• ETRI Journal
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• 제31권1호
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• pp.42-50
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• 2009

A new method for simulating voltage and current distributions in transmission lines is described. It gives the time domain solution of the terminal voltage and current as well as their line distributions. This is achieved by treating voltage and current distributions as distributed state variables (DSVs) and turning the transmission line equation into an ordinary differential equation. Thus the transmission line is treated like other lumped dynamic components, such as capacitors. Using backward differentiation formulae for time discretization, the DSV transmission line component is converted to a simple time domain companion model, from which its local truncation error can be derived. As the voltage and current distributions get more complicated with time, a new piecewise exponential with controllable accuracy is invented. A segmentation algorithm is also devised so that the line is dynamically bisected to guarantee that the total piecewise exponential error is a small fraction of the local truncation error. Using this approach, the user can see the line voltage and current at any point and time freely without explicitly segmenting the line before starting the simulation.

• 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.

• 설비공학논문집
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• 제6권4호
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• pp.344-353
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• 1994

This study numerically analyzed the dynamic characteristics of the frequency response on the pneumatic transmission line with load impedances. The pressure transfer function is represented by the distributed parameter line model. To validate the mathematical approximations of Bessel function ratios, the results of frequency response in a blocked line were compared with those obtained by the Infinite-product, Brown's and Square-root approximations. Special emphasis was given to the frequency response characteristics on the pneumatic transmission line with load impedances. Computations were carried out for the wide range of parameters in terms of load capacitance ratio and load resistance ratio. The present results indicated that the theoretical model is capable of accurately predicting the frequency response characteristics for any configuration of a fluid transmission line.

• 대한기계학회논문집
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• 제18권11호
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• pp.3075-3083
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• 1994

The applications of the electrical transmission line theory to the pressure propagation characteristics in the volume loaded fluid transmission line with step and impulse input wave is demonstrated in this paper. The method is based on the premise that the time response is the inverse Fourier transform of frequency spectrum of the wave which spectrum is a product of frequency spectrum of input pressure wave and system transfer function. The frequency response and transient response of step and impulse input wave in the volume loaded fluid transmission line is analysed by the Laplace transform and inverse Laplace transform with FFT numerical algorithm. The numerical solution of the distributed friction model is compared with the average friction model and the infinite product model. And the result is showed that FFT method may have major advantages for the simulation of fluid circuitary.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.283-287
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• 2003

A new method to miniaturize ${\lambda}/4$ transmission line of power divider is proposed. The method utilizes simple combination of the shorted coupled-line pair instead of the transmission line with very high impedance and shunt lumped capacitors. The length of ${\lambda}/4$ transmission line of power divider is about 16% over the conventional power divider at 1 GHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2553-2555
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• 1999

The paper contains design formulas and an execution algorithm for calculation of distributed parameters as well as wave and impedance parameters of a uniform transmission line using data of the line input impedance measurements by the OPEN-SHORT method. In difference from published before works on the OPEN-SHORT method application for line parameters determination, in which the lines with small losses are considered /1-3/, the obtained formulas allow to calculate parameters of transmission lines with arbitrary losses. It opens new possibilities of the OPEN-SHORT method utilization for development and application of the probe - type lossy dielectric media parameters meters based on transmission lines, including probe-type moisture material meters.

• 대한전기학회논문지
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• 제39권4호
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• pp.333-340
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• 1990

분산 송전송실정보에 의한 전력시스템의 경제운용=The transmission loss information produced in a line may be shared by both end buses connected to the line. Then, the loss may be seen as if it is discretely produced at both buses. Likewise, all transmission losses can be considered as if they are discretely produced at every bus distributed. The bus transmission loss equation can be defined, in which the loss information about connected lines are contained. This formulation can greatly enhance the computational efficiency for the economic control of both real powers and voltages. It requires solutions of two linear matrix equations, one for the calculation of incremental transmission losses and the other for the determination of voltage levels to be controlled. The Proposed approach is demonstrated through three sample systems and it is found that the solutions can be obtained after three iterations regardless of system sizes. This implies that only one-step search would be required for the solution if real informations would be available. Results are compared with those of optimal power flows.

• 한국광학회지
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• 제14권4호
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• pp.434-442
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• 2003

전파정수가 불규칙하게 존재하는 선로를 설정하고, 선로 상의 파동함수의 해가 국재성을 나타내는 원인과 그 조건에 대하여 확률함수를 이용하여 해석하였다. 랜덤한 매질로는 특성 임피던스가 불규칙하게 변동하는 전송선로를 설정하고, 이 선로 상에서의 전압파나 전류파의 국재현상에 대하여 살펴보았다. 수치해석을 실시한 결과, 랜덤 선로 중에 국재하는 해가 존재하는 것이 확인되었으며, 전류원을 삽입하여 선로를 강제 여진시킨 경우에도 선로 상에 전압파가 국재하는 것을 알 수 있었다. 선로 전체에 손실을 설정한 경우에 대한 해석 결과에서는 국재가 존재하는 위치의 파가 가장 큰 영향을 받는다는 사실에서, 광의 국재는 파동이 반사를 반복하는 것에 의해 나타난다는 것을 알 수 있었다.

• Journal of Power Electronics
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• 제19권3호
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• pp.803-814
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• 2019

This paper proposes a three-phase current balancing strategy in a power transmission system employing distributed static series compensators (DSSCs). With the proposed variable quadrature voltage injection method, the DSSC emulates either an inductive or a capacitive impedance into the transmission line, and the magnitudes of the phase currents are balanced. Hence, the phase imbalances in the power transmission system are significantly reduced. As a result, the power transfer capability of the transmission lines can be improved. The operational principle of the DSSCs, the hardware structure and the control algorithm are described in detail. Finally, the theoretical analyses and the proposed strategy are experimentally verified through a scaled down transmission system with DSSC prototypes.

• 한국인터넷방송통신학회논문지
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• 제14권2호
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• pp.147-152
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• 2014

2단으로 구성된 DFB 레이저의 정적 및 동적 작용을 분석하기 위하여 종방향 모드 전송선로 이론 (L-MTLT)을 이용하였다. 활성영역을 갖는 DFB 구조의 특성 임피던스와 등가 전파상수를 L-MTLT에 기초하여 유도하였다. 2단으로 구성된 DFB 레이저가 전송선로 망으로 유사화 되었으며, 각 단은 그에 대응하는 등가 요소들로 등가화된 전송선로 블록으로 나타내었다. 등가 전송선로 망에 기초한 DFB 레이저의 종방향 공진 조건 (resonance condition)이 레이트 방정식 (rate equation)을 재구성하기 위하여 사용되었으며, 이를 이용하여 활성여역을 갖는 2단 DFB 레이저의 정적 및 동적 작용을 자세하게 분석하였다.