• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.509-513
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• 2008

In this paper, we investigate how generators' ramp-rate constraints may influence their equilibrium strategy formulation. In the market model proposed in this study, the generators' ramp-rate constraints are explicitly represented. In order to fully characterize the inter-temporal nature of the ramp-rate constraints, a dynamic game model is presented. The subgame perfect Nash equilibrium is adopted as the solution of the game and the backward induction procedure for the solution of the game is designed in this paper. The inter-temporal nature of the ramp-rate constraints results in the Markov property of the game, and we have found that the Markov property of the game significantly simplifies the subgame perfect Nash equilibrium characterization. Finally, a simple electricity market numerical illustration is presented for the successful application of the approach proposed.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.45-48
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• 2003

Ramp-rate limitation is a serious obstacle for successful operation of fast charging and discharging magnet Ramp-rate limitation is hard to expect or fully investigate due to its electric and thermo-hydraulics couplings. In this paper, the simplest case of ramp-rate limitation is investigated with two-strand superconducting cable model considering transient heat transfer The simulation results are compared with the experimental results.

• 한국전기전자재료학회논문지
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• 제21권10호
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• pp.916-922
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• 2008

AC PDP with MgO protective layer coated with the optimum evaporation rate of $5{\AA}/s$ can generate more enhanced efficiency through the vacuum in-line sealing process. However, the optimized process conditions still require the optimum driving scheme on the ramp-up and ramp-down slope of the reset waveform for enhancing the efficiency. In this paper, for the in-situ vacuum sealed PDP with the optimum evaporation rate of MgO protective layer, the address delay time was investigated with various slopes of ramp waveform during a reset ramp-up and ramp-down period. In this study, the minimum statistical delay time was obtained at the ramp-up rate of $6.0 V/{\mu}s$ and the ramp-down rate of $0.7 V/{\mu}s$ of the reset waveform.

• 전기학회논문지
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• 제60권3호
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• pp.509-516
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• 2011

This paper studies a novel method to find the profit-maximizing Nash Equilibriums in allocating generation quantities with consideration of ramp-rates under competitive market environment. Each GenCo in a market participates in a game to maximize its profit through competitions and play a game with bidding strategies. In order to find the Nash equilibriums it is necessary to search the feasible combinations of GenCos' strategies which satisfy every participant's profit and no one wants various constraints. During the procedure to find Nash equilibriums, the payoff matrix can be simplified as eliminating the dominated strategies. in each time interval. Because of the ramp-rate, generator's physically or technically limits to increase or decrease outputs in its range, it can restrict the number of bidding strategies of each generator at the next stage. So in this paper, we found the Nash Equilibriums for multi-stage generation allocation game considering the ramp-rate limits of generators. In the case studies, we analyzed the generation allocation game for a 12-hour multi-stage and compared it with the results of dynamic economic dispatch. Both of the two cases were considered generator's ramp-rate effects.

• 한국도로학회논문집
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• 제10권4호
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• pp.139-150
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• 2008

본 연구는 도로연장측면에서 본선에 비해 상대적으로 연결로에서 발생하는 사고빈도가 높고, 교통사고가 증가하는 추세인 고속도로 연결로의 교통사고 예측모형의 개발에 초점을 두었다. 연결로 유형별(직결, 준직결, 루프)로 통계적으로 유의한 사고인자를 선정하고, 사고율과의 관계가 비선형 임을 분석하여 변수를 변형(Variables Transformation)하여 All possible 방식으로 예측모형을 개발하고, 통계적 진단 및 검증을 거쳐 유의성을 확인하였으며 이에 기존 개발 모형에 비해 예측력이 더욱 우수한 결과를 보였다. 개발된 사고예측모형은 보다 비용면에서 효율적이고, 안전한 트럼펫형 IC 연결로의 설계와 연결로 교통사고 원인분석에 활용될 수 있을 것으로 기대된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.37-40
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• 1996

Cable-In-Conduit Conductor(CICC) is widely accepted as an advanced superconductor configuration for large scale applications such as tokamak fusion reactors, MAGLEV (MAGnetic LEVitation), and SMES (Superconducting Magnetic Energy Storage). The stability of CICC cooled with supercritical helium can be very high if it is operated below a certain limiting current. This limiting current can be determined by Stekly type heat balance equation. The stability characteristic of CICC for AC operation is more complicated than that of DC because there are additional instability sources which are associated with local flux change. Ramp-rate limitation is a phenomenon discovered during US-DPC (United States-Demonstration Poloidal Coil) program, which showed apparent quench current degradation associated with high dB/dt. This paper describes recent experimental investigation results on the ramp-rate limitation and discusses current imbalance, induced current, current redistribution due to local quench of the strand in the cable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.569_570
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• 2009

This paper presents a methodology to find the profit maximized Nash Equilibriums of each generator(or GenCo), which considers the Ramp-rate of each generator under a competitive market environment. The ramp-rate of a generator is one of the physical or technical constraints of a generator and means the ability to increase or decrease the output instantaneously. In this paper, we found several Nash Equilibriums of the generation allocation problem through Dynamic Programming in a competitive market. Individual generators participate in a game to maximize its profit through competitions and play a game with bidding strategies of its generation quantities in a spot market.

• 대한토목학회논문집
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• 제39권2호
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• pp.361-367
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• 2019

램프미터링은 고속도로로 진입하는 차량들을 제어함으로써 고속도로 본선의 정체를 줄이는 교통운영기법으로, 국외에서는 많이 사용되고 있으며 우리나라도 외곽순환도로 7개소에서 운영중이다. 램프미터링은 본선 정체를 줄이는 장점이 있는 반면 단점도 존재하는데, 램프 출구에서 차량들이 신호를 받고 대기하기 때문에 대기행렬이 발생하고 차량이 많은 시간대는 램프 대기행렬이 인접 도로에 까지 영향을 미치게 된다. 따라서 이를 해결하기 위해 공간적으로 여유가 있는 램프는 진입 수요를 많이 제어하고 공간적으로 여유가 없는 곳은 진입 수요를 적게 제어하도록 램프미터링 알고리즘을 개선하였다. 이를 평가하기 위해 통합평가지수(Combined Index)를 사용하였고 평가 결과 형평성과 효율성을 동시에 만족하는 것으로 나타났다.

• 한국생산제조학회지
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• 제20권4호
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• pp.434-439
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• 2011

There are about 2.4million disabled in Korea, 2009. Also, Korean society entered into an aging society. Therefore disable and elderly are getting more involved in our society. This study proposes simple ramp design for wheel chair users and welding method and condition for manufacturing. In the middle of ramp, screw jack and motor are installed so that ramp can be moved left and right side. To make the ramp moves easily, ramp was fixed by installing LM guide on both sides. Ramp production for using Nd:YAG laser certain dissimilar welding in stainless steel sheet and cold reduced carbon steel. The output was fixed by 3kW, the speed was increased to 2~7m/min, Argon was used as shielding gas and the flow rate was changed to 10~30L/min. The proper welding condition is the output 3kW and welding speed 2~5m/min.

• 전기학회논문지P
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• 제63권4호
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• pp.254-259
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• 2014

In this paper, we describe construction of a wind stabilization demo-site and effects of output power control of wind turbines for suppression of ramp rate using ESS (Energy Storage System). It is difficult to control the output power of distributed generator such as wind turbine which of variation is very large. If the large capacity wind farm be interconnected into power system may cause blackout due to Power Quality. For these reasons, the international standards such as Grid-Code is limited to less than 10 [%/min] of renewable energy ramp rate. The case of Korea, government actively conducts propagating large-scale renewable energy for green growth policy, to interconnecting more renewable energy into power system is necessary for stabilization technology. For these reasons, the POSCO consortium has constructed a wind stabilization demo-site that is configured as 500 [kWh] battery energy storage systems can output up to 3 [C-Rate] and two wind turbines rated 750 [kW]. In POSCO consortium, which implements various methods stabilizing output power of wind turbine such as smoothing, section firming and ramp control, we derive the results of long-term demonstration that can be controlled to satisfy to the international standard about ramp rate [%/kW] of wind turbine output power.