였다. 애플망고 시험 농지로는 재배에 적합한 제주도 서귀포를 선정하였으며, 기존의 경유 난방기를 사용하는 비교시험 하우스, 기존의 경유와 태양광, 지하 공기 히트펌프 난방기를 혼합하여 사용하는 실증시험 하우스, 경유와 지하공기 히트펌프 난방기를 사용하는 대조시험 하우스를 10~11월 두 달간 운영하여 그 결과들을 평가하였다. 온실 내외부에 온도, 습도, CO2를 측정할 수 있는 6점의 센서부들을 설치하였고, 적산 전력계와 유량계를 설치하여 데이터를 수집하였으며, 모든 시험 데이터는 모바일 원격으로 제어 및 모니터링이 가능하도록 구성하였다. 시험 결과, 각 하우스들에서 수확한 과실의 수량과 품질은 유사하게 평가되었지만, 실증시험 하우스의 난방비가 비교시험 하우스보다 절감되었다. 하지만 실증시험 하우스의 경우 높은 시설유지비로 인해 이를 고려한 사용료는 비교시험 하우스보다 더 비싸게 평가되었다. 본 연구를 통해 생산된 잉여전력을 매전할 때 이로 인한 이용비는 비교시험 하우스보다 더 경제적임을 확인할 수 있었다. 또한 기존의 경유와 지하공기 히트펌프 난방기를 혼합한 대조시험 하우스의 난방비용이 경제성에서 더 유리함을 알 수 있었다. 따라서 본 연구를 통해 애플망고 스마트 농가에 적합한 에너지-믹스 모델을 구축할 수 있었으며, 다양한 신재생에너지들의 효용성들을 검토할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.360-369
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• 2008

The solar cells should be operated at the maximum power point because its output characteristics were greatly fluctuated on the variation of insolation, temperature and load. It is necessary to install an inverter among electric power converts by means of the output power of solar cell is DC. The inverter is operated supply a sinusoidal current and voltage to the load and the interactive utility line. In this paper, the proposes a photovoltaic system is designed with a step up chopper and single phase PWM voltage source inverter. Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper is operated in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature for solar cell has typical dropping character. The single phase PWM voltage source inverter is consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be develop continuously by connecting with the source of electric power for ordinary using. It can be cause the efect of saving electric power, from 10 to 20%. The single phase PWM voltage source inverter operates in situation, that its output voltage is in same phase with the utility voltage. The inverter are supplies an ac power with high factor and low level of harmonics to the load and the utility power system.

• Journal of Advanced Navigation Technology
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• v.20 no.4
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• pp.265-274
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• 2016

In this study, the system was composed of the booster chopper and the power converter, which is a pulse width modulation (PWM) voltage inverter using a hybrid power generation system solar cell energy and wind force, Furthermore, in order to compensate the PWM voltage type inverter was linked with the general commercial power source, and through a normal operation of energy storage system (ESS), the system operated the LED Taxi Light by Wavelength according to Meteorological Changes at the airport in an efficient manner. The performance of the system was compared with the solar cell characteristics specification. In addition, for phase synchronization with the PWM voltage type inverter, the grid voltage was detected so as to operate the grid voltage and inverter output in the same phase and to connect the surplus electric power with the system. Finally, by developing a control circuit at the same time from which an excellent dynamic characteristics can be obtained through applying to the airport runway taxi light, it was concluded that a variety of taxi light can be pursued.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.99-120
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• 2017

In SS branch of Korea District Heating Corporation, Combined Heat & Power power plant with 99MW capacity and 98Gcal / h capacity is operated as a district electricity business. In this region, it is difficult to operate the generator due to the problem of surplus heat treatment between June and September due to the economic recession and the decrease in demand, so it is urgent to develop an economical energy new business model. In this study, we will develop an optimized operation model by introducing a renewable energy hybrid system based on actual operation data of this site. In particular, among renewable energy sources, fuel cell (Fuel Cell) power generation which can generate heat and electricity at the same time with limited location constraints, photovoltaic power generation which is representative renewable energy, ESS (Energy Storage System). HOMER (Hybrid Optimization of Multiple Energy Resources) program was used to select the optimal model. As a result of the economic analysis, 99MW CHP combined cycle power generation is the most economical in terms of net present cost (NPC), but 99MW CHP in terms of carbon emission trading and renewable energy certificate And 5MW fuel cells, and 521kW of solar power to supply electricity and heat than the supply of electricity and heat by 99MW CHP cogeneration power, it was shown that it is economically up to 247.5 billion won. we confirmed the results of the improvement of the zone electricity business condition by introducing the fuel cell and the renewable energy hybrid system as the optimization process model.

• Korean Journal of Agricultural and Forest Meteorology
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• v.23 no.3
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• pp.141-148
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• 2021

Agrivoltaic systems, also called solar sharing, stated from an idea that utilizes sunlight above the light saturation point of crops for power generation using solar panels. It is expected that agrivoltaic systems can realize climate smart agriculture by reducing evapotranspiration and methane emission due to the reduction of incident solar radiation and the consequent surface cooling effect and bring additional income to farms through solar power generation. In this study, to evaluate that agrivoltaic systems are suitable for realization of climate smart agriculture, we conducted agro-environmental observations (i.e., downward/upward shortwave/longwave radiations, air temperature, relative humidity, water temperature, soil temperature, and wind speed) in a rice paddy under an agrivoltaic system and compared with the environment outside the system using automated meteorological observing systems (AMOS). During the observation period, the spatially averaged incoming solar radiation under the agrivoltaic system was about 70% of that in the open paddy field, and clear differences in the soil and water temperatures between the paddy field under the agrivoltaic system and the open paddy field were confirmed, although the air temperatures were similar. It is required in the near future to confirm whether such environmental differences lead to a reduction in water consumption and greenhouse gas emissions by flux measurements.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• Journal of the Korean Society of Radiology
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• v.4 no.3
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• pp.31-37
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• 2010

In this paper, a photovoltaic system is designed with PWM(Pulse Width Modulation) voltage source inverter. Proposed synchronous signal and control signal was processed by 56F8323 microprocessor for stable modulation. The PWM voltage source inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power, from 10 to 20[%]. The PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In addition, I connected extra power to the system through operation the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and PWM voltage inverter can be synchronized. In the system of this research showed good results after being controlled in order to provide stable power to the load and the system through maintaining and low output power of harmonics.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.200.2-200.2
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• 2010

This study was carried out in order to reduce the amount of underground water which is used in the water curtain system for retaining heat. To proceed to the research, two plastic green houses of water curtain system were installed. One was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50cm in diameter filled with subsurface water. Storing surplus solar energy in the water filled in PVC duct was the method used to this house. Another was installed with FCU in the middle of the house, and was fitted a circulation motor in water tank for heat storage which was operated from 10 a.m. to 4 p.m. in order to interchange heat with FCU. The latter was installed with four FCUs which has a capacity of 8000kcal per hour. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of more than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. It happened that to prevent the water from freezing, mixing antifreezing liquid in the flowing water of FCU or changing the operating method of FCU was a suitable measure. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Therefore when supposed that the amount of water used in the house is 150~200ton for stable operation of FCU, using the system mentioned in the above research happened to be appropriate of reducing the amount of subsurface water from 80% to 100% when maintaining the interior of internal small tunnel's temperature for keeping warm air of 5 degrees celsius at the extreme temperature of minus 5 degrees celsius.