• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.11
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• pp.639-646
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• 2003

Nowadays traction motors in the urban rail transit vehicle are controlled by VVVF inverter and have capability of regenerative braking. The algorithms to deal with the regenerating vehicle in simulation for the DC traction power supply is introduced in this paper. Substations have to be separated from the system to represent reverse biased rectifiers in substations. The model of the trains in regenerative braking has to be changed from the ideal current source to the constant voltage source since the train input voltage has to be controlled below the certain train maximum voltage. Some mismatches are unevitable because the constraint of the regenerated power can not be imposed with the constant voltage source. The mismatches represent the unused regenerated power. A computer program is developed to verify the validity of the algorithm. The test run result shows the program behaves as it is expected and proves the algorithm's validity.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1885-1887
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• 2000

In this paper we introduce preventative and diagnostic systems developed to prevent substations from accidental fault of electric power transmitting apparatus. We propose monitoring and diagnostic system for ultra high voltage GIS and main transformer of 765kV substations as an example of preventative and diagnostic techniques being applied in Korea. We also present a guideline to construct and manage an expert system for this purpose. Finally, an engineering solution as a substation management support system is proposed.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.717-722
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• 2007

Most of DC 1500V electric railway substations have adopted diode rectifiers to supply stable DC power. However, the diode rectifiers operate in the first quadrant of the voltage-current plane and thus need regenerative inverters which transfer the surplus regenerative power caused by regenerative braking of electric train sets into the grid. In order to select the proper capacity and installation position of regenerative inverter, it needs to investigate the consumed and regenerative energy of the electric traction substations in advance. This paper presents an analysis of regenerative energy in two substations operating in Seoul Seolleung and Kwangju Yangdong substations. DC line voltage and feeder currents are measured for a day to calculate consumed and regenerative power far four feeders. We calculated an amount of regenerative energy consumed in other feeders and estimated the cost reduction in energy consumption due to the reuse of regenerative energy

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.96.6-96
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• 2001

A high peak power demand at substations will result under Moving Block Signalling (MBS) when a dense queue of trains begins to start from a complete stop at the same time in an electrified railway system. This may cause the power supply interruption and in turn affect the train service substantially. In a recent study, measures of Starting Time Delay (STD) and Acceleration Rate Limit (ARL) are the possible approaches to reduce the peak power demand on the supply system under MBS. Nevertheless, there is no well-defined relationship between the two measures and peak power demand reduction (PDR). In order to attain a lower peak demand at substations on different traffic conditions and system requirements, an expert system is one of the possible approaches to procure the appropriate use of peak demand reduction measures ...

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.77-81
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• 2000

The purpose of this paper is to describe a new measuring method of ground resistance for the grounding system in energized power equipment and substations. It is very difficult to measure the accurate ground resistance in energized power equipment and substations because of the noise conducted from all external connections to the grounding system and harmonics components caused by unbalanced loads and overloads. The ground resistance that is measured with existing methods includes not only the effect of desired signals but also noise components for the measurement period in grounding system. The measured value of ground resistance can entirely be different from actual value. In this paper, to eliminate 60[Hz] power system interference and harmonic components the low-pass filter method was used in the measurement of ground resistance.

• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.240-246
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• 2006

The mathematical model of the power substation is proposed. The substation esteems as a set of the equipment elements which integrated common connections and electromagnetic field. Some capabilities of model represented by both electric networks and a discrete logical model demonstrated by non-directional graph. The model can be useful for solution of the problem of diagnostic of the high-voltage equipment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1556-1560
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• 2007

Energized power transformers in substations make unwelcome noises which propagate to nearby residential areas. As the excessive noise level become a target of public grievance than ever, utilities are seeking solutions to it. This paper introduce a power transformer noise prediction program which can give utilities effective solutions. Once a noise source is given, the program calculates the propagated noise level at certain points. The estimated result is rendered as noise contour map. To validate the accuracy of the program, the predicted noises are compared to measured one in real substations and proven to be acceptable within a margin of 5 percent.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.523-528
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• 2015

A new algorithm for a coordinative control method is proposed with respect to voltage control and system stabilization of local substations. This is accomplished using control cooperation between a static synchronous compensator (STATCOM) and the existing voltage compensation equipment in the steady state and emergency state of a power system. A real-time system analysis was developed by combining a system analysis program with InTouch, which has primarily been used in factory automation for verification. PSS/E was used for the load flow calculation software, Python for language, Intouch as an HMI program, and MS SQL for the database. To test this system, the system in the vicinity of the Migeum and the Migeum substations was modeled and simulated.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.38-41
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• 2002

We have conducted Preliminary investigation to propose a suitable site for superconducting fault current limiter (SFCL) installation in the KEPCOs 154kV grid This investigation limited the application SFCL to the bus-tie position of the grid in the Seoul area. First, we calculated maximum Potential fault current for all substations. Then, among substations where the fault current exceeds the CB capacity, rye selected two substations where buses are being operated untied. For the selected two. S S/S and M S/S. fault currents at the M S/S were estimated to be 22.5㎄ and 24.3㎄ for two buses untied respectively, but 44.2㎄ if buses were tied. Simulation using a hypothetical SFCL of 5 Ohm impedance showed that it controlled the fault current up to 20. 1㎄ for bus-tie Position, 28.4㎄ and 29.9㎄ for both buses. respectively, each of which are under the capacity of the currently installed 31.5㎄ GIS. For both substations a SFCL with 5 Ohm impedance successfully controls the fault current under the CB capacity, and 10 Ohm SFCL may be recommendable to maximize the SFCL effect.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.8
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• pp.387-393
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• 2001

This paper describes an advanced measuring method and precise evaluation of the ground resistance for the grounding system of energized substations and power equipments. A grounding system of substations consists of all interconnected grounding connections of grounded conductors, neutral ground wires, underground conductors of distribution lines, cable shields, grounding terminals of equipments, and etc. It is very difficult to measure the accurate ground resistance of the grounding terminals of equipments, and etc. It is very difficult to measure the accurate ground resistance of the grounding system of high voltage energized substations because of harmonic components caused by switched power supplies or overloads. The conventional fall-of-potential method may be subject to big error if stray ground currents and potentials are present. In this work, to improve the precision in measurements of the ground resistance by eliminating the effects of harmonic components and stray currents and potentials, the investigations of the ground resistance measurement by using a low pass filter in a model energized grounding system were conducted. The accuracy of ground resistance mesurements was evaluated as a function of the ratio of the test signal to noise (S/N). The errors due to the proposed ground resistance measurement method were decreased with increasing S/N and were less than 5[%] as S/N is 10. The proposed ground resistance measurement method appears to be considerably more accurate than the conventional fall-of -potential method. It is allows cancellation of the parasitic resistance of energized grounding systems, to employ the measurement method that allows cancellation of the parasitic effects due to other circulating ground currents and ground potential rises in practical situations.