• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.161-169
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• 2006

Load representation has a significant impact on power system analysis and control results. In this paper, composite load models are developed based on on-line measurement data from a practical power system. Three types of static-dynamic load models are derived: general ZIP-induction motor model, Exponential-induction motor model and Z-induction motor model. For the dynamic induction motor model, two different third-order induction motor models are studied. The performances in modeling real and reactive power behaviors by composite load models are compared with other dynamic load models in terms of relative mismatch error. In addition, numerical consideration of ill-conditioned parameters is addressed based on trajectory sensitivity. Numerical studies indicate that the developed composite load models can accurately capture the dynamic behaviors of loads during disturbance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1193-1203
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• 2016

This paper proposes a droop control scheme to compensate the unbalanced line-to-line voltage of unbalanced 3-phase load which is coupled with two inverter-based distributed generations through unequal impedance lines. Unbalanced line-to-line load voltages occur due to using single-phase loads, which brings about bad effects on the coupled inverters and the distributed generations. In order to compensate the unbalanced line-to-line voltages, a positive sequence voltage control was used for sharing the active and reactive power and a negative sequence control was used for reducing the negative sequence voltage. The feasibility of the proposed scheme was first verified by computer simulations, and then experiments with a hardware set-up built in the lab. The experimental results were compared with the simulation results to confirm the feasibility of the proposed scheme.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.754-755
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• 2008

This paper presents a method for reducing the Total Harmonic Distortion(THD) of line-line back_EMF of the IPMSM with distributed winding under the no-load condition. Firstly, the specific harmonic components of line-line back EMF are reduced considering with winding factor. Secondly, THD of line-line back EMF is minimized according to change of pole angle using by Space harmonic Analysis. Finally, the optimal design for minimizing the THD is conducted using response surface methodology with finite element analysis. The validity of the design method dealt with in this paper is demonstrated by comparison between the THD of optimal model and initial model.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2E
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• pp.53-58
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• 1998

In this paper, we study the response of several anisotropic systems to buried transient line loads. The problem is mathematically formulated based on the equations of motion in the constitutive relations. The load is in form of a normal stress acting with arbitrary axis on the plane of monoclinic symmetry. Plane wave equation is coupled with vertical shear wave, longitudinal wave and horizontal shear wave. We first considered the equation of motion in reference coordinate system, where the line load is coincident with symmetry axis of the orthotrioic material. Then the equation of motion is transformed with respect to general coordiante system with azimuthal angle by using transformation tensor. The load is first described as a body force in the equations of the motion for the infinite media and then it is mathematically characterized. Subsequently the results for semi-infinite spaces is also obtained by using superposition of the infinite medium solution together with a scattered solution from the free surface. Consequently explicit solutions for the displacements are obtained by using Cargniard-DeHoop contour. Numerical results which are drawn from concrete examples of orthotropic material belonging to monoclinic symmetry are demonstrated.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.947-953
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• 2010

The KTX-Sancheon has been commercially operating on the high-speed line since March. 2. In order to verify the performance of high-speed train and core equipments such as current collection system, sophisticated tests and evaluating procedures should have been considering. In this paper, the load cell with a built-in strain-gauge which developed to improve measuring method of contact force between the pantograph and catenary system is introduced. The static test results of the load cell shows that its design is very suitable and applicable for the dynamic test and on-line test. After the test and evaluation of load cell's dynamic calibration with pantograph, we will be applied to test interaction characteristics between the pantograph and catenary system on the high-speed line.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.780-784
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• 1998

A novel active input unbalance voltage compensator with harmonic current compensating capability is proposed and the operating principle of the proposed system is presented in the 3-phase power system. The proposed system performs both the voltage regulation of the load and the compensation of the harmonic currents generated due to nonlinear load such as diode rectifier. The system to compensate unbalanced voltage and hramonic currents is composed of a 3-phase voltage source inverter, LC filter, series transformer and passive devices at the load side of the line. The compensating voltage to regulate the load voltage and to remove the harmonic current components is transmitted to the line by the series transformer. The validity of the line by the series transformer. The validity of the proposed system is proved by the results of computer simulation.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.387-397
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• 2018

In this paper, a general closed-form solution for evaluating the dynamic behavior of a Timoshenko beam on elastic foundation under a moving harmonic line load is formulated in the frequency-wavenumber domain and in a moving coordinate system. It is found that the characteristic equation is quartic with real coefficients only, and its poles can be presented explicitly. This enables the substitution of these poles into Cauchy's residue theorem, leading to the general closed-form solution. The solution can be reduced to seven existing closed-form solutions to different sub-problems and a new closed-form solution to the subproblem of a Timoshenko beam on an elastic foundation subjected to a moving quasi-static line load. Two examples are included to verify the solution.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.115-117
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• 2002

In general, it is supposed that load characteristics of high and low voltage distribution line are always coincidence. But in practical distribution system, voltage variation characteristics of high and low voltage distribution line are not same. Then in this paper, we proposes a voltage regulation method considering load variation characteristics of high and low voltage distribution line in distribution system.

• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.27-29
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• 2004

This paper presents improved teaching and learning Gill for easily analysis tool of load flow of power system. This GUI includes not only contingency analysis function, but also calculating power loss from transmission line flow. The Gill is friendly for study for power system operation and control because picture provide a better visualizing of relationships between input parameters and effect than a tabula type result. This Gill enables topology and the output data of load flow for line outages to be shown on same picture page. Users can input the system data for power flow on the the picture and can easily see the the result diagram of bus voltage, bus power, line flow. It is also observe the effects of different types of variation of tap, shunt capacitor, loads level, line outages. Proposed Gill has been studied on the Ward-Hale 6-Bus system.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.685-688
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• 2002

This paper deals with new scheme of remote load control management system with communication from RCU to controller using power line Power line communication is useful for economical data link but various problems and limitations are caused in using power lines for communications channel. A power line is not so good in the commercial electrical power, and its load noise and high frequency noise are so much. To decrease these noise, we used the FSK(Frequency Shift Keying) modulation method. The experimental results show that the proposed system in this paper is compatible with the conventional system with low cost and the feasibility is very high for new or remodeling plant.