• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.2
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• pp.67-72
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• 2006

Most of the load distributions in low voltage power feeder distribution systems are designed with approximately balanced and connected at the three phase four wire systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating load unbalance. Load unbalance factor is mainly affected by the impedance of load system. Unbalanced current will draw a highly unbalanced voltage. This paper presents a new calculation method for unbalance factor under the load variation at the three phase four wire system. Load unbalance factor is measured by the power quality measurement apparatus and compared with the current unbalance factor. Two methods are indicated similar results.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.58-64
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• 2004

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. Voltage unbalance is a condition in a polyphase system in which the rms values of the line-to-line voltages or the phase angles between consecutive line-to-line voltages, are not all equal. Slight voltage unbalance generates a disproportionately high current unbalance at the motor stator winding. This paper presents a scheme on operation states of a three-phase induction motor under unbalanced voltages. The three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of each phase. The voltage unbalanced factor(VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on machine's operation characteristics.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.110-115
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• 2004

Most of the loads in industrial power distribution systems are balanced and connected to three power systems. However, in the user power distribution systems, most of the loads are single & three phase and unbalanced, generating voltage unbalance. This paper presents a scheme on operation states of a three-phase induction motor under unbalanced voltages. The three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting the magnitude and phase angle of each phase. The voltage unbalanced factor(VUF) of the three-phase source voltages can then be varied to examine the different values of VUF on machine's operation characteristics.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.1
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• pp.56-60
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• 2005

In the power-line communication(PLC) systems, the power line is a wired medium. However, the power line channel has the multi-path fading characteristics like the wireless channel in the wireless communication systems because it has the signal reflection and divergence by the impedance mismatching between many branch lines and loads. So the analysis of the multi-path characteristics is very important, and it has been doing by the several measurement methods for the impulse response between the transmitter and the receiver. PN sequence method has originally been used as a wideband impulse response measurement mettled for wireless channel, but it is recently being applied to not only the wireless channel but also the wired channel like the power line channel. This method is more useful and effective for the long distance communication channel like the medium voltage power distribution line with the multi-paths[1]. In this thesis, we have measured impulse response for the medium voltage power distribution line channel by the wideband measurement method using PN sequence, analytically studied the measured data and presented the results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.11
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• pp.66-73
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• 2015

AC-based power systems, having the advantages that voltage transformation and long distance transmission are easy, have been constructed since the last 19th century. However, DC-based power system is paid attention these days because of the development of power electronic devices as well as the increase of digital loads and distributed generation. For instance, the transmission systems using High Voltage DC (HVDC) are commercially operated in the world and the researches on distribution system using Low Voltage DC (LVDC) are gradually increased. This paper analyzes voltage sag, resulted from faults, in LVDC distribution system according to the number of poles. Modeling and simulation with various conditions are conducted by using ElectroMagnetic Transients Program (EMTP). Moreover, some countermeasures to reduce voltage sag in LVDC distribution system are suggested briefly.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1183-1184
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• 2006

Using the MATLAB/SIMULINK, this paper presents dynamic simulation model for 6MW wind power generation systems with the DFIG considering distribution systems and performs the dynamic analysis of wind power systems

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.6
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• pp.325-332
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• 2003

The loss minimization is one of the most important problems to save the operational cost in distribution systems. This paper presents an efficient method for optimal feeder reconfiguration of distribution systems. Chaos search algorithm (CSA) is used to reconfigure distribution systems so that active power losses are globally minimized with turning on/off sectionalizing switches. In optimization problem, the CSA searches the global optimal solution on the basis of regularity in chaotic motions and easily escapes from local or near optimal solution. The CSA is tested on 15 buses and 32 buses distribution systems, and the results indicate that it is able to determine appropriate switching options for global optimum reconfiguration.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.761-763
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• 1997

As the power system network is enlarged and complicated gradually, the automation of power system network is essential to enhance the reliability and performance of the operation of power system. Distribution restoration is a major part of the automation. This paper proposes a new distribution restoration system to restore healthy blackout regions by the hierarchical cooperation with the substation automation systems. In proposed system, the range of restoration is extended to substations and the performance as well as the switching efficiency of restoration system is enhanced.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.119-120
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• 2013

Wind turbines as a power distribution system linked to the driving operation according to the characteristics of the distribution system can be adversely affected by a change of circumstances, depending on Distribution Systems with driving characteristics of a wind turbine can be affected. Thus according to the grid-tied wind turbines and transient suppression of the distribution lines and distribution lines outside of the accident in order to maintain stable power supply to supply reactive power efficient system is necessary to keep the voltage constant. In this paper, we substantiated in Jeju Hangwon 12 Unit Level 1MVA STATCOM system configuration, control, configure, and test results will be introduced.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.737-743
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• 2013

The small-scaled onsite generators such as photovoltaic power, wind power, biomass and fuel cell belong to decarbonization techniques. In general, these generators tend to be connected to utility systems, and they are called distributed generations (DGs) compared with conventional centralized power plants. However, DGs may impact on stabilization of utility systems, which gets utility into trouble. In order to reduce utility's burdens (e.g., investment for facilities reinforcement) and accelerate DG introduction, the advanced operation algorithms under the existing utility systems are urgently needed. This paper presents the advanced voltage regulation method in power systems since the sending voltage of voltage regulators has been played a decisive role restricting maximum installable DG capacity (MaxC_DG). For the proposed voltage regulation method, the difference from existing voltage regulation method is explained and the detailed concept is introduced in this paper. MaxC_DG estimation through case studies based on Korean model network verifies the superiority of the proposed method.