• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.488-490
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• 2003

This paprer presents the evlauation method for transmission marginal loss factors(MLFs) considering the electrical distance. Generally, MLFs are represented as the sensitivity of transmission losses, which is computed from the change of generation by the change of the load. MLFs are classified as load-focused MLFs and generator-focused MLFs. The existing evaluation method for generator focused MLFs has the limit not reflecting the characteristic of power systems since the method has been introduced the assumption which the output of a generator is supplied to all of the load buses on the power system. Therefore, to overcome the limit of evaluation method for generator-focused MLFs, we have applied the process, which it approximately can find the load buses that supplied a generator to the method. We have applied the proposed method to the simple 5-bus system because the proposed method is not analytic but the hybrid method incorporated the Kirschen and Bialek's algorithm to the existing analytic method to find the load buses supplied by a generator.

• 전기화학회지
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• 제21권4호
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• pp.68-79
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• 2018

최근 늘어나는 배터리 수요를 대처하기 위하여 배터리를 대체하거나 배터리의 구동시간을 늘리기 위한 방법으로 제시되고 있는 에너지 발전소자와 에너지 저장소자의 융합연구는 에너지 관련 기술분야에서 가장 관심받고 있는 분야중 하나이다. 본 리뷰논문에서는 물리에너지 발전소자의 최근 연구동향과 함께 에너지 발전소자와 저장소자의 융합연구 동향을 소개하고자 한다. 먼저, 물리에너지를 전기에너지로 변환하는 압전 특성과 마찰대전 특성을 이용한 에너지 발전소자 관련 연구동향을 소개한다. 또한 압전/마찰대전 에너지 발전소자와 에너지 저장소자의 융합 연구동향을 소개한다. 특히 자가충전 에너지소자의 물리에너지를 전기화학적 에너지로 변환하는 새로운 접근방법을 소개하고자 한다.

• 한국태양에너지학회 논문집
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• 제32권2호
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• pp.11-18
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• 2012

Diesel fuel is expensive because transportation to remote areas adds extra cost, and it causes air pollution by engine exhaust. Providing a feasible economical and environmental solution to diesel generators is important. A hybrid system of renewable plants and diesel generators can benefit islands or other isolated communities and increase fuel savings. Renewable energy is, however, a natural source that produces a fluctuating power output. In this paper, hybrid power system of the marado lighthouse is proposed to supply stable power in the stand-alone hybrid power system. The proposed hybrid power system consists of the diesel generator, wind turbine, photovoltaic, fuel cell, and battery bank. To decrease the carbon emissions and find the optimization, the cost analysis of hybrid system is simulated using HOMER program and the optimized hybrid power system is designed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.231-233
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• 1995

The new hybrid scheme for electric bus is presented in this paper. This system is composed of a three-phase AC induction motor, one inveter and one system controller. The motor can be acted as starter, motor itself, alternator, generator and retarder. Various functions are simulated. The design stage has been finished. And the various experimental tests are undertaken now.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.86-92
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• 2016

Upon detecting a frequency event in a power system, the stepwise inertial control (SIC) of a wind turbine generator (WTG) instantly increases the power output for a preset period so as to arrest the frequency drop. Afterwards, SIC rapidly reduces the WTG output to avert over-deceleration (OD). However, such a rapid output reduction may act as a power deficit in the power system, and thereby cause a second frequency dip. In this paper, a hybrid reference function for the stable SIC of a doubly-fed induction generator is proposed to prevent OD while improving the frequency nadir (FN). To achieve this objective, a reference function is separately defined prior to and after the FN. In order to improve the FN when an event is detected, the reference is instantly increased by a constant and then maintained until the FN. This constant is determined by considering the power margin and available kinetic energy. To prevent OD, the reference decays with the rotor speed after the FN. The performance of the proposed scheme was validated under various wind speed conditions and wind power penetration levels using an EMTP-RV simulator. The results clearly demonstrate that the scheme successfully prevents OD while improving the FN at different wind conditions and wind power penetration levels. Furthermore, the scheme is adaptive to the size of a frequency event.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.272-278
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• 2009

The characteristics of hybrid type absorption chiller are studied numerically to use a waste hot water effectively. In the case of the full load, the concentration and temperature of LiBr solution are increase about $11^{\circ}C$, 1.3% respectively at the single effect generator by hot water. As a result, the heat of the high temperature generator are decrease, so the energy can be saved. As the partial load decreased the consumption ratio of fuels are decreased and the reduction ratio of fuels are increased. The variation of COP with the inlet temperature of hot water is higher than that of the flow rate of hot water. The effect of mean temperature difference with solution and hot water of the generator are higher that of flow rate of hot water, it can effect on COP which is sensitive to heat of generator.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.476-483
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• 2008

This paper is aimed at presenting techniques of hybrid differential evolution for solving various kinds of Economic Dispatch(ED) problems such as those including prohibited zones, emission dispatch, multiple fuels, and multiple areas. The results obtained for typical problems are compared with those obtained by other techniques such as Particle Swarm Optimization(PSO) and Classical Evolutionary Programming(CEP) techniques. The comparison of the results proves that hybrid differential evolution is quite favorable for solving ED problems with no restrictions on the shapes of the input-output functions of the generator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1174-1175
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• 2008

A operation scheme to regulate the active power output of the hybrid system consisted of a doubly fed induction generator(DFIG) and a fuel-cell are presented. The power output of the wind turbine fluctuates as the wind speed varies and the slip power between the rotor circuit and power converter varies as the rotor speed change. A fuel cell system can be individually operated and adjusted output power. In this paper, a fuel-cell is performed to regulate the active output power in comparison with the active power output of a DFIG. Based on PSCAD/EMTDC power system tools, we simulated a DFIG and a fuel cell and investigated about dynamics of the output power in hybrid system.

• 유공압시스템학회논문집
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• 제6권4호
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• pp.1-8
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• 2009

Nowadays with the high fuel prices, the demands for energy saving and green emission of construction machinery have highly been increased without sacrifice of working performance, safety and reliability. The aim of this paper is to propose a new energy saving hybrid excavator system using an electro-hydraulic actuator driven by an electric motor/generator for the regeneration of potential energy. A 5 ton class excavator is analyzed, developed with the boom for the evaluation of the designed system. The hardware implementation is also presented in this paper. A control strategy for the hybrid excavator is proposed to operate the machine with a highest efficiency. The energy saving ability of the proposed excavator is clearly verified through simulation and experimental results in comparison with a conventional hydraulic excavator.

• 전기학회논문지P
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• 제63권4호
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• pp.277-282
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• 2014

Hybrid transformer means the distribution transformer, one of multi-function transformer equipped with the enhancement function of harmonics and unbalance. In other words, since existing transformer are equipped simply with transformation function only, a separated electric facility should be additionally installed in order to reduce the mutual harmonics and unbalance. Meanwhile, since hybrid transformer can perform the reduction of harmonics and unbalance as well as transformation function simultaneously through zigzag winding, it doesn't need any additional electric facility. This study addressed the issue of developing and testing the performance of a generator that would reduce the harmonics supplied to the grid when grid-connected with the output of a photovoltaic inverter for photovoltaic generation system.