• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.12
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• pp.670-677
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• 2004

The Conventional approach for estimating the locations of transmission line shunt faults has been to measure the apparent impedance to the fault from a line terminal and to convert the reactive component of the impedance to line length. But, these methods do not adequately address the problems associated with the fault location on distribution systems. This thesis presents a technique that estimates the location of shunt fault on a radial distribution system that has several single and multiphase laterals. Tapped loads and non-homogenity of the distribution system are take into account. The developed technique, which can handle shunt faults was tested to evaluate its suitability. Results from computer simulation of faults on a model of a 25KV distribution lines like real system are presented. The results approved that the proposed technique works well for estimating the locations of the distribution line shunt faults.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.865-870
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• 1998

We propose a multifunctional power line compensator (PLC) which can individually compensate multiple impediments at the same time. The PLC has the flexibility to share power to each compensation according to commands, this improving the working rate. We constructed a 100kVA PLC model including a controller with digital signal processor (DSP) to realize a multifunctional compensation were obtained.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.510-510
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• 2012

반도체, 디스플레이, 태양광 등의 공정에서 사용되는 웨이퍼의 크기가 증가하고, 생산률이 플라즈마의 밀도에 비례한다는 연구 결과가 발표되면서 대면적 고밀도 플라즈마 소스 개발에 대한 연구가 활발히 진행되고 있다. 특히, ECR, ICP, Helicon plasma 등 고밀도 플라즈마 소스에 대한 관심이 높아지고 있다. 이에 따라, 여러 개의 ICP를 결합한 multiple ICP를 이용해 대면적 고밀도 플라즈마 소스 개발을 진행했다. Multiple ICP의 경우 각 ICP 소스에 같은 power (current)를 공급해야만 균일한 플라즈마 방전이 발생되어 균일도를 확보 할 수 있다. Current controller 같은 추가적인 장비를 설치하지 않고, power를 분배하는 transmission line을 coaxial 형태로 설계하고 같은 길이로 병렬 연결함으로써 각각의 ICP소스에서 균일한 플라즈마를 방전시킬 수 있었다. Power generator에서 보는 각 ICP의 total impedance는 각 ICP 소스의 impedance와 coaxial 형태의 transmission line의 characteristic impedance, frequency, 길이의 함수로 구할 수 있고, 이 total impedance가 일정하기 때문에 current가 균등하게 분배되어 각 ICP소스에 균등한 power 분배가 가능한 것이다. 실질적으로 ICP 소스의 impedance는 플라즈마 방전 유무에 따라 변화하기 때문에 일정하게 유지하는 것은 어렵다. Transmission line의 characteristic을 사용함으로써 ICP의 impedance의 변화에 상관없이 Total impedance를 일정하게 유지시킴으로써 균등한 power 분배가 가능하다는 것을 연구했다. Frequency는 13,56MHz, characteristic impedance를 $50{\Omega}$ (coaxial cable)으로 고정하고, ICP 소스의 플라즈마 방전 유무/antenna turn/소스 위치에 따른 total impedance를 transmission line의 길이에 따라 측정하고, 이를 이론값, 그래프와 비교하였다. 특정 length에서 플라즈마 방전 유무(ICP의 impedance 변화)와 상관없이 비교적 일정한 total impedance를 유지하는 것을 확인 했다. 이것은 특정 길이를 갖는 coaxial형태의 transmission line를 연결하면, total impedance는 플라즈마 방전 유무로 발생하는 ICP의 impedance 변화와 상관없이 일정하게 유지되어 각 ICP소스에 균등한 파워 분배가 가능하다는 것을 보여준 결과이다. 이것을 토대로 frequency에 따라(또는 characteristic impedance에 따라) 균등한 파워 분배가 가능한 coaxial 형태 transmission line의 특정 길이를 구할 수 있고, 대면적 소스에서 균등한 파워 분배를 위한 병렬연결에 적용할 수 있을 것이다.

• 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.30-36
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• 2015

The formulation of calculation method for electromagnetic inducing current by aerial power distribution line is established. Nearby telecommunication cables can be induced due to the leakage of neutral current because the neutral line of power distribution is grounded at every 50 m distance. By the existing calculation method, the neutral line is regarded as a shielding conductor and the neutral current roles as an inducing current. So the error range to real measurement value is largely extended because the changing effect of leakage current flowing in the ground is not reflected. The leakage current returns to the power substation through the ground and is cumulated as being closer to the substation. When this practical inducing mechanism is applied, the deviation rate of calculation can be drastically reduced within about 100 % range compared to 1000 % of the exsiting method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.3
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• pp.472-480
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• 2007

This paper analyzes overvoltage on testing line for various parameter effect examination. Model systems consist of overhead line and underground cable. The model considered actual characteristic data of distribution lines. and will be constructed at testing yard. The simulations were performed under various line configuration such as cable kinds, cable length, lightning wave, lightning wave time, transformer and branch circuits. The simulation models are established by EMTP/ATPDraw and Line Constants are calculated by ATP_LCC. When lightning surge strikes on conductor of overhead line, EMTP/ATPDraw calculates overvoltage in many cases. Simulation results will be compared with real testing results at testing yard. The compared results will be used to establish protection methods in actual underground distribution systems.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.729-736
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• 2013

Power grids are large complicated networks in use around. An absolute phase value for a particular unknown-phase line at a local site should be identified for the operation and management of a 3-phase distribution network. The phase shift for a specific point in the line, as compared with a phase reference point at a substation, must be within a range of ${\pm}60^{\circ}$ for correct identification. However, the phase shift at a particular point can fluctuate depending on the line constants, transformer wiring method, line length, and line amperage, etc. Conducted in this study is a theoretical formulation for the determination of phase at a specific point in the line, Simulink modeling, and analysis for a distribution network. In particular, through evaluating the effects of unbalanced current loads, the limitations of the present phase identification methods are described.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.180-182
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• 1992

In spite of recent stagnation, the rate of electric consumption has highly grown in accordance with a high cultural livings, Also, a usage of electric energy is growing with development of multi-information society. To make the matter worse, hard work of highest order is required because distribution system are widely spread and complex. And consummers demand for the electricity of good quality and it is obstracle to be not able to train related technitian for maintenance without an interruption of electric power. It is sure the counterplan of uninterruption of electric power is very necessary. In this paper, considering the working circumstances, we presented the necessity of work method, the effects and the future prospect for uninterruption power supply.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.3
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• pp.431-436
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• 2009

As the telecommunication lines bring into widespread use, one of the most important aspects related to power distribution systems is effectively to evaluate the effect on the telecommunication lines from power lines. One of the efficient methods to evaluate the effect is to measure the induced voltage of a telecommunication line as a result of a ground-loop. If the power lines cause high induced voltage, the ground reference in the telecommunication lines is no longer a stable potential, so signals may ride on the noise. A ground loop is common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the arrangement between the power lines and telecommunication lines. When a multi-path connection between the power lines and telecommunication line circuits exists, the resulting arrangement is known as a ground loop. Whenever a ground loop exists, there are potential for damages or abnormal operations of the telecommunication lines. The power lines can induce the voltage on the communication line. The effects can be calculated by considering the inductances and capacitances. However, if we assume that there are only power lines, it doesn't have a practical meaning because there are conductors with other purpose in the neighborhood of the lines. If we consider that case, we need more complex system. Therefore we suggest more complex system considering the conductors with other purpose in the neighborhood of the lines. The neutral wires and the overhead ground wires are considered for calculating the induced voltage. We assume that there are the messenger wires beside the power line as a result of increased use of them. The main purpose of this paper is a study on a shielding effect of messenger wires in the distribution lines. EMTP(Electro-Magnetic Transients Program) program is used for the induced voltage calculation.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.419-425
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• 2020

DC distribution system has been evaluated as an excellent one in comparison with existing AC distribution network because it needs fewer power conversion stages and the full capacity of the equipment can be used without consideration for power factor. Recently, research and development on the implementation of DC distribution networks have been progressed globally based on the rapid advancement in power-electronics technology, and the technological developments from the viewpoint of infrastructure are also in progress. However, to configure a distribution network which is a distribution line for DC, more accurate and rapid introduction of analysis technology is needed for the monitoring, control and operation of the system, which ensure the system run flexible and efficiently. However, in case of a bipolar DC distribution network, there are two buses acting as slack buses, so the Jacobian matrix cannot be configured. Without solving this problem, DC distribution network cannot be operated when the network is unbalanced. Therefore, this paper presented a comprehensive method of analysis with consideration of operating elements which are directly connected between neutral electric potential caused by the unbalanced of load in DC distribution network with bipolar structure.