• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.11
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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.

• KIEE International Transactions on Power Engineering
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• v.5A no.1
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• pp.79-84
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• 2005

In many countries, the electric power industry is undergoing significant changes known as deregulation and restructuring. These alterations introduce competition in generation and retail and require open access to the transmission network. The competition of the electric power industry causes many issues to surface. Among them, unbundling of the transmission service is probably the most complicated as it is a single and integrated sector and the transmission revenue requirement must be allocated to market participants in a fair way. In these situations, it is valuable to research the methodologies to allocate transmission usage. The power tracing method offers useful information such as which generators supply a particular load or how much each generator (load) uses a particular transmission line. With this information, we can allocate required transmission revenue to market participants. Recently, several algorithms were proposed for tracing power flow but there is no dominant power tracing method. This paper proposes a power tracing method based on graph theory and complex-current distribution. For practicability, the proposed method for transmission usage allocation is applied to IEEE 30 buses and compared with the method proposed by Felix F.Wu.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.304-309
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• 1997

A method to mitigate the thermal stratification flow of a horizontal pipe line is proposed by heating external bottom of the pipe with electrical heat tracing. Unsteady two dimensional model has been used to numerically investigate an effect of the external Denting to the thermally stratified flow. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature distribution, streamline profile and Nusselt numbers of fluids and pipe walls with time are analyzed in case of externally heating condition. no numerical result of this study shows that the maximum dimensionless temperature difference between the hot and the cold sections of pipe inner wall is 0.424 at dimensionless time 1,500 ann the thermal stratification phenomena is disappeared at about dimensionless time 9,000. This result means that external heat tracing can mitigate the thermal stratification phenomena by lessening $\Delta$ $T_{ma}$ about 0.1 and shortening the dimensionless time about 132 in comparison with no external heat tracing.rnal heat tracing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.8
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• pp.1145-1153
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• 2015

The paper analyzes reactive power flow characteristic in power system by reactive power tracing. In addition, virtual buses are inserted in the algorithm to consider losses of transmission lines, and shunt capacitor treated as a reactive power generator. The results of simulation are analyzed by two points of view. The one is load’s point of view and another is generator’s point of view. Classic purpose of the reactive power tracing consists in the reactive power pricing. However, it is significantly used to select vulnerable area about line outage in this paper. To find the vulnerable area, reactive power tracing variations between pre-contingency and post-contingency are calculated at all load buses. In heavily load area, buses which has highest variation become the most vulnerable bus. This method is applied to the IEEE 39-bus system. It is compared with voltage variation result and VQ-margin to verify its effect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.505-508
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• 2016

In city, tracing of power transmission lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is hard problem for electrical technician on site to trace power transformers or power lines to serve customers in 3 phase -4 wires power distribution systems. It is necessary that the correct and fast tracing method is required for load balancing among distribution lines. Old technology use to trace lines with high power impulse injection. Our proposed method uses to trace lines with very small power high frequency signal injection. Simulation models for 3-phase power transformers, 3-phase wire lines, and customer loads are described to investigate the transmission characteristics of high frequency power line carrier. Distribution lines have only a limited ability to carry higher frequencies. Typically power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.8
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• pp.849-857
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• 2009

To guarantee the safety and reliability of obsolete thermal power plants, on site routine patrol in their facilities has been done by human workers. Due to their poor working environments, however, a patrol robot system has been gradually required instead of the human workers from the viewpoint of the workers' safety and work efficiency. For this purpose, this paper presents a patrol robot, controllers, and its control scheme. Especially, this robot system uses a line tracing algorithm, which uses a vision camera instead of IR sensors, and an RFID system for its patrol operation. We confirmed its effectiveness through experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.559-562
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• 2017

In city, tracing of power transmission lines is difficult due to compound installation of overhead and underground lines, transposition, bad view caused by trees or big buildings. It is hard problem for electrical technician on site to trace power transformers or power lines to serve customers in 3 phase -4 wires power distribution systems. It is necessary that the correct and fast tracing method is required for load balancing among distribution lines. Old technology use to trace off-lines with high power impulse injection. Our proposed method use to trace live lines with very small power high frequency signal injection. Typical power transformers in the distribution system prevent propagating the higher frequency carrier signal. The proposed method uses the limited propagation ability to identify the power transformer to serve customers. Two end communication terminals are required to be synchronized between them for determination on electrically same phases. Challenging issue is to achieve synchronization without GPS providing synchronizing time. A novel power transformer and wire identification system is designed and implemented. The system consists of a transmitter and a receiver with power-line communication module. Some experiments are conducted to verify the theoretical concepts in a big commercial building. Also some simulations are done to help and understand the concepts by using MATLAB Simulink simulator.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.511-515
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• 2017

Various walking robot platforms have been developed to carry out missions such as explorations, pass of obstacle or inspections of dangerous environments. In this work, a four legs mechanism based on Jansen mechanism is developed, which can trace a certain line. In order to maximize the tracing speed, mechanism design is performed in multiple phases using m.sketch, EdisonDesign and Arduino programs. In design process, control of power path and optimization of the locus of legs(GL/GAC) are found to be most important. A prototype model is constructed and test run to check the validity of the design optimization.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.6
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• pp.236-241
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• 2006

This paper presents a transfer capability enhancement process using VSC HVDC system which can control active power as well as reactive power. The transfer capability is constrained by stability like voltage stability as well as thermal rating of power system components. Transfer capability of the power system limited by these constraints may be enhanced by reactive power control ability and active power flow control ability of the VSC HVDC system. To enhance the transfer capability of the system using VSC HVDC, selection of the HVDC installation site is performed. In this work, power zones which consist of major power plants and their sinks are identified using power tracing and distribution factor. Alternative route of major AC transmission line in the power zone is identified as VSC HVDC system.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.141-142
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• 2017

In this paper, integrated series and shunt inverter is presented to solve power quality problems in distribution line system. In this configuration consists of series inverter and shunt inverter. Series inverter acts as DVR to compensate voltage during sagging occurred and shunt inverter optimize to inject balance active power from distributed power source like PV system with Maximum Power Point Tracing (MPPT). Finally, the proposed configuration is verified through the PSiM simulation.