• ETRI Journal
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• v.45 no.4
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• pp.636-649
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• 2023

Renewable energy generation cannot be consistently predicted or controlled. Therefore, it is currently not widely used in the electricity market, which requires dependable production. In this study, reliability- and variance-based controls of energy storage strategies are proposed to utilize renewable energy as a steady contributor to the electricity market. For reliability-based control, photovoltaic (PV) generation is assumed to be registered in the power generation plan. PV generation yields a reliable output using energy storage units to compensate for PV prediction errors. We also propose a runtime state-ofcharge management method for sustainable operations. With variance-based controls, changes in rapid power generation are limited through ramp rate control. This study introduces new reliability and variance indices as indicators for evaluating these strategies. The reliability index quantifies the degree to which the actual generation realizes the plan, and the variance index quantifies the degree of power change. The two strategies are verified based on simulations and experiments. The reliability index improved by 3.1 times on average over 21 days at a real power plant.

• KIEAE Journal
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• v.16 no.3
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• pp.113-119
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• 2016

Purpose: In this study, we evaluate the annual energy performance of the detached house which was designed with the aim of zero energy. Method: The experimental house which was constructed in Gonju Chungnam in 2013, is the single family detached house of light weight wood frame with $100m^2$ of heating area. Thermal transmittance of roof (by ISO 10211) and building external walls are designed as $0.10W/m^2K$ and $0.14W/m^2$ respectively and low-e coating vacuum window glazing with PVC frame was installed. Also grid connected PV system and natural-circulation solar water heater was applied and 6kWp capacity of photovoltaic module was installed in pitched roof and $5m^2$ of solar collector in vertical wall facing the south. We analyzed the 2014 annual data of the detached house in which residents were actually living, measured though web-based remote monitoring system. Result: First, as a result, total annual energy consumption and energy production (PV generation and solar hot water) are 7,919kWh and 7,689kWh respectively and the rate of energy independence is 97.1% which is almost close to the zero energy. Second, plug load and hot water of energy consumption by category showed the highest numbers each with 33% and 31%, with following space heating 24%, electric cooker 8%, lighting 3% in order. Hot water supply is relatively higher than space heating because high insulation makes it decreased.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.68-75
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• 2012

Small hydropower is one of the many types of new and renewable energy, which is planning to develop, as the country is abundant in endowed resources. In order to fully utilize small hydropower resources, there is a need for greater precision in quantifying small hydropower resources and establish an environment in which energy sources can be discovered using the small hydropower resource management system. This study has given greater precision to calculate annual electricity generation and capacity of small hydropower plants of Nakdong river system by inquiring into average annual rainfall, basin area and runoff coefficient, which is anticipated to promote small hydropower resources utilization. Small hydropower resource management system was also established by additionally providing base information on quantified small hydropower resources and analysis function and small hydropower generator status, rivers, basin, rainfall gauging station, water level gauging station etc.. Small hydropower resource management system can be used gather basic information for positive applications of small hydropower energy nationwide.

• Solar Energy
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• v.9 no.3
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• pp.81-91
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• 1989

This study represents the method to predict the flow duration curve and primary design specifications of small hydropower plant at hydropower site through analyzing the monthly rainfall data. Weibull distribution was selected to characterize the rainfall data and Thiessen method was used to calculate monthly average flowrate at site. Application of these results, primary design specifications such as design flowrate, annual average load factor and utility factor, annual average hydropower density and annual electric energy production were estimated and discussed for surveyed site located in Daigi-ri, Kangwon province. And performance characteristic model of small hydro-power plant was applied to estimate these specifications.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.218-221
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• 2010

This paper presents energy efficiency about an electrolyser which is related with the hybrid system of solar cell and fuel cell for using the system more fully. The water electrolyser is the exact reverse of a hydrogen fuel cell; it produces gaseous hydrogen and oxygen from water. Electrolyser technology may be implemented at a variety of scales wherever there is an electricity supply to provide hydrogen and/or oxygen for virtually any requirement. Also, this paper shows optimum operating point in the electrolyser for saving cost of the electrical energy with hybrid system.

• Transactions of the Korean hydrogen and new energy society
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• v.14 no.3
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• pp.268-275
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• 2003

The water-splitting process by the metal oxides using solar heat is one of the hydrogen production method. The hydrogen production process using the metal oxides (NiFe2O4/NiAl2O4,CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite) was carried out by two steps. The first step was carried out by the CH4-reduction to increase activation of metal oxides at operation temperature. And then, it was carried out the water-splitting reaction using the water at operation temperature for the second step. Hydrogen was produced in this step. The production rates of H2 were 110, 160, 72, 29, 17, $21m{\ell}/hr{\cdot}g-_{Metal\;Oxide}$ for NiFe2O4/NiAl2O4, CoFe2O4/CoAl2O4, CoMnNiFerrite, CoMnSnFerrite, CoMnZnFerrite, CoSnZnFerrite respectively in the second step. CoFe2O4/CoAl2O4 had higher H2 production rate than the other metal oxides.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.297-302
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• 2020

A coverglass pattern was designed to improve the annual electrical energy production of a building-integrated photovoltaic (BIPV) module installed in the exterior walls of buildings. The transmittance pattern was calculated using ray tracing, and the results were derived by optimizing the simulation using Taguchi's method. We obtained the optimal pattern by analyzing the conventional patterns for improving the transmittance and derived design factors by quantifying the pattern. By calculating the influence of electrical energy on each design factor, we obtained the optimal coverglass pattern that produced the maximum annual electrical energy. The annual electrical energy production improved by approximately 11.79% compared to the non-patterned coverglass.

• Advances in Energy Research
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• v.6 no.2
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• pp.131-143
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• 2019

Global Solar Radiation (GSR) is the key element for performance estimation of any Solar Power Plant (SPP). Its forecasting may help in estimation of power production from a SPP well in advance, and may also render help in optimal use of this power. Seasonal Auto-Regressive Moving Average (SARMA) and Artificial Neural Network (ANN) models are combined in order to develop a hybrid model (SARMA-ANN) conceiving the characteristics of both linear and non-linear prediction models. This developed model has been used for prediction of GSR at Gorakhpur, situated in the northern region of India. The proposed model is beneficial for the univariate forecasting. Along with this model, we have also used Auto-Regressive Moving Average (ARMA), SARMA, ANN based models for 1 - 6 day-ahead forecasting of GSR on hourly basis. It has been found that the proposed model presents least RMSE (Root Mean Square Error) and produces best forecasting results among all the models considered in the present study. As an application, the comparison between the forecasted one and the energy produced by the grid connected PV plant installed on the parking stands of the University shows the superiority of the proposed model.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.422-426
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• 2016

With the increase in installed solar energy capacity, comparison and analysis of the physical property values of solar cells are becoming increasingly important for production. Therefore, research on determining the physical characteristic values of solar cells is being actively pursued. In this study, a diode equation, which is commonly used to describe the I-V behavior and determine the electrical characteristic values of solar cells, was applied. Using this method, it is possible to determine the diode ideality factor (n) and series resistance ($R_s$) based on light I-V measurements. Thus, using a commercial screen-printed solar cell and an interdigitated back-contact solar cell, we determined the ideality factor (n) and series resistance ($R_s$) with a modified diode equation method for the light I-V curves. We also used the sun-shade method to determine the ideality factor (n) and series resistance ($R_s$) of the samples. The values determined using the two methods were similar. However, given the error in the sun-shade method, the diode equation is considered more useful than the sun-shade method for analyzing the electrical characteristics because it determines the ideality factor (n) and series resistance ($R_s$) based on the light I-V curves.

• Proceedings of the KIEE Conference
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• summer
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• pp.1495-1497
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• 2004

This paper presents an effective modeling scheme of SPE cell system for hydrogen production. As oxygen and hydrogen produced by water electrolysis using SPE are high purity, we can use oxygen in biomedical and hydrogen could be used in many ways. Recently, it is under the eye as a surplus power storage system. PSCAD/EMTDC model of SPE cell system for hydrogen production to efficiently utilize Solar cell energy which produces effectively hydrogen energy is showed in this paper. The simulated results are then verified by comparing them with the actual values obtained from the data acquisition system. Authors are sure that it is a useful method to the researchers who study SPE cell system for hydrogen production.