• Journal of the Korean Solar Energy Society
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• v.28 no.1
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• pp.83-89
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• 2008

This paper presents the characteristics of lightning pver Jeju island and a case of emergency stop of a wind turbine due to lightning. Using the IMPACT ESP sensor to detect lightning, the data on lightning frequency, lightning strength, regional lightning event were obtained and analyzed in detail. The measurement period was for 3 years from 2004 to 2006. As a result, lightning occulted the most frequently in July and August. As for lightning strength, lightning with grades -4 to -6 and +3 to +5 occur ed more frequently. The eastern part of Jeju island had much more lightning frequency compared with the western part of it. Lightning with high grade occurred mainly in offshore site and the coastal region. Furthermore, the data on wind turbine stop caused by lightning was analyzed. Although wind turbine lightning damage was not much in this study, the investigation on lightning damage or lightning faults to a wind turbine should be conducted in Korea to increase availability of wind turbine.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.2
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• pp.146-152
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• 2008

The frequency of lightning is increased due to improbable weather condition and global wanning. This phenomenon increases economical damage as well as human damage. Advanced countries like europe and north america have applied the facility standard of lightning by accumulating a store of quantitative data about lightning research. Lightning facility is composed of the lightning accepting part for induction lightning, ground connected electrode which conducts lightning current. The lightning accepting part is composed of normal rod, horizontal conductor, ESE lightning rod. Moreover, lightning accepting part is taken to use by the method of protection. This paper suggests HEC(Hybrid ESE-Conductor) method which mixes horizontal conductor and ESE lightning rod. This is also discovered by experiment that the starting point of corona discharge current is low, so it is efficient for lightning protection comparing with other methods. Moreover, distribution of electric field is analyzed qualitatively by finite element method. It also results in the relation of the starting point of corona discharge current. Corona discharge current makes minute current about some ${\mu}A$ between the electrodes by the strength of electric field. Also it occurs insulation destruction of gas, and it is developed to the shape of streamer by increase of the strength of electric field. We can find that the initial occurrence of streamer and contact probability of lightning can have advantage after researching the starting point of corona discharge current and discharge current of lightning striking point. This research demonstrates that the suggested HEC method is economically competitive as a lightning protection facility, and it takes a capably perfect role.

• Journal of the Korean Solar Energy Society
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• v.33 no.5
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• pp.60-68
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• 2013

This paper presents the characteristics of lightning over established and scheduled wind farms of Jeju island as well as over specific range of entire Jeju Island. The lightning data for 5 years from 2008 to 2012 was obtained from IMPACT ESP which detects lightning. Lightning frequency, lightning strength and regional lightning events were analyzed in detail, and then the lightning maps of Jeju Island were created. The evaluation of lightning rate was made for all the wind farms of this study. Damage to wind turbines by lightning was found in the existing wind farms. As a result, the eastern part of Jeju Island had more lightning frequency than the western part of the Island. Also, the evaluation of lightning rate was good for all established and scheduled wind farms of Jeju Island. Hankyung is the best place for lightning safety, while precaution should be taken against lightning damage in Kimnyung. Lightning damage to wind turbines occurred in Samdal and Haengwon wind farms, which had the first and the second highest lightning rate of the five existing wind farms.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2356-2363
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• 2015

Localization of lightning strike point (LSP) in the forest is modeled to mitigate the forest fire damage. Though forest fire ignited by lightning rarely happens, its damage on the forest is grievousness. Therefore, predicting accurate location of LSP becomes crucial in order to control the forest fire. In this paper, we proposed a new hybrid localization algorithm by combining the received signal strength (RSS) and the received signal strength ratio (RSSR) to improve the accuracy by mitigating the environmental effect of lightning strike location in the forest. The proposed hybrid algorithm employs antenna theory (AT) model of cloud-to-ground (CG) return stroke lightning channel to forecast the location of the lightning strike. The obtained results show that the proposed hybrid algorithm achieves better location accuracy compared to the existing RSS method for predicting the lightning strike location considering additive white Gaussian noise (AWGN) environment.

• Journal of Aerospace System Engineering
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• v.6 no.3
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• pp.13-18
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• 2012

Every 3000 hour an aircraft is stricken by a lightning. Also the lightning damage to the aircraft during flight are continually occurred due to extreme weather phenomena such as global warming. Under the airworthiness standards, the aircraft must be designed to protect lightning. To show compliance for lightning, the test should be conducted by the actual lightning current and voltage waveform for the actual aircraft or parts. After test, structure damage is detected via visual inspection or NDI. Structure substantiation for damage is to show retaining limit or near limit load capability. This is conducted by test or analysis based on test. Thus, the aircraft should retain structural strength to land safely, even though the damage of aircraft fuselage from Lightning strike are occurred.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.137-143
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• 2014

An investigation on lightning characteristics and damage to wind turbines was performed on Jeju and Gangwon regions. The lightning data from January 2010 to September 2013 detected by IMPACT ESP were collected and analyzed in detail. Hangyeong and Seongsan wind farms of Jeju province and Taebaek, Changjuk, Taegisan and Gangwon wind farms of Gangwon province were selected for this study. Lightning rates and lightning damage events at the six wind farms were compared with each other. Lightning maps for the two regions were drawn using lightning frequency data. As a result, lightning frequency of Gangwon region was higher than that of Jeju region, while lightning strength of Gangwon was weaker than that of Jeju. Lightning rates were assessed to be good for all of the six wind farms. No lightning damage to wind turbines occurred at the two wind farms of Jeju, while some lightning damage to wind turbines took place at the four wind farms of Gangwon.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.438-439
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• 2008

KEPCO has been operating a lightning detection network, KLDNet, to cope with lightning-induced faults. An weather observation for last 40 years shows that heavy rainy days per year and the strength of rain have almost doubled. It could be interpreted as more frequent occurrence of lightning events. In accordance with that, the lightning activities and the mischievous influences, such as transmission faults, have increased. In this paper, the observed data by the network in 2007 is analyzed and compared with ten-years-old-statistics accumulated by the former system, LPATS.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.535-536
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• 2011

This paper studies the validity about a joint operation of neutral wire and overhead grounding wire in combined distribution systems. The overhead grounding wire and neutral wire are currently installed separately and grounded by common. However there is no any ineffectiveness or electrical problem in case of the proposed system, such system can be operated at real distribution system. Therefore this paper describes the suitability of a joint operation through lightning surge analysis on combined distribution systems and analyzes the optimal position of lightning arrester on joint operation of neutral wire and overhead grounding wire. Lightning surge analysis is carried out by EMTP/ATPDraw to obtain the overvoltage of overhead line and underground cable in various conditions such as location and current types of lightning stroke. Over voltage gained by the analysis show that the insulation strength of the joint operation case is not stable compare with the current operation case.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.3
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• pp.269-275
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• 2012

Carbon-fiber reinforced plastic(CFRP) laminates made of nano-particle-coated carbon fibers and damaged by a simulated lightning strike were tested under compression-after-impact(CAI) mode, during which the damage progress due to compressive loading has been monitored by acoustic emission(AE). The impact damage was induced not by mechanical loading but by a simulated lightning strike. Conductive nano-particles were coated directly on the fibers, from which CFRP coupons were made. The coupon were subjected to the strikes with a high voltage/current impulse of 10~40 kA within a few ${\mu}s$. The effects of nano-particle coating and the degree of damage induced by the simulated lightning strikes on AE activities were examined, and the relationship between the compressive residual strength and AE behavior has been evaluated in terms of AE event counts and the onset of AE activity with the compressive loading. The degree of impact damage was also measured in terms of damage area by using ultrasonic C-scan images. The assessment during the CAI tests of damaged CFRP showed that AE monitoring appeared to be useful to differentiate the degree of damage hence the mechanical integrity of composite structures damaged by lightning strikes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.94-99
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• 2011

This paper verified the characteristics of electrical continuity and mechanical strength of steelwork required to use it as a down-conductor in lightning protection system. It was proven that the steelwork in reinforced concrete apartment has an excellent electrical continuity with low resistance(less than 0.2[${\Omega}$].). But it was confirmed that a poor connection between two reinforcement bars can easily cause serious damages of the concrete even with the impulsive current of 50[kA], 10/350[${\mu}s$]. These results of experiments mean that the additional measures are necessary in using the steelwork as the down-conductor of the lightning protection system.