• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.214-218
• /
• 2008

Because on the high-tension underground distribution line of an electric railway high voltage XLPE Cable two or three circuits between railway stations with a standard as receiving transformer facilities are established at a $30km{\sim}50km$ interval, reactive power in which the phase of a current is larger than that of a voltage is supplied when trains are not working, so when there are no loading or low loading as night. Due to the long-distance trend of the underground distribution system on an alternating current railway distribution line, the terminal voltage of a transformer is over the standard voltage, and after all, commercial cycle overvoltage is continued. To solve this problem, the shunt reactor is installed in middle of power distribution lines to maintain receiver voltage meted under the allowance regulation through control of the reactive power. Also, in case that the thickness of single cable is over $60mm^2$ and length of line is about over 30km, a circuit breaker is broken by shorting shunt ability of charging current in excess of shunt current(31.5A.rms). Therefore, this thesis presents installing the location of shunt reactor for quantitative analysis by using optimum algorism for compensation and control of the charging current.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.462-466
• /
• 2021

DVR is a device that compensates for voltage fluctuations in distribution lines and is generally used in combination with a device that compensates reactive power and improve power factor. Such a coupling compensator has the disadvantage of being relatively difficult to control and bulky. In this paper, mathematical analysis of the maximum magnitude of the compensation voltage, phase angle, compensable reactive power and active power was performed in order to simultaneously compensate the reactive power and voltage fluctuation of the distribution line by applying the power angle control method of the DVR. A control algorithm for charging active power to the battery and supplying stored energy when the voltage is changed was developed and the results were confirmed through Matlab simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.1006-1009
• /
• 2015

Power-line communication technology is proposed to identify power transformers to serve customers in 3 phase -4 wires power distribution systems. Mathematical 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. From the analysis, distribution line cable circuits 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. A novel power transformer 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.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.54 no.6
• /
• pp.409-416
• /
• 2005

For broadband high-data-rate power line communication with the allocated frequency bandwidth from 2 to 30 MHz on medium voltage (MV) distribution power lines, a signal coupling unit is developed. The coupling unit is composed of a coupling capacitor for coupling communication signal, a drain coil, and an impedance matching part. The coupling capacitor made of ceramic capacitor is designed for transmission property of better than 1 dB in the frequency range. The drain coil is used for preventing low frequency high voltage from junction of medium voltage power line in case that a coupling capacitor is not working properly any more. Also, using ferrite core, a novel broadband impedance matching transformer is developed. A complete coupling unit with a coupling capacitor, a drain coil, and a matching transformer is housed by polymer for good isolation and distinguishing from high voltage electric facilities. Each is fabricated and its frequency behavior is tested. Finally, complete signal couplers are equipped in a MV PLC test bed and their performance are measured. The measurement shows that the coupling capacitor works excellently.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.475-479
• /
• 2001

Compensation characteristics or active filters based on voltage detection are investigated. These active filters act equivalently as a passive circuit so that they may not cause practical problems such as stimulation of resonance in the distribution lines. Thus, these active filters can be used as the general-purpose active filters. On the other hand, these active filters may have a possibility of the anti-resonance associated with the line inductance of the distribution lines. In this paper, the relationship between the anti-resonance and the control parameters of the proposed active filters is clarified. Some methods to avoid the problems due to the anti-resonance are investigated. Experimental results are included to confirm the validity of the investigation presented in this paper.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.157.5-157
• /
• 2001

Generally, the application of Programmable Logic Controller PLC is emphasized on the Process Control. This paper presents Neurofuzzy application, Which can estimate the distance to a fault by means of PLC and based up on the Electrical Power System theory and ground resistance. The case study refers to the distribution lines of the Provincial Electricity Authority (PEA). Also, the thesis is supposed to be of much benefit: saving time both to go to the scene and to clear fault, reducing unpleasant impacts on customers and stabilizing reliability of the distribution lines.

• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.966-968
• /
• 1997

Our country is still suffering from much work outage, nearly 80% of total outage time, in 22.9kV-Y multi-grounded distribution lines. Therefore, KEPCO which is the sole utility owned by the Korean government has developed outage-free work techniques to improve the reliability of power supply in Our country. This paper is to introduce the developing process and good effects of outage-free work techniques, and the equipment developed and applied in Our country. This paper will aid many utilities to try to reduce the work outage.

• The International Journal of Costume Culture
• /
• v.2 no.1
• /
• pp.31-42
• /
• 1999

The category killer that has been rapidly growing mainly in advanced countries since early 1990's, is a mew distribution model which aims for obtaining market controlling power by surpassing competing businesses in a specific area of products. The domestic situation of category killers is very different from that of advanced ones abroad since it has just been introduced into the Korean market. At the moment, there are only 10 or so companies operating in the market : Geopyung's , Taeheng's , Midopa's , of Sinsegye Department store, adn of Yerim International. The purpose of this study is to examine problems of domestic companies in the present market by analysing the operation status of category killers in domestic markets as well as foreign ones, and to suggest a counter-strategy of category killers for the distribution environment of the 21st century to improve the competitiveness of Korean distribution industry. The competitiveness of category killers lies above all in products lines. Category killers are equipped with the greatest number of products lines among those of competing businesses due to maximized product selections in an limited range. Another source of competitiveness may be found in balanced strategy positioning. That is to say, category killers are in a position where they can adjust policies towards any of the three purposes while aiming at them altogether : prices of discount stores, products range of specialty stores, and customer service level of department stores. It is also necessary for efficient store operation to use information technology such as electronic data interchange (EDI), electronic pose system(EPOS) and electronic funds transfer (EFTPOS). As for the cost structure, category killers can gain an advantage over other business since operating cost of various sections can be saved. There are, however, certain risks that category killers with strong competitiveness may influence on other businesses a great deal and even facilitate their decline. Yet it seems that the growth of category killers will be more viciously restrained by continuous challenges from other businesses. The distribution industry is supposed to develop through such competition and restraint.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.21 no.5
• /
• pp.453-456
• /
• 2016

The major causes of electrical fire in low-voltage distribution lines are classified into short-circuit fault, overload fault, electric leakage, and electric contact failure. The special principal factor of the fire is electric arc or spark accompanied with such electric faults. This paper studies the development of an electric fire prevention system with detection and alarm of that in case of parallel arc fault occurrence in low-voltage distribution lines. The proposed system is designed on algorithm sensing the instantaneous voltage drop of line voltage at arc fault occurrence. The proposed detector has characteristics of high-speed operation responsibility and superior system reliability from composition using a large number of semiconductor devices. A new sensing control method that shows the detection of parallel arc fault is sensed to ripple voltage drop through a diode bridge full-wave rectifier at electrical accident occurrence. Some experimental tests of the proposed system also confirm the practicality and validity of the analytical results.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.8
• /
• pp.1532-1537
• /
• 2009

Nowadays the diversity and large-capacity of electric appliances are strong effect on electrical fires augment in an alarming way. But, as the inactive response characteristics of the existing RCD (Residual Current protective Device) used on low voltage power distribution lines, so control of overload and electric short circuit faults, major causes of electrical fires, are not enough. Therefore this paper is confirmed the unreliability of the existing RCD by electrical faults simulation and is proposed a auxiliary trip device of RCD by using a high precision current sensor (namely, reed switch) for the prevention of electrical disasters in low voltage power distribution lines caused by overload or electric short circuit faults. The sensitive reed switch in the proposed ATD (auxiliary trip device) exactly detects the increased magnetic flux with the overload or the short current caused by a number of electrical faults, and then rapidly cuts off the existing RCD. The proposed auxiliary trip device of RCD is confirmed the excellent characteristics in response velocity and accuracy in comparison with the conventional circuit breaker through various operation performance analysis. The proposed ATD can also prevent electrical disaster, like as electrical fires, which resulted from the malfunction and inactive response characteristics of the existing RCD.