• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권12호
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• pp.527-531
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• 2005

Because of increasing demand for safety of the power transformer, the seismic qualification process in accordance with the standard of IEEE Std 693-1997 is essentially required by customer. Dynamic analysis method and static analysis method were used to qualify the seismic withstanding of the power transformer at high seismic level. Maximum stress was detected at the connection between the main structure and appendages, and maximum displacement was detected at the point of appendage's end tip. Load path and substructure system can be considered as important elements to prevent over stress and over displacement.

• Journal of Power Electronics
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• 제9권6호
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• pp.919-928
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• 2009

Microgrids (MGs) are typically comprised of distributed generators (DGs) including renewable energy sources (RESs), storage devices and controllable loads, which can operate in either interconnected or isolated mode from the main distribution grid. This paper introduces a novel dynamic programming (DP) approach to MG optimization which takes into consideration the coordination of energy supply in terms of heat and electricity. The DP method has been applied successfully to several cases in power system operations. In this paper, a special emphasis is placed on the uncontrollability of RESs, the constraints of DGs, and the application of demand response (DR) programs such as directed load control (DLC), interruptible/curtaillable (I/C) service, and/or demand-side bidding (DSB) in the deregulated market. Finally, in order to illustrate the optimization results, this approach is applied to a couple of examples of MGs in a certain configuration. The results also show the maximum profit that can be achieved.

• 에너지공학
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• 제16권1호
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• pp.22-31
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• 2007

본 논문에서는 전력수급기본계획에 열병합발전설비의 최적용량을 반영할 수 있는 방법론을 개발하였으며 이에 따른 효과를 분석하였다. 이를 위해 열병합발전의 계획발전원가를 새로이 산정하여 심사곡선법(Screening Curve Method : SCM)을 이용한 정태적 최적 전원을 구성하였다. 이때, 열병합발전은 전기와 열을 생산하는 것이 가장 중요한 특징이므로 이를 고려할 수 있도록 열병합발전의 전기용량과 열용량을 모두 고려할 수 있는 계획발전원가를 도출하였다. 또한, 심사곡선법을 적용시키기 위한 부하지속곡선의 경우도 열병합발전의 특징을 고려하여 전기 및 열 부하지속곡선을 구성하여 적용하였다. 이때, 현재 수립된 전력 수급기본계획을 최대한 수정하지 않는 범위 내에서 열병합발전설비를 반영하도록 하였다. 열병합발전 건설계획을 반영한 계획안의 타당성을 증명하기 위해서 열병합발전 건설계획을 반영한 계획안과 전력수급기본계획을 비교 하였다. 즉, 발전량 기대치를 산출하여 발전원별 연료소비량 및 환경에 미치는 영향을 도출함으로써 열병합발전의 반영에 대한 효율성을 입증하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.194-194
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• 2010

The variable demand on the energy market, as well as the limited energy storage capabilities, requires a great flexibility in operating hydraulic turbines. But, present in Korea, the absence of testing laboratories and technical criteria for the performance test of small hydropower degrades the efficiency of the domestic hydropower machines, A performance guarantees for hydro turbines shall be contain, as a minimum, guarantees covering power, discharge and specific hydraulic energy, efficiency, maximum momentary overspeed and maximum momentary pressure and/or maximum steady-state runaway speed, as well as guarantees related to cavitation. Performance test are conducted by the test standard. Test codes based on extensive research data are written under the leadership of an IEC. Performance evaluation is carry out several test(performance test, cavitation test and runaway test). The paper presents the international turbine test laboratory and performance test standard.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.755-765
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• 2015

A thermostatically controlled load (TCL) can be one of the most appropriate resources for demand response (DR) in a smart grid environment. DR capability can be effectively implemented in a TCL with various intelligent control methods. However, because traditional on-off control is still a commonly used method in a TCL, it is useful to develop a method for adding DR capability to the TCL with an existing on-off controller. As a specific realization of supervisory control for implementing DR capability in the TCL, two methods are proposed - a method involving the changing of a set point and a method involving the paralleling of an identified system without delay. The proposed methods are analyzed through the simulations with an electric heater for different power consumption levels in the on-state. Considerable cost benefit can be achieved with the proposed methods when compared with the case without DR. In addition, the observations suggest that a medium power consumption level, instead of the maximum power, in the on-state should be used for consistently obtaining the cost benefit without severe temperature deviation from the specified temperature range for DR.

• 한국ITS학회 논문지
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• 제11권3호
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• pp.81-91
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• 2012

최근 기후변화에 따른 위기감으로 인해 세계 각국은 화석연료의 자동차를 전기자동차로 대체하기 위한 노력을 기울이고 있다. 정부는 2020년까지 소형차의 10% 이상을 전기자동차 보급 목표로 설정하였고 '주택건설 기준 등에 관한 규정'을 개정하여 전기자동차 충전설비를 공동주택의 부대설비에 포함시키는 등 충전 인프라 구축에도 노력하고 있다. 공동주택에서 전기자동차의 충전 인프라 및 주차 공간 등의 확보는 전기자동차 보급에 있어 핵심이 되지만, 이들에 대한 합리적 용량 산정 등에 필요한 전기자동차의 수요예측 연구는 미미한 상태이다. 이를 위해 본 연구는 수도권의 공동주택 거주자(분양과 임대 구분)를 대상으로, 통계자료의 시계열분석과 선호도 결과를 이용하여 전기자동차 수요를 예측하였다. 그 결과 2020년 공동주택 거주자의 전기자동차 비율은 임대아파트의 경우 6～21%, 분양아파트는 21～39% 수준이며, 이들의 사용을 지원할 최대전력량은 1,000가구 1일 기준으로 임대아파트 4,200kwh, 분양아파트 7,800kwh로 예측되었다.

• Advances in Energy Research
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• 제7권2호
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• pp.85-100
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• 2020

Distributed energy resources (DERs) are essential for coping with growing multiple energy demands. A microgrid (MG) is a small-scale version of the power system which makes possible the integration of DERs as well as achieving maximum demand-side management utilization. Hence, this study focuses on the analysis of optimal power dispatch considering economic aspects in a multi-carrier microgrid (MCMG) with price-responsive loads. This paper proposes a novel time-based demand-side management in order to reshape the load curve, as well as preventing the excessive use of energy in peak hours. In conventional studies, energy consumption is optimized from the perspective of each infrastructure user without considering the interactions. Here, the interaction of energy system infrastructures is considered in the presence of energy storage systems (ESSs), small-scale energy resources (SSERs), and responsive loads. Simulations are performed using GAMS (General Algebraic modeling system) to model MCMG, which are connected to the electricity, natural gas, and district heat networks for supplying multiple energy demands. Results show that the simultaneous operation of various energy carriers, as well as utilization of price-responsive loads, lead to better MCMG performance and decrease operating costs for smart distribution grids. This model is examined on a typical MCMG, and the effectiveness of the proposed model is proven.

• Journal of Power Electronics
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• 제9권4호
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• pp.643-653
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• 2009

Voltage-controlled voltage source inverter (VCVSI) based distributed generation systems (DGS) using renewable energy sources (RES) is becoming increasingly popular as grid support systems in both remote isolated grids as well as end of rural distribution lines. In VCVSI based DGS for load voltage stabilization, the power angle between the VCVSI output voltage and the grid is an important design parameter because it affects not only the power flow and the power factor of the grid but also the capacity of the grid, the sizing of the decoupling inductor and the VCVSI. In this paper, the steady state modeling and analysis in terms of power flow and power demand of the each component in the system at the different values of maximum power angle is presented. System design considerations are examined for various load and grid conditions. Experimental results conducted on a I KVA VCVSI based DGS prove the analysis and simulation results.

• 자원ㆍ환경경제연구
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• 제16권4호
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• pp.901-922
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• 2007

본 연구는 하계냉방수요가 기온관련변수의 변화에 대해 어떤 반응을 보이는가, 또 어떤 종류의 기온관련변수가 하계냉방수요에 대한 설명변수로 더 적절한가를 보기 위해 일반적인 선형모형은 물론 각기 다른 특성을 가지고 있는 지수모형과 파워모형, S곡선모형 등 비선형모형을 이용하여 2004년부터 2007년까지 최근 4년간 자료를 분석하였다. 실증분석결과 본 연구에서는 기온관련변수들 가운데 불쾌지수가 일최고기온에 비해 설명력이 우수하다는 사실과 함께 하계냉방전력수요가 전체 4개년도 중 2006년을 제외한 다른 모든 연도들에 대해 지수모형을 따라 기온관련변수의 변화에 대응하고 있는 사실을 규명하였다. 또 소득수준의 향상을 반영하는 비냉방전력수요의 꾸준한 증가와 함께 냉방전력수요도 기온관련변수에 매년 더욱 민감하게 반응하고 있는 사실도 발견하였다.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.403-411
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• 2005

At present, the Cournot model is one of the most commonly used theories to analyze the gaming situation in an oligopoly type market. However, several problems exist in the successful application of this model to the electricity market. The representative one is obtaining the inverse demand curve able to be induced from the relationship between market price and demand response. In the Cournot model, each player offers their generation quantity to obtain maximum profit, which is accomplished by reducing their quantity compared with available total capacity. As stated above, to obtain the probable Cournot equilibrium to reflect the real market situation, we have to induce the correct demand function first of all. Usually the correlation between price and demand appears over the long-term through statistical data analysis (for example, regression analysis) or by investigating consumer utility functions of several consumer groups classified as residential, industrial, and commercial. However, the elasticity has a tendency to change continuously according to the total market demand size or the level of market price. Therefore it should be updated as the trading period passes by. In this paper we propose a method for inducing and updating this price elasticity of demand function for more realistic market equilibrium.