• Journal of Power Electronics
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• v.17 no.3
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• pp.788-797
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• 2017

The power quality of AC electric railways has become an issue worthy of more and more concern. Many active compensators based on power converters have been proposed, but with complex transformers or coupled branches. This paper presents a single-phase cascaded H-bridge multilevel active power filter (APF), which can directly connect to the 27.5-kV power supplies to deal with power quality problems. According to field measured data, the load characteristics are analyzed, and the system configuration and control system are designed based on the load characteristic analysis. Finally, simulation and experimental results verify the effectiveness of the proposed APF system, considering some problems such as the supply voltage fluctuations and transient inrush currents in AC electric railway systems.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.171-178
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• 2013

This paper discusses to conduct experimental verification of two types of micro electric vehicles (EV) in order to realize improvement in electric mileage and shorten a charging time of the battery. First, electric double layer capacitor (EDLC) systems to use as a secondary battery are proposed. The internal resistance of EDLC is small compared with a rechargeable battery, and it is suitable for momentary charge-discharge of EV. Next, control circuits of the capacitors to increase the regenerative electric power are utilized. Then, a novel method to charge a main battery of the EV is introduced. Finally, experimental results demonstrate the validity of the proposed method.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.211-224
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• 2020

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.1298-1300
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• 1996

The application field of photovoltaic system which has no-pollution and no-fuel distinctives is being spreaded inspite of its high installation cost. At present, there are three PV systems within the country, which were already installed and have been operated to supply the electric power in remote island. In this paper, the electrification plan of our government on the unelectrified or subelectrified islands is introduced, and the operation results of three PV systems are investigated to discuss the diffusion possibility of PV system as a power supply option.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.218-219
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• 2006

This paper is about modeling on 1500V DC electric railroad system. Electric railroad systems have peculiar characteristics against other electric system. The characteristics arc that the railroad systems have electric vehicle loads which are power-varying and location-varying with time. Because of this load characteristic, the electric railroad system modeling which reflects its own characteristics on EMTDC simulation could not be achieved. However, to reflect load characteristic on EMTDC, this paper suggests electric railroad system modeling by using TPS (Train Performance Simulator) that was developed in Korea Railroad Research Institute. A TPS program has various kinds of input data, such as operation condition, vehicle condition, and power system condition. By these data, TPS calculates mechanical power consumption and location, especially it decide electric power consumption on the basis of the fact that consumed electric and mechanical power are equal. Moreover, on this paper, movement of vehicle is reflected on EMTDC simulation as variation of feeder impedance. Also, an electric vehicle load is modeled as time-varying constant power load model.

• Fire Science and Engineering
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• v.29 no.3
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• pp.53-58
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• 2015

The number of high-rise buildings and skyscrapers has increased drastically, and accordingly, the power capacities and main line lengths of electric power systems for fire protection are also rapidly increasing. This is generating new of problems like shortages in power capacities and increases of main line voltage drops outside of the rated voltage range. This problem can have serious effects on fire protection systems and a variety of electric devices may not work properly in emergencies. As such, theoretical calculations were performed for these systems in an actual fire protection facility. The problems in the electric power system were extracted and analyzed, and the results show that it is necessary to search for new measures for the safe and rational design and operation of electric power systems for fire protection.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.109-113
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• 1987

This paper briefly introduces a strategy of data links between EMS and SCADA systems for the KEPCO's EMS project. For the data links, front end/communication processors are adopted that provide for protocol conversion and communication processing in parallel with EMS/SCADA processing. The data link configuration for a communication channel is point to point links. The EMS - hardware and software - has capability of handling links utilizing both bisync protocol and X.25 (Level 1 and 2)protocol for the data link protocol.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.936-937
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• 2008

As a micro computer or micro processor technology has been advanced, the essential part which consists of electric power system has been changed into intelligent electronic device(IED), that is one kind of embedded system. There are already many parts changed into digital from analog in control and maintenance devices of electric system. These trends make advanced and novel concepts of devices and systems, that we couldn't even imagine in the analog circumstances. Now, the rate's of change is comparatively slower than IT field that is mainly represented by mobile communication, but that is a big change in the history of electric industries. Some people in those field called it Power-IT, and there have been many kinds of researches. Accelerated systems to go digital, users always and continuously demand more convenient, practical, and new functions. So, a lot of electric system manufactures have had tasks realizing many kinds of functions in an electronic device. According to the high-end technologies in semi-conductor and micro-computer field, manufactures can fully satisfy almost all of customer's needs, but there are other kinds of problems, such as large amount of program code, increasing complexity in proportion with program amount, and the hardness of maintenance and revision of the program. So nowadays, the necessity of embedded OS was emerged as a solution, and many researchers and manufactures have concentrated on studies related to embedded OS and its application.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.141-144
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• 2002

Recently, the operation of power distribution systems has become more difficult because the peak demand load is increasing continuously and the daily load factor is getting worse and worse. Also, the consideration of deregulation and global environment in electric power industry is required. In order to overcome these problems, a study on the planning and operation in distribution systems of dispersed generating sources such as fuel cell systems, photovoltaic systems and wind power systems has been performed energetically. This study presents a method for determining an optimal operation strategy of dispersed co-generating sources, especially fuel cell systems, in the case of both only electric power supply and thermal supply as well as electric power supply. In other words, the optimal operation of these sources can be determined easily by the principle of equal incremental fuel cost and the thermal merits is evaluated quantitatively through Kuhn-Tucker's optimal conditions. In order to select the optimal locations of those sources, an priority method using the comparison of total cost at the peak load time interval is also presented. The validity of the proposed algorithms is demonstrated using a model system.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2543-2545
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• 2002

There are many applicable services such as remote metering, load control, distribution line automation, Pole transformer Monitoring having their own networks in the electric power company. The application of the optical network technology as the back-born network to the Automation Systems in KEPCO is potentially beneficial in reliability, speed, and expandability. The 1-core and 2-core optical modems were developed and used by the Distribution Automation System. But, They had some disadvantages and advantages. So, We designed the new optical modems applied each advantages. This paper presents some of design efforts and test results for the multi-channel optical modem at KRPRI.