• 설비공학논문집
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• 제17권9호
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• pp.824-829
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• 2005

MHR(Metal Hydride Refrigerator) powered by MGT exhaust gas is investigated to find out the optimum conditions corresponding to MGT operating powers. There are many factors to affect cooling capacity of MHR. In this study, the effect of switching time, flow rate of brine on cooling temperature and capacity is investigated. The present results show (1) hydrogen reaction is saturated with 25 min switching time at 25 kW MGT power, (2) cooling power shows maximum phenomenon with increasing switching time, (3) optimum switching times are 20 minutes for 15kW MGT power and 15 minutes for 20, 25kW MGT power, (4) according to increasing brine flow rate, cooling capacity shows decrease at 15 kW MGT power and changes little at above 20 kW MGT power.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.926-928
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• 1998

A fast optimization algorithm has been evolved from a simple two stage optimal power flow(OPF) algorithm for constrained power economic dispatch. In the proposed algorithm, we consider various constraints such as power balance, generation capacity, transmission line capacity, transmission losses, security equality, and security inequality constraints. The proposed algorithm consists of four stages. At the first stage, we solve the aggregated problem that is the crude classical economic dispatch problem without considering transmission losses. An initial solution is obtained by the aggregation concept in which the solution satisfies the power balance equations and generation capacity constraints. Then, after load flow analysis, the transmission losses of an initial generation setting are matched by the slack bus generator that produces power with the cheapest cost. At the second stage we consider transmission losses. Formulation of the second stage becomes classical economic dispatch problem involving the transmission losses, which are distributed to all generators. Once a feasible solution is obtained from the second stage, transmission capacity and other violations are checked and corrected locally and quickly at the third stage. The fourth stage fine tunes the solution of the third stage to reach a real minimum. The proposed approach speeds up the coupled LP based OPF method to an average gain of 53.13 for IEEE 30, 57, and 118 bus systems and EPRI Scenario systems A through D testings.

• 한국정보기술학회 영문논문지
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• 제10권2호
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• pp.91-101
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• 2020

Recently, the demand for high penetration of variable renewable energy (VRE) penetration in a power system is increased. In consequence, distribution systems including microgrids confront the increased installation of VRE-based distributed generation. Despite of the high demand of VRE-based distributed generation in a distribution system, the installation of photovoltaic (PV) system in a distribution system has been restricted by various problems. In other words, the hosting capacity for high VRE penetration in a distribution system is limited. This paper analyzes the improvements of hosting capacity VRE penetration of stand-alone microgrid (SAMG) with energy storage system (ESS) by considering virtual-slack (VS) control based on power sensitivity. With the pre-defined power sensitivity, the ESS operates as virtual slack in the SAMG by controlling its bus voltage and phase angle indirectly. Therefore, the ESS enables the increase of VRE penetration in the SAMG. The proposed VS control is realized by analyzing the ESS as a virtual slack in power flow analysis based on power sensitivity. Then its validity is demonstrated with the case study on the SAMG in South Korea with practical data.

• 동력기계공학회지
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• 제17권6호
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• pp.102-107
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• 2013

In this paper, the performance analysis for evaporation capacity, total work and efficiency of the ocean thermal energy conversion(OTEC) power system using mixed refrigerant(R32,R152a) is conducted to find the effect of hot wasted water on OTEC power system. The system in this study is applied with two stage turbine, regenerator, cooler and separator on Organic Rankine Cycle. The commercial program HYSYS is used for the performance analysis. The main results were summarized as follows : The efficiency of the OTEC power cycle has a largely effect on the evaporation capacity and total work. As increasing temperature of heat source water, evaporator's capacity is decreased but total work increase. Otherwise, using hot wasted water bring effects not only increasing system efficiency but also declining evaporator's capacity. Thus With a thorough grasp of these effect, it is necessary to find way to use hot wasted water emitted by power plant and so on.

• 한국농공학회논문집
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• 제52권6호
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• pp.1-7
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• 2010

This study was carried out to investigate the effect of hydro power factors (e.g., irrigation area, watershed area, active storage, gross head) on annual generation capacity and operation ratio for agricultural reservoirs in Chungbuk Province with active storage of over 1 million $m^3$. The annual generation capacity and operation ratio were estimated using HOMWRS (Hydrological Operation Model for Water Resources System) from last 10-year daily hydrological data. The correlation coefficients between annual generation capacity and the hydro power factors except gross head were high (over 0.87), but the correlation coefficients between operational rate and the factors were low (below 0.28). The optimum multiple regression equations of the annual generation capacity were expressed as the functions of watershed area, active storage, and gross head. Also, the simple regression equation of annual generation capacity was expressed as a function of watershed area. The average relative root-mean-square-error (RRMSE) between observed and estimated values by the optimum multiple regression equations was smaller than that by the simple regression equation, suggesting that the former has more accuracy than the latter.

• KEPCO Journal on Electric Power and Energy
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• 제5권4호
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• pp.311-321
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• 2019

정부의 재생e 3020 이행계획 및 제 8차 전력수급 기본계획과 함께 국내 분산 전원 연계 사업이 활발하게 진행되고 있다. 특히 2016년 10월 시행된 1 MW이하의 분산 전원 접속 보장 제도의 시행 이후, 배전 계통의 분산 전원 연계 신청이 급증함에 따라 송배전 설비부족으로 분산 전원 접속 지연이 일어나는 문제와, 이로 인해 국내 분산 전원의 70 %가 연계되어 있는 배전 계통의 신증설 투자비가 증가하는 문제가 이슈로 부각되고 있다. 현재 배전 계통의 분산 전원 수용력(hosting capacity) 확보 방법은 물리적인 배전 설비 추가 확충 이외에는 대안이 없는 것이 현실인데, 이러한 방식은 아래와 같은 어려움이 따른다. 첫째, 분산 전원의 대다수를 차지하는 태양광은 일조량이 풍부하고 지가가 저렴한 야외, 산악지역에 보급되므로 배전선로 경과지 확보가 점점 어려워지고 있다. 이로 인해 지중 구간이 증가하여 공사비가 증가하며, 태양광 야외 지역 위치로 공사 거리, 기간이 증가하게 된다. 둘째, 지자체의 공사 인허가 비협조 사례가 증가하여 이로 인해 공사가 지연되어 민원이 야기된다. 셋째, 배전선로 공사 자체에 1년 이상의 공사기간이 소요되므로 분산 전원을 적기에 접속시킬 수가 없으며, 넷째, 접속 신청은 지속 증가하므로 이에 따라 배전 설비 확충 비용 또한 지속 증가 할 수 밖에 없다. 이렇게 물리적 설비확충으로 발생하는 문제에 대응하여 접속 대기를 최소화하면서도 공사(투자비)를 최소화 할 수 있는 방안은 설비이용률을 극대화하는 것이며, 본 연구는 이러한 고민에서 시작되었다. 그러므로 본 논문에서는 현재 배전 계통의 분산 전원 연계 현황, 태양광 최대 출력 실적, 최소 부하, 선로 특성의 분석을 통해 배전선로의 분산 전원 상시연계용량 기준을 상향하기 위한 타당성을 검토하였으며, 배전선로의 분산 전원 상시연계용량 기준을 위한 상향(안)을 제시하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.189-192
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• 2003

Electrical power in satellite system should persistently satisfy specified power requirement even though that happen the failure of solar array string or battery cell during the mission operation. In this study, the solar array and battery of GEO Communication Satellite with 3kW capacity are designed, and energy balance analysis according to power operation mode are performed to meet specified power capacity at the transfer orbit

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.49-51
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• 2001

Recently, according to a rapid increase of the power demand, the KEPCO's 154kV lines are continuously expanded and become to the more complex loop system. As a result of increase of the fault capacity and the unbalance of power load flow, the circuit breaker have been exceeding the capacity limit of those in the loop power system. To solve this problem, APRS application will be necessary more and more.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1238-1240
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• 1998

For economic operating of distribution system, utility has to minimize the loss in distribution line by controlling reactive power and power factor. This paper presents calculation of reactive power in distribution line, estimation of the condenser capacity according to distance, and computation of optimal location and proper condenser capacity.

• 한국태양에너지학회 논문집
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• 제39권4호
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• pp.79-91
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• 2019

The capacity credit (CC) is a key metric for mid- to long-term power system capacity planning. The purpose of this study is to estimate the CCs of domestic wind turbines. Based on hourly capacity factor (CF) data during the seven years from 2011 to 2017, the new so-called probabilistic CF scheme is introduced to effectively reflect the variability of CFs on CC estimation. The CCs are then estimated through the CF-based method and the ELCC (Effective Load Carrying Capability) method reflecting the probabilistic CF scheme, and the results are compared. The results show that the CC value 0.019 for domestic wind turbines proposed in the $8^{th}$ Basic Plan for Electricity Supply and Demand corresponds to the CC with a confidence level slightly lower than 95%.