• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1108-1110
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• 1999

This paper describes the comparison results on electrical characteristic changes of ZnO blocks by lightning impulse current. The five types of ZnO blocks used in lightning arrester for distribution lines have been estimated repeatedly till about 400 times by a standard lightning impulse current of 3kA, $8/20{\mu}s$, and changes of the performance characteristics of them to operation times were examined and compared quantitatively every fifty times discharge. It is expected that the result will be useful to diagnose the soundness of ZnO blocks or lightning arresters, and to develope deterioration diagnosis device for them.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.800-802
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• 1997

After flashover occurs on the overhead distribution line by lighting strokes(direct or induced), the power frequency arc current continues. If lightning flashover occurs on the overhead lines using covered conductors, the power frequency art current with fixed path overheats the conductor, and arc fusion fault can be occurred. There are two categories protecting or reducing methods of arc fusion faults caused by lightning stokes. - Reducing lightning flashover rate : G/W, LA, etc. - Protection by AFPD(Arc Fusion Protection Device) : power follow current interruption. This paper presents lightning surge phenomena on overhead distribution lines and protecting performance of arc fusion Protection devices to the lightning strokes nearby overhead line.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.283-288
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• 1996

This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.544-551
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• 2020

Reactor control is a standout amongst the most vital issues in the nuclear power plant. In this paper, the optimal design of variable structure controller (VSC) based on the lightning search algorithm (LSA) is proposed for a nuclear reactor power system. The LSA is a new optimization algorithm. It is used to find the optimal parameters of the VSC instead of the trial and error method or experts of the designer. The proposed algorithm is used for the tuning of the feedback gains and the sliding equation gains of the VSC to prove a good performance. Furthermore, the parameters of the VSC are tuned by the genetic algorithm (GA). Simulation tests are carried out to verify the performance and robustness of the proposed LSA-based VSC compared with GA-based VSC. The results prove the high performance and the superiority of VSC based on LSA compared with VSC based on GA.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1498-1499
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• 2006

It has been reported that more than 50% of breakdown in transmission line for 154kV and above is due to lightning stroke. The flashover failure due to lightning stroke causes outage, voltage drop and instantaneous outage, Therefore line arrestors have been used in transmission line for protection from lightning stroke. In this paper, we describes electrical characteristics and performance test of line arrestor for transmission line.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.5
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• pp.170-175
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• 1983

A simplified method for the estimation of lightning performance of transmission Lines is described. Only one stroke current wave shape was used and the potentials of tower top and crossarms were computed at the two time points to obtain the critical stroke current for insulator flashover. Variation of the critical stroke current due to power frequency voltage was also takes into account. An applied example on 345KV Line model was shown and the calculated result was compared with the estimating curve suggested by Clayton & Young.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.7
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• pp.41-48
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• 2009

Grounding impedance depends on the frequency of current flowing into a grounding system lightning in particular has a broad frequency spectrum from some tens of Hz to a few MHz. So the grounding impedance related to transient currents such as lightning should be measured. In this paper, the grounding impedances of vertically-driven ground rods of 10, 30 and 48[m] long are measured and analyzed as functions of the frequency of injected current and the feeding point. As a result, the longer the ground rod is, the lower the steady-state ground resistance is. However the grounding impedance of a vertically-driven ground rod at a high frequency is significantly increased. It is not always true that low grounding impedance follows from a low steady-state ground resistance. It is important to evaluate the high frequency performance of grounding systems for protection against lightning.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.760-768
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• 2011

The performance of transmission lines and its shielding design during a lightning phenomenon are quite essential in the maintenance of a reliable power supply to consumers. The leader progression model, as an advanced approach, has been recently developed to calculate the shielding failure rate (SFR) of transmission lines using geometrical data and physical behavior of upward and downward lightning leaders. However, such method is quite time consuming. In the present paper, an effective method that utilizes artificial neural networks (ANNs) to create a metamodel for calculating the SFR of a transmission line based on shielding angle and height is introduced. The results of investigations on a real case study reveal that, through proper selection of an ANN structure and good training, the ANN prediction is very close to the result of the detailed simulation, whereas the Processing time is by far lower than that of the detailed model.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1420_1422
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• 2009

Lightning currents are one of major influences on the dynamic performance of counterpoise. High lightning current causes the dynamic grounding performance of counterpoise due to very fast fronted pulses. The previous analysis has often been based on quasi-static approximation that can not be applicable to very fast fronted pulses. To extend the analysis for fast fronted pulses in this paper, the full-wave analysis method based on the rigorous electromagnetic-field theory approach is used and the effects of the ionization of the soil are disregarded. Based on the simulation results, the empirical formulas applicable for slow and fast fronted lightning current pulses are reviewed; therefore, the validity of the theoretical approach is verified through comparison between the calculated and measured results.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2361-2363
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• 1999

The conventional SiC-type of lightning arresters in distribution systems has been replaced by ZnO-type because the ZnO-type has characteristics such as outstanding non linearity, high energy absorption capability, surge suppressing performance, and excellent response to abrupt wave. Out of the various types of lightning arrester failures, some which have been often reported could be prevented in advance. Therefore, the preventive countermeasures which can cope with the failures are strongly required. This paper summed up and analyzed the lightning arrester failures which occurred, from 1983 to 1992, in distribution systems in order to provide fundamental data, classified by year, to make countermeasures.