• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.8
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• pp.701-709
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• 2001

In this days, heat pipe heat sink has been widely applied to power controllers for railway substations to remove heat from power semiconductors(diodes or thyristors). The heat pipe heat sink consists of a aluminum heating block for mounting the thyristor, 2~3 heat pipes and large number of aluminum fins. The present study was to get fundamental informations of the structure, design parameters and heat transfer performances of heat pipe heat sink. Series of operational test for a unit with 3 heat pipes were performed and its heat flow circuit was analysed from the experimentally obtained data on wall temperature distribution. Total resistance was ranged 0.02~$0.03^{\circ}C$/W for a power range from 40W to400W. The time to get the steady state was approximately longer than 20 minutes, and overshooting was not occurred during start up operation.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.407-416
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• 2008

The OCC of Seoul Metro whose operation began in 1974 is in charge of conveying 4,000,000 passengers across 117 subway stations in travel zones of 134.9Km in length. It continues to strive to ensure passenger safety by applying state-of-the-art-technology to each control system without delay. The power control center especially designed to provide power system operations for all stations of Seoul Metro(Line 1 to 4) and the rolling stocks implements preventive safety systems with the real time power system operational information on changes in conditions from the field through the power SCADA system(41 substations, 117 stations, 137 terminal units). This paper reports the differences of each line's power SCADA system(power SCADA systems of Seoul Metro(Line 1 to 4)), the roles and functions of the system, and the system operating characteristics and limits from the standpoint of the operator.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.177-185
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• 2005

This paper proposes an expert system that can enhance the accuracy of real-time bus reconfiguration strategy by adopting the local minimum tree search method and that can minimize the spreading effect of the fault by considering the operating condition when a main transformer fault occurs in an automated substation. The local minimum tree search method is used to expand the best-first search method. This method has the advantage that it can improve the solution performance within the limits of the real-time condition. The inference strategy proposed expert system consists of two stages. The first stage determines the switching candidate set by searching possible switching candidates starting from the main transformer or busbar related to the event. The second stage determines the rational real-time bus reconfiguration strategy based on heuristic rules from the obtained switching candidate set. Also, this paper proposes generalized distribution substation modeling using graph theory, and a substation database based on the study results is designed.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.77-79
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• 2003

New cities and industrial complexes are being developed actively because of the government policies aiming population distribution and vitalization of construction industry. To determine the investment amount, number of power lines and substations for stable power supply to newly developed residential and industrial complexes, accurate estimation of power demand is necessary. This paper propose standards for the estimation of power demands for power company and construction company to settle the debates surrounding this issue. Through a survey and analysis of existing areas, new standards that will enable more accurate estimation of power demands in new cities complexes to be developed in the future are established by calculating the average load density, load factor, utilization factor by area, use and building size after dividing the facilities into building type and the areas into the areas planned to be developed and the areas not yet planned to be developed.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.220-223
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• 1998

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL) for the 154 kV transmission line between the Gaepo and Sungnam substations. The fault current increased up to 39 kA during an artificial ground fault. The SFCL with 100 ${\Omega}$ impedance after quench limited the current to 15 kA within a half cycle. This limited current is well below the upper limit of a circuit breaker, suggesting that the impedance of the SFCL in the transmission line is sufficient.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.12
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• pp.2213-2219
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• 2008

Customer complaints on noise from the power transformer have been increased because of their concerns on environment. In order to solve fundamental noise problem of the transformer, KEPCO and domestic transformer manufacturers are developing 55 dBA class low noise transformers. To check accordance of the noise abatement law, we study relation between transformer noise level and substation border noise level. We present 'noise level of the substation border' under operating conditions and transformer noise level change. We also present an appropriate noise level of the transformer that satisfy the noise abatement law for outdoor substations.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.297-303
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• 2012

This paper presents the simulation results for the analysis of a lightning surge, switching transients and very fast transients within a thermal plant. The modeling of gas insulated substations (GIS) makes use of electrical equivalent circuits that are composed of lumped elements and distributed parameter lines. The system model also includes some generators, transformers, and low voltage circuits such as 24V DC rectifiers and control circuits. This paper shows the simulation results, via EMTP (Electro-Magnetic Transients Program), for three overvoltage types, such as transient overvoltages, switching transients, very fast transients and a lightning surge.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.339-344
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• 2014

An offshore wind power plant (WPP) is very expensive and different from an onshore wind power system in many ways. There has been a continuous increase in the capacity of the offshore WPPs. Therefore it is essential to analyze the feasibility and reliability of the offshore wind power to optimize their redundancy. Besides, it is very important to study a planning for grid interconnection of adjacent offshore WPPs. This paper proposes a economic evaluation method to interconnect with adjacent offshore substations in offshore wind power grid. Also, we suggest the probabilistic reliability method to calculate a probabilistic power output of the wind turbine and a cost of the expected energy not supplied that is used as the reliability index of the power system.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.534-539
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• 2015

The DC overhead line voltage of an electric railway substation swings depending on the accelerating and regenerative-braking energy of trains, and it deteriorates the energy quality of the electric facility in the DC railway substation and restricts the powering and braking performance of subway trains. Recently, an energy storage system or a regenerative inverter has been introduced into railway traction substations to diminish both the variance of the overhead line voltage and the peak power consumption. In this study, the variance of the overhead line voltage in a DC railway substation is modelled by RC parallel circuits in each feeder, and the RC parameters are estimated using the recursive least mean square (RLMS) scheme. The forgetting factor values for the RLMS are selected using simulated annealing optimization, and the modelling scheme of the overhead line voltage variation is evaluated through raw data measured in a downtown railway substation.

• The Transactions of the Korean Institute of Power Electronics
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• v.20 no.6
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• pp.573-579
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• 2015

A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.