• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.199-201
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• 2003

Because of Korean power system characteristics and increasing power demand, the need of 765kV transmission line is growing gradually. Now a days, KEPCO's 765kV transmission line has been tested and stands for commercial operation. During the first stage, 765kV transmission line will be operated with two voltage grades of 765kV and 345kV, which results the unbalance of power system. So unbalanced current such as zero sequence current flows in the transmission line. In this paper, we describes the simulation study of 765/345kV parallel transmission line by using EMTDC program.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.682-687
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• 2000

In this paper, the simulation methods using transmission lines are studied and realized, which are necessary in design and analysis of hydraulic control systems. The basic idea of this method is that system components are separated by transmission line element for simulation. The PI-controller can keep inductance level as low as desired. It can also handle nonlinearities and discontinuities without flag signal when restarting integration. Parallel hydraulic circuits are simulated using parallel processing algorithm. To shoe that using variable timestep size in each subsystem, simulation time can be reduced. Performance of the simulation results is compared with that of Runge Kutta method.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.387-392
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• 2014

In this paper, a size-reduced Wilkinson balun with wide harmonic-suppressed band is presented. An accurate analysis of the parallel coupled line with an open stub (PCL-OS) is carried out. The PCL-OS structure shows excellent low pass filter and harmonic-suppression characteristics, which is useful for designing a low pass filter unit cell (LUC) with a reduced size. The designed Wilkinson balun at a 2.45 GHz center frequency not only shows an excellent harmonic suppression including the 5th harmonics up to 14 GHz over 15 dB, but it also has an area reduced to 48% of the conventional one.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.726-732
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• 2014

A current flowing through a distribution conductor produces induced voltage, which is harmful to a telecommunication line. Previous research on induced voltage has been focused on single-circuit lines in the distribution system. However, the double-circuit lines, referred to as parallel distribution lines, are widely used in distribution systems because they have significant economic and environmental advantages over single-circuit lines. Therefore, a study on the induced voltage in double-circuit lines is needed. This paper presents a method of calculating the induced voltage in a parallel distribution system using four-terminal parameters and vector analysis. The calculation method is verified by the Electromagnetic Transient Program (EMTP) simulation.

• ETRI Journal
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• v.44 no.2
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• pp.260-273
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• 2022

This study presents a novel multilayer structure of parallel coupled-line bandpass filtercentered at 2.42 GHz with a fractional bandwidth value of approximately 19.4%. The designed filter can suppress harmonics with an appropriate frequency response by incorporating different techniques based on the multilayer technique. A combination of different techniques such as radial microstrip stubs and defected ground structure (DGS) and defected microstrip structure techniques are employed to suppress harmonics up to 5f₀. These techniques are used in two layers to suppress up to 5f₀. In addition, in this study, the effects of different parameters, such as the width of slot-line DGS, the angle of diagonal line slots in the upper layer, and the air gap between the two layers on the filter performance, are investigated. To verify the correct circuit operation, the designed filter is implemented and tested. The measurement results of the proposed filter are compared with the simulation results.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.77-81
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• 2004

In this paper a novel line interactive UPS (Uninterruptible Power Supply) using the two 4-leg VSCs and AC line reactor is proposed. The 4-leg Voltage Source Converter(VSC) can use the DC link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by $15\%$ in comparison to that of the conventional line-interactive UPS system. One VSC is in parallel with the AC line reactor of the power source side, and the other is in series with the load. The parallel 4-leg voltage source inverter controls three-phase line voltage independently in order to control the line reactor current indirectly. It eliminates the neutral line current and the active ripple power of the source side using the pqr theory so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series 4-leg voltage source inverter compensates the line voltage and allows the load voltage to be balanced and harmonic-free. Both of parallel and series 4-leg voltage source inverters always act as independently controllable voltage sources, so that three-phase output voltage shows a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through computer simulation results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.4
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• pp.163-170
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• 2005

This paper deals with an improved fault location algorithm with compensation ground capacitance through distributed parameter for a long parallel T/L. For the purpose of fault locating algorithm non-influenced by source impedance and fault resistance, the loop method was used in the system modeling analysis. This algorithm uses a positive and negative sequence of the fault current for high accuracy of fault locating calculation. Power system model of 160km and 300km long parallel T/L was simulated using EMTP software. To evaluate of the proposed algorithm, we used the several different cases 64 sampled data per cycle. The test results show that the proposed algorithm was minimized the error factor and speed of fault location estimation.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1956-1958
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• 2002

This paper reviews the calculation of induced voltage to a communication line from Power Transmission Line. Power lines, both overhead and underground, often run parallel to weak current lines, such as telecommunication, signal or data transmission systems or protection circuits. The coexistence of both systems in parallel over long lengths is accompanied by the possible induction of significant longitudinal voltage in the weak current line. In order to evaluate a precise induced voltage, this paper indicated problem about coefficient and numerical formula and present some induced voltage production technology standard application.

• Journal of Advanced Navigation Technology
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• v.23 no.4
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• pp.309-315
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• 2019

This paper proposes an implementation of unequal power divider with 1:3 and 1:4 splitting ratio in multi-section structure using CPW and offset coupled transmission line. The power divider consists of a multi-section transmission line and a circuit with parallel capacitors and resistors. A multi-section transmission line was implemented by decomposing a ${\lambda}/4$ single transmission line terminated by an arbitrary impedance and converging it with a multi-section transmission line shorter than $90^{\circ}$ electrical length, and RC parallel circuits were connected between transmission lines to obtain reflection coefficient of output port and isolation characteristics between the output port. In this way, it was confirmed that the transmission lines at the unequal power divider designed at 2 GHz were shorter than ${\lambda}/4$ and implemented at least 27% less than the conventional ones, and that the broadband characteristics could be obtained.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.3
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• pp.37-42
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• 2022

A high-performance wideband transition from microstrip to waveguide is proposed. This transition is designed by consideration of gradual field transformation and optimal impedance matching between microstrip line and fin-line. Clear design guidelines of proposed transition using fin-line taper with offset DSPSL (double-sided parallel stripline) are provided to determine the transition shape and the transition length. The fabricated transition exhibits less than 0.67 dB insertion loss per transition for frequencies from 85 to 108 GHz, and less than 1 dB insertion loss from 83 to over 110 GHz. Proposed transition is expected compact radar and various applications.