• 전기학회논문지
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• 제60권11호
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• pp.2007-2016
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• 2011

In this paper, a new algorithm for alleviating overloads in power networks by the use of line power tracing and sensitivity is proposed to perform line switching and bus separation effectively. Also, a new bus separation index based on line power tracing is presented to find the bus to be separated for relieving overloads effectively. By applying the sensitivity of the line flow with respect to the change of the line impedance, both switching-on and switching-off of the lines for alleviating overloads in power networks are performed systematically at once. The number of the considered cases for line switching and bus separation can be greatly reduced and the best combination of line switching and bus separation can be acquired efficiently by the use of the sensitivity and the bus separation index. In order to show the effects of this algorithm, it is applied to a small scale power system of IEEE 39-bus system and practical power systems of KEPCO.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1299-1301
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• 1999

This paper describes a initial screening methods for weak line selection using sensitivity matrix. The elements of sensitivity matrix for line suceptance have 1 or -1, 0. From this property of sensitivity matrix, the eigen-sensitivity for line suceptance can be computed very simply and selected weak line for small signal stability or transient stability. The proposed algorithm is applied to small signal stability of New England 39-bus system and also applied to voltage stability of New England 30-bus system too.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2005년도 추계학술대회
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• pp.30-39
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• 2005

Line capacity calculation has been used to determine optimum efficiency and safe train service for train scheduling plan and investment priority order throughout detecting bottleneck section. Because of some problems of Yamagisi and UIC methods for line capacity calculation, developing of the method of line capacity calculation and evaluation for the Korea circumstance is important. This paper deals with the integrated system of TPS(Train Performance Simulator), PES(Parameter Evaluation Simulator), LCS (Line Capacity Simulator) and sensitivity analysis for line capacity calculation model.

• 대한안전경영과학회지
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• 제7권4호
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• pp.207-217
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• 2005

Line capacity calculation has been used to determine optimum efficiency and safe train service for train scheduling plan and investment priority order throughout detecting bottleneck section. Because of some problems of Yamagisi and UIC methods for line capacity calculation, developing of the method of line capacity caculation and evaluation for the Korea circumstance is important. This paper deals with the reliability improvement on the integrated system of TPS(Train Performance Simulator), PES(Parameter Evaluation Simulator), LCS(Line Capacity Simulator) and simulation and sensitivity analysis for line capacity.

• 대한전자공학회논문지TC
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• 제43권12호
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• pp.75-82
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• 2006

본 논문에서는 개구를 갖는 접지면의 높은 특성 임피던스를 이용하여 주파수에 대한 민감도가 좋고 높은 품질 계수를 갖는 미앤더 라인 인덕터들을 설계하였다. 주파수에 대한 민감도는 자기 공진 주파수 (SRF) 대신에 해석 주파수 범위에 대한 유효 인덕턴스 변화량으로 새로 정의 되었다. 등가 집중 소자 회로는 고주파 인덕터의 특성을 설명하기 위해 전개되었다. 개구 접지면을 갖는 4 nH 미앤더 라인 인덕터는 0.45 nH/GHz의 좋은 민감도와 0.7 GHz에서 86의 Q 값을 갖는다.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1689-1696
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• 2017

In recent academic and industrial circles of the Republic of Korea, the securement of available reactive power reserve against the line faults is at issue. Thus, simulations have been performed for the securing of effective reactive power reserve (effective Q) to prepare for the line faults and improve reactive power monitoring and control methods. That is, a research has been conducted for the fast-decoupled Newton-Raphson method. In this study, a method that distinguishes source and sink regions to carry out faster provision of information in the event of line fault has been proposed. This method can perform quantification with the formula that calculates voltage variations in the line flow. The line flow and voltage changes can be easily induced by the power flow calculation performed every second in the operation system. It is expected that the proposed method will be able to contribute to securement of power system stability by securing efficient reactive power. Also, the proposed method will be able to contribute to prepare against contingencies effectively. It is not easy to prepare quickly for the situation where voltage drops rapidly due to the exhaustion of reactive power source by observing voltage information only. This paper's simulation was performed on the large scale Korean power system in steady state.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.32-41
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• 2011

This paper presents a new method of Fuzzy Particle Swarm Optimization (FPSO)-based Congestion Management (CM) by optimal rescheduling of active powers of generators. In the proposed method, generators are selected based on their sensitivity to the congested line for efficient utilization. The task of optimally rescheduling the active powers of the participating generators to reduce congestion in the transmission line is attempted by FPSO, Fitness Distance Ratio PSO (FDR-PSO), and conventional PSO. The FPSO and FDR-PSO algorithms are tested on the IEEE 30-bus and Practical Indian 75-bus systems, after which the results are compared with conventional PSO to determine the effectiveness of CM. Compared with FDR-PSO and PSO, FPSO can better perform the optimal rescheduling of generators to relieve congestion in the transmission line.

• International Journal of Aeronautical and Space Sciences
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• 제16권3호
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• pp.437-444
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• 2015

Satellite selection and exclusion techniques have been applied to the global navigation satellite system (GNSS) with the aim of achieving a balance between navigational performance and computational efficiency. Conventional approaches to satellite selection based on the best dilution of precision (DOP) are excessively computational and complicated. This paper proposes a new method that applies a geometric sensitivity index of individual GNSS satellites. The sensitivity index is derived using the inner product of the line of sight (LOS) vector of each satellite. First, the LOS vector is computed, which accounts for the geometry between the satellite and user positions. Second, the inner product of each pair of LOS vectors is calculated, which indicates the proximities of the satellites to one another. The proximity can be determined according to the sensitivity of each satellite. A post-processing test was conducted to verify the reliability of the proposed method. The proposed index and the results of a conventional approach that measures the dilution of precision (DOP) were compared. The test results demonstrate that the proposed index produces results that are within 96% of those of the conventional approach and reduces the computational burden. This index can be utilized to estimate the sensitivity of individual satellites, obtaining a navigation solution. Therefore, the proposed index applies to satellite selection and exclusion as well as to the sensitivity analyses of multiple GNSS applications.

• 대한전기학회논문지:전력기술부문A
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• 제51권4호
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• pp.183-187
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• 2002

The efficient and rational transmission tariff structure is one of the crucial factors in creation of fair and competitive electricity markets. Transmission charge can be largely categorized into the line usage charge, system reliability charge, access charge and others. Any transmission tariff should be able to reflect these cost components reasonably. This paper suggests an approach amenable to allocating the transmission reliability costs reasonably with reflection of line sensitivity and line outage rate.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 D
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• pp.1118-1120
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• 1997

This paper presents a simple method for evaluating of voltage stability using the line flow equation. Line flow equations ($P_{ij}$, $Q_{ij}$) are comprised of state variable, $V_i$, ${\delta}_i$, $V_j$ and ${\delta}_j$, and line parameter, r and x. Using the feature of polar coordinate, these becomes one equation with two variables, $V_i$ and $V_j$. Moreover, if bus j is slack or generater bus, which is specified voltage magnitude, it becomes one equation with one variable $V_i$, that is, may be formulated with the second-order equation for $V_i^2$. Therefore, multiple load flow solutions may be obtained with simple computation, and the formulated equation used for approximately evaluating of voltage stability limit considering line flow sensitivity. The proposed method was validated to 2-bus and IEEE 6-bus system.