• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 A
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• pp.673-675
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• 2005

• Journal of Electrical Engineering and Technology
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• 제6권6호
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• pp.742-749
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• 2011

Power transmission lines are one of the most important components of electric power system. Failures in the operation of power transmission lines can result in serious power system problems. Hence, fault diagnosis (transient or permanent) in power transmission lines is very important to ensure the reliable operation of the power system. A hidden Markov model (HMM), a powerful pattern recognizer, classifies events in a probabilistic manner based on fault signal waveform and characteristics. This paper presents application of HMM to classify faults in overhead power transmission lines. The algorithm uses voltage samples of one-fourth cycle from the inception of the fault. The simulation performed in EMTPWorks and MATLAB environments validates the fast response of the classifier, which provides fast and accurate protection scheme for power transmission lines.

• 유공압시스템학회논문집
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• 제6권3호
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• pp.10-15
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• 2009

The major system of an agricultural power-shift tractor is the transmission, using power-shift. Because the transmission performance depends on the hydraulic control system, the most important aspect of the optimization is the design of the hydraulic control system. This study was conducted to improve a pressure modulation characteristics of the power-shift transmission hydraulic system. It has been tried to replace an existing pressure modulation method with a digital control by using HSSV(High Speed Solenoid Valve). The performance of the PWM control system in power-shift hydraulic transmission has been evaluated by means of experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.171-173
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• 2002

This paper presents a power system decomposition technique for digital simulation of large power system. To decompose power system, distributed transmission line model is used. But this model can be used only for long transmission lines. In this paper, capacitor compensation method is proposed to use distributed transmission line model for short transmission line. And case study shows proposed method can be used for effective power system decompositon in digital simulation of large power system.

• 에너지공학
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• 제15권4호
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• pp.256-276
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• 2006

경쟁적 전력시장에서, 송전혼잡은 지역적 시장지배력의 핵심 요인들 중 하나이다. 재무적 송전권을 구매한 시장 참여자는 그들이 지불한 혼잡 세를 돌려받음으로써 재무적 보호를 받을 수 있다. 하지만 많은 연구에서, 이러한 송전권이 오히려 시장지배력을 강화시킴을 보였다. 따라서 본 논문은 새로운 개념의 송전권인 Contingent Transmission Rights을 이용해 지역적 시장지배력을 완화시키는 것이 목적이다. 본 논문은 각 모선의 한계가격 (Locational Marginal Pricing LMP)을 기반으로 한 모선별 가격제도(Nodal Pricing)와 최적조류계산(Optimal Power Flow)를 이용해 사례연구를 수행하였다.

• Journal of Power Electronics
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• 제19권1호
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• pp.211-219
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• 2019

In magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the introduction of additional intermediate coils is an effective means of improving transmission characteristics, including output power and transmission efficiency, when the transmission distance is increased. However, the position of intermediate coils in practice influences system performance significantly. In this research, a three-coil MCR WPT system is adopted as an exemplification for determining how the spatial position of coils affects transmission characteristics. With use of the fundamental harmonic analysis method, an equivalent circuit model of the system is built to reveal the relationship between the output power, the transmission efficiency, and the spatial scales, including the axial, lateral, and angular misalignments of the intermediate and receiving coils. Three cases of transmission characteristics versus different spatial scales are evaluated. Results indicate that the system can achieve relatively stable transmission characteristics with deliberate adjustments in the position of the intermediate and receiving coils. A prototype of the three-coil MCR WPT system is built and analyzed, and the experimental results are consistent with those of the theoretical analysis.

• 전기학회논문지
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• 제56권2호
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• pp.268-276
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• 2007

Transmission congestion is one of the key factors to local market power in competitive electricity markets. Financial transmission rights provide the financial protection to their holders by paying back the congestion rent. A variety researches have shown that the existing trading mechanisms on transmission right can exacerbate market power. This paper proposes an alternative methodology in mitigating the local market power using the Contingent Transmission Rights on the locational marginal pricing scheme. The proposed methodology was demonstrated with the Optimal Power Flow.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권7호
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• pp.406-411
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• 2000

This paper presents the results of performance confirmation tests for domestic 20 [Ton] transmission suspension insulators which will be widely utilized in transmission lines. The new test methods such as power arc test, steep-front-of-wave flashover voltage test, and etc. which have been only utilized for the distribution insulators were applied in transmission suspension insulators. The properties of metal and cement used in the 20 [Ton] transmission insulators were also evaluated by the various analysis techniques. Based on the results, we evaluated the performance of the transmission suspension insulators.

• 전기학회논문지
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• 제66권11호
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• pp.1554-1560
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• 2017

Prepare a lose of 765kV transmission route in power system operation condition, there are some Special Protection Scheme(SPS)s in Korean power system. These SPS can make some preselected generators are tripped to avoid generator overspeed. Because of many of the new large power plants are installed to existing power generation sites due to the siting problem, the number of generator tripped by SPS should be increased. But that can be a cause of system frequency change under the Under Frequency Relay(UFR) 1st pickup level 59.0Hz. Therefore generation constraint should be considered until new transmission lines are installed. In this paper, we propose the ESS application for generation constraint mitigation by frequency damping control of ESS. To analysis an effect of ESS application, we use PSS/E dynamic simulation tool, CBEST model and controller model. The proposed ESS application is applied to the empirical Korean power system.

• 전기학회논문지P
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• 제67권2호
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• pp.112-118
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• 2018

In recent years, decentralized power have been increasing due to environmental problems, liberalization of electricity markets and technological developments. These changes have led to the evolution of power generation, transmission, and distribution into discrete sectors and the division of integrated power systems. Therefore, studies are underway to efficiently supply power and reduce losses to each sector's demand. This is a major concern for system planners and operators, as it accounts for a relatively high proportion of total power, with a transmission and distribution loss of 4-6%. Therefore, this paper analyzes the status of loss management based on the current transmission and distribution loss rate of each country and transmission loss management cases of each national power company, and proposes a loss rate prediction algorithm according to the long-term transmission system plan. The proposed algorithm predicts the demand-based long-term evolution and the loss rate of the grid to which the transmission plan is applied.