• Research Article

    MPPT Strategy to Improve Photovoltaic Power Generation Efficiency in Partial Shadows

    부분 음영에서의 태양광 발전 효율을 높이기 위한 MPPT 전략

    Heo Cheol-Young, Kim Yong-Rae, Lee Young-Kwoun, Lee Dong-Yun, Choy Ick, Choi Ju-Yeop

    허철영, 김용래, 이영권, 이동윤, 최 익, 최주엽

    In order to increase the power generation efficiency of the photovoltaic system, a new algorithm that can follow the maximum power point ... + READ MORE
    In order to increase the power generation efficiency of the photovoltaic system, a new algorithm that can follow the maximum power point of the photovoltaic power generation system having nonlinear output characteristics is proposed. Conventional maximum power point tracking (MPPT) algorithms such as Perturbation and Observation (P&O) and InCond (Increment and Conductance) schemes can not find the global maximum power point at a plurality of pole points in the unmatched state of unbalanced PV modules. However, even if the global maximum power point is found at a plurality of pole points, the global maximum power that can not be the real maximum power by the photovoltaic generation system. In order to solve this problem, a few PV companies propose installing several small PV inverters instead of if big one. However, since this will require additional costs, we herein propose a Multi-MPPT system using individual 3-point MPPT to track true MPPT at a plurality of pole points in the unmatched state of unbalanced PV modules. - COLLAPSE
    April 2019
  • Research Article

    A Study on Prediction and Adjustment of Disputes Amount of Power Generated by the PV System by the Peripheral Structure Shadow

    주변 구조물의 일조방해로 발생한 음영에 의한 태양광 발전 시스템 발전량 예측 및 분쟁 조정(안)에 대한 연구

    Oh Min-Seok, Kim Gi-Cheol

    오민석, 김기철

    The first case of the Central Environmental Dispute Mediation Committee, which recently decided to repay the builder for damaging the solar power ... + READ MORE
    The first case of the Central Environmental Dispute Mediation Committee, which recently decided to repay the builder for damaging the solar power plant due to the obstruction of the sunshine of new buildings, came out. Even if the Respondent complies with the provisions of the Building Act, the decision of the Complainant can be considered to have been made in light of the fact that the applicant's power plant has suffered from sunlight damage. However, since the extent of the damage may differ depending on the weather, the decision is reserved, and there is room for additional disputes on a regular basis because the loss of power generation to be continuously generated is not reflected in the future. Therefore, in this study, we try to find the direction of dispute adjustment by summarizing the issues related to the generation of power generation due to the influence of shading through the analysis of the case of dispute related to sunlight related to the PV system. - COLLAPSE
    April 2019
  • Research Article

    An Experimental Study on Thermal and Electrical Performance of an Air-type PVT Collector

    실험에 의한 공기식 PVT 컬렉터의 열 ‧ 전기 성능에 관한 연구

    Kim Sang-Myung, Kim Jin-Hee, Kim Jun-Tae

    김상명, 김진희, 김준태

    PVT (Photovoltaic/thermal) system is technology that combines PV and solar thermal collector to produce and use both solar heat and electricity ... + READ MORE
    PVT (Photovoltaic/thermal) system is technology that combines PV and solar thermal collector to produce and use both solar heat and electricity. PVT has the advantage that the energy production per unit area is higher than any single use of PV or solar thermal energy systems because it can produce and use heat and electricity simultaneously. Air-type PVT collectors use air as the heat transfer medium, and the air flow rate and flow pattern are important factors affecting the performance of the PVT collector. In this study, a new air-type PVT collector with improved thermal performance was designed and manufactured. And then thermal and electrical performance and characteristics of air-type PVT collector were analyzed through experiments. For the thermal performance analysis of the PVT collector, the experiment was conducted under the test conditions of ISO 9806:2017 and the electrical performance was analyzed under the same conditions. As a result, the thermal efficiency increased to 26~45% as the inlet flow rate of PVT collector increased from 60~200 m3/h. Also, it was confirmed that the air-type PVT collector prevents the PV surface temperature rise according to the operating conditions. - COLLAPSE
    April 2019
  • Research Article

    Analysis of Power Generation Characteristics of a Photovoltaic System in Korea

    태양광발전시스템 국내 지역별 발전특성 분석

    Lee Hyun-Seung, Kim Beob-Jeon, Shin U-Cheul

    이현승, 김법전, 신우철

    In this study, reflecting long-term climate characteristics, we analyzed electricity generation and generation characteristics of 3kWp PV system, which was semi-integrated with ... + READ MORE
    In this study, reflecting long-term climate characteristics, we analyzed electricity generation and generation characteristics of 3kWp PV system, which was semi-integrated with air duct behind. Using PVsyst as a simulation analysis tool, we inputted "National reference standard weather data" of 16 regions as a typical climatic data. The result is summarized as follows: First, the national average annual electricity generation was 1,312 kWh/kWp (StDev, σ = 71). It was most abundant in Mokpo with 1,434 kWh/kWp, which was average 21% greater than the lowest with 1,165 kWh/kWp in Seoul and 1,197 kWh/kWp in Jeju. National average daily generating time based on STC was 3.6 hours (σ=0.43), and that of Mokpo and Seoul was 3.9 and 3.2 hours respectively. Second, Jeju showed the great difference of annual monthly generation by month (annual average = 99.7 kWh/kWp, σ = 25.5), while Jinju showed the smallest difference (annual average = 115.5 kWh/kWp, σ = 10.6). Generation in Jeju was at the largest in April with 132.2 kWh/kWp, which was 2.3 times greater than the lowest 55.2 kWh/kWp in January. However, generation in Jinju was at the largest in March with 129.3 kWh/kWp, which was only 1.3 times greater than the lowest 101.1 kWh/kWp in June. Third, the annual average PR was the highest in Incheon with 85.8% and the lowest in Jeju with 83.2%. PR of Mokpo was 84.3%, which was lower than that of national average. - COLLAPSE
    April 2019
  • Research Article

    Alternative Selection Method for Energy Efficiency Improvement of Old Detached House

    노후 단독주택의 난방에너지 효율 개선을 위한 대안 선정 방법에 관한 연구

    Hwang Seok-Ho

    황석호

    More than 76% of the detached houses in Korea are over 20 years old. These old detached houses have poor energy efficiency ... + READ MORE
    More than 76% of the detached houses in Korea are over 20 years old. These old detached houses have poor energy efficiency. According to the 2017 Housing Census (Statistics Korea), more than 50% of low-income families live in detached houses. Therefore, the improvement of energy efficiency in old detached houses is needed from the viewpoint of energy welfare. The general method of building energy modelling for the verification of energy efficiency is based on the construction year data of “Building Design Criteria for Energy Saving” due to the cost and time involved in collecting the thermal performance data of buildings. There is poor accuracy with the deterioration of long-term aging of building materials. Also, the selection of alternatives for energy performance improvement is based on the items to be applied, not a performance improvement goal. It is difficult to calculate energy performance that reflects variations in various parameters with dynamic energy simulations. In this study, the influence of long-term aging is used to accurately predict the energy performance of old detached houses. The building energy modelling method is called ENERGY#, which is a static analysis method based on ISO13790. Energy performance is evaluated by a combination of input variables including building orientation, insulation of walls and roof, thermal performance of windows and window/wall ratio, and infiltration rate. Finally, this study provides a way to determine alternatives that meet energy performance improvement goals. - COLLAPSE
    April 2019
  • Research Article

    Case Study for Energy Conservation Measures of Hospital Buildings Using the Analysis of Energy Consumption Structure

    의료시설 에너지절약 운영방법 도출을 위한 사례분석을 통한 에너지 영향요소 분석

    Lee Sangmoon, Cho Jinkyun

    이상문, 조진균

    Because the hospital building operates 24 hours a day, 365 days a year for treatment and restoration of patients, it has a ... + READ MORE
    Because the hospital building operates 24 hours a day, 365 days a year for treatment and restoration of patients, it has a different pattern of energy use than that of ordinary buildings. Hospitals contribute to energy consumption and have a negative environmental impact. This study aims to find how meaningful energy performance, reflecting good energy management and ECMs, can be operated for hospital buildings, a category encompassing complex buildings with different systems and large differences between them. In this study, we proposed the energy diagnosis & evaluation method and energy management process to verify energy saving through operation data based on system & facility characteristics, operation pattern and energy consumption characteristics of hospital building. Energy consumption structures were surveyed throughout 4 reference hospital in Seoul, Korea. Findings confirm that different hospital departments have hugely different energy-demand profiles. Energy efficiency and energy saving potentials are presented. The energy performance analysis can be applied to a wide range of problems in energy-system operation. - COLLAPSE
    April 2019
  • Research Article

    Evaluation of UM-LDAPS Prediction Model for Daily Ahead Forecast of Solar Power Generation

    태양광 발전 예보를 위한 UM-LDAPS 예보 모형 성능평가

    Kim Chang Ki, Kim Hyun-Goo, Kang Yong-Heack, Yun Chang-Yeol

    김창기, 김현구, 강용혁, 윤창열

    Daily ahead forecast is necessary for the electricity balance between load and supply due to the variability renewable energy. Numerical weather prediction ... + READ MORE
    Daily ahead forecast is necessary for the electricity balance between load and supply due to the variability renewable energy. Numerical weather prediction is usually employed to produce the solar irradiance as well as electric power forecast for more than 12 hours forecast horizon. UM-LDAPS model is the numerical weather prediction operated by Korea Meteorological Administration and it generates the 36 hours forecast of hourly total irradiance 4 times a day. This study attempts to evaluate the model performance against the in situ measurements at 37 ground stations from January to May, 2013. Relative mean bias error, mean absolute error and root mean square error of hourly total irradiance are averaged over all ground stations as being 8.2%, 21.2% and 29.6%, respectively. The behavior of mean bias error appears to be different; positively largest in Chupoongnyeong station but negatively largest in Daegu station. The distinct contrast might be attributed to the limitation of microphysics parameterization for thick and thin clouds in the model. - COLLAPSE
    April 2019
  • Research Article

    Optimal Design of Notch Filter in Photovoltaic Inverter

    태양광 인버터의 노치 필터 최적 설계

    Kim Yong-Rae, Heo Cheol-Young, Lee Young-Kwoun, Choy Ick, Choi Ju-Yeop

    김용래, 허철영, 이영권, 최 익, 최주엽

    When Photovoltaic inverter is connected to grid and used as PVPCS (Photovoltaic Power Conditioning System), 120 Hz AC ripple occurs at the ... + READ MORE
    When Photovoltaic inverter is connected to grid and used as PVPCS (Photovoltaic Power Conditioning System), 120 Hz AC ripple occurs at the dc-link capacitor voltage. This AC ripple reduces the efficiency of PVPCS and shortens the lifetime of the capacitor. In this paper, we design a notch filter to remove AC ripple. As a result, the AC voltage ripple was removed from the dc link and the THD of the PVPCS output current with the notch filter was lowered. This notch filter is determined by the damping coefficient, the bandwidth coefficient, and the switching frequency. Among these, the switching frequency determines the switching loss and the size of the LC filter, and the PVPCS with the high switching frequency has a greater efficiency loss due to the switching loss than the efficiency improvement by the notch filter. Therefore, it is important to set the optimum switching frequency in the PVPCS with the notch filter applied. In this paper, THD and switching loss of PVPCS output current with notch filter are calculated through simulation, and cost function to calculate optimum switching frequency through data is proposed. - COLLAPSE
    April 2019