Accuracy of LLP system and lightning frequency map evaluated from transmission line faults

The accuracy of an LLP system and a lightning frequency map are evaluated by using transmission line faults in the Hokuriku area from November 1993 to October 1996. The accuracy and efficiency of the system are calculated by statistical methods. From these results, a lightning frequency map with a 10-minute grid was proved that can replace the Isokeraunic Level Map with a 15-minute grid now used for lightning protection design. However, the correlation between the number of detected lightning flashes and transmission line faults in each mesh was found to be weak. This result suggests that a more detailed analysis taking into account the length of the transmission lines in each mesh is necessary. The correlation is stronger in winter than in summer, despite the fact that there is a difference in the lightning current distribution in each mesh in winter. This characteristic can be explained if upward flashes from transmission lines are dominant among lightning faults in winter. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 45–57, 1999     

High‐current lightning discharges in winter

Lightning electric‐field waveforms related to power line faults in winter have been identified. Most of those waveforms appear to be associated with upward lightning discharges with absolute peak currents of over 100 kA. They are quite different from common return‐stroke waveforms, and the lightning discharges which produce these characteristic waveforms are called GC (Ground to Cloud) flashes. These high‐current lightning discharges are distributed around the coastline in different ways depending on their polarities. The spatial distributions of high‐current lightning discharges around Japan are also investigated. It is revealed that the region of Honshu Island along the coastline of the Sea of Japan belongs to the area in which the density of high‐current lightning flashes is the highest in Japan through the year. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 8–15, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20874     

500kV同塔双回输电线路反击耐雷性能分析

与单回500 kV输电线路相比,同塔双回500 kV输电线路杆塔高度增加,引雷面积增大,将直接影响到线路的耐雷水平。文章依据先导发展闪络判据,模拟电弧的非线性特性,建立了绝缘闪络模型。利用电磁暂态仿真软件（ATP-EMTP）,搭建了500 kV同塔双回输电线路反击耐雷性能仿真电路,分析了杆塔高度、冲击接地电阻和工频电压等因素对线路反击耐雷性能的影响。结果表明：杆塔高度增加后,线路反击耐雷水平显著降低;杆塔冲击接地电阻的增大,将导致线路跳闸率上升,在电阻较高的情况下尤为明显;同时工频电压对500 kV同塔双回输电线路耐雷性能影响尤为明显,因此,在500 kV同塔双回输电线路的设计中应充分考虑工频电压对线路耐雷性能的影响。     

基于雷电定位系统的电网防雷研究

传统的雷电地域分布采用雷电日(雷暴日)的概念,但所有可听雷声中云间雷占有一定比例,而只有地面落雷密度才对电网防雷有影响.从高级调度中心的建设需求出发,根据雷电定位系统统计数据计算出地区落雷密度,从而使华东地区线路跳闸率计算方法更精确,可供防雷的分析研究参考.     

雷电过电压仿真中非线性元件的建模(英文)

The paper presents some problems of lightning overvoltage modeling in transmission lines with nonlinear elements.The presented results were obtained mostly for fast front transients of subsequent lightning return stroke currents.The effectiveness of numerical algorithms of nonlinear models and possibilities of their development for such transients are analyzed.Computer simulations carried out by application of EMTP show that nonlinear models of back-flashover and ZnO arresters work properly,while the implemented corona model can not be used for relatively large peak values of subsequent lightning return-stroke currents.     

Study of lightning current by remanent magnetization

A study of remanent magnetization is made at the areas of lightning strikes. In the case of triggered lightning (Okushishiku, Hokuriku district), the magnetic direction of the specimens shows a clockwise rotation pattern around the point of lightning strike. At an archaeological site in Miyagi Prefecture, an anticlockwise pattern of the magnetic direction was detected. These results indicate that a stable remanent magnetization is acquired by the strong magnetic field induced surrounding the lightning current, both in negative and positive lightning flashes. Also, a detailed analysis of magnetization clarifies the electric current flow underground caused by the lightning. The study of remanent magnetization will become a useful method to elucidate the path of the lightning current. © 1998 Scripta Technica, Electr Eng Jpn, 123(4): 41–47, 1998     

Lightning occurrence data observed with lightning location systems of electric power companies in Japan: 2009–2013

Nine electric power companies in Japan have been collecting lightning data with lightning location systems. Five years of the lightning data (2009–2013) are summarized and analyzed in this paper. The recent annual number of lightning flashes of which the current is more than 10 kA in Japan is around 1 million. The variations of lightning occurrence characteristics by areas, seasons, and so on, are clarified. Meteorological conditions that may affect lightning occurrence are also discussed. Furthermore, we show that there is a clear correlation between the number of lightning strikes and the outage rate of transmission lines. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Classification of lightning damage to wind turbine blades

Lightning damage to wind turbine blades is of great concern to wind power installations. We investigate various issues arising from lightning damage and assess the causes through actual lightning observations as well as from high‐voltage and large‐current experiments. Although installing lightning receptors and down conductors provide a good countermeasure, blade damage can still be caused by lightning still. New techniques are needed to better protect blades from lightning surges; these may include not only better performance and layout of receptors, but also independent lightning towers and new types of blade materials. This paper provides a classification of blade damage sustained in winter lightning, ranked in severity by analyzing the many incidents of damage that have actually occurred in Japan. Moreover, a list of possible causes of damage and relative countermeasures is also presented. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Lightning activity during winter thunderstorm and leader progression in thundercloud

We have been studying lightning discharges by means of a UHF interferometer, and we show a comparison between lightning during winter thunderstorms are those during summer. The main objective of the comparison is further understanding of features of lightning during winter storms, especially of positive cloud to ground flashes. For this purpose we compare negative and positive flashes on UHF radiation and pulse density, and perform two‐dimensional mappings of UHF radiation sources. Moreover we show the three‐dimensional imaging for a cloud flash, and discuss the relationship between the altitude of leader progressions and atmospheric temperature profiles as a function of height. We also show the estimated velocity of leader progressions and find no discrepancy with the earlier results obtained by Proctor. © 2000 Scripta Technica, Electr Eng Jpn, 133(4): 71–78, 2000     

Observation of lightning by means of time-of-arrival type lightning location system

LPATS—a lightning location system of time-of-arrival type—was installed in the middle of the Japanese island of Honshu by Tokyo Electric Power Co. in 1990. This system is LPATS Version III (LPATS III), which is the most widely used version of LPATS in the world, although there have been few reports on its operating characteristics. In order to utilize the outputs of this system to investigate lightning parameters, it is indispensable to identify its operating characteristics. The system was calibrated, and the observed distributions of the lightning current amplitude were analyzed and compared with previous reports. The results reveal that this system identifies negative return strokes in summer largely correctly, but in summer, it misinterprets many electric field pulses, originating from cloud discharges, as small positive return strokes. This result also suggests the strong dependence of the number of electric field pulses, associated with cloud discharges, on the polarity of the pulses. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 9–15, 1997     

Direct measurement of lightning current through a wind turbine generator structure

The development of a wind turbine generator system in Japan is regarded as a promising source of clean energy, and its popularization is rapidly increasing. In Japan, there are many wind turbine generator systems installed on the Sea of Japan coast, with large wind capacity. However, since the Sea of Japan coast is a region with abundant winter lightning, a phenomenon peculiar to Japan, the wind turbine generator systems are subject to damage from winter lightning. Thus, it is important to observe the lightning currents striking wind turbine generator systems in order to provide lightning protection. The authors therefore installed currents sensors (Rogowski coils) on wind turbine generators installed in Hokkaido and Kagoshima Prefectures, and performed waveform observation of lightning stroke current in the winter of 2002 and the summer of 2003. These observations yielded a few current waveforms for lightning striking wind turbine generators. This paper describes the investigation and presents the observation results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 40– 47, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20250     

Distribution arrester outages caused by lightning backflow current flowing from customer's facility into power distribution lines

Direct lightning strokes are considered to be a main cause of damage to surge arresters on power distribution lines. Recently, lightning performance of distribution lines has been observed using still cameras, and lightning‐caused distribution outages on hilltop areas on the coast of the Sea of Japan have been investigated. This research has shown a possibility that lightning backflow current flowing from customer facilities into distribution lines causes damage to surge arresters on the distribution lines. We have investigated the lightning backflow current flowing from customer facilities into distribution lines as a cause of damage to surge arresters. The main results are as follows: (1) The electric charge of the backflow current flowing into distribution lines is more than 60% of that of the lightning stroke current. (2) If the grounding resistance of the customer's facility is not low, the failure rates of a surge arrester caused by backflow current due to winter lightning is more than 90% of that caused by direct lightning strokes. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 9–20, 1999     

Characteristics of mesospheric sprites in the Hokuriku area and their causative lightning discharges

Mesospheric optical phenomena (including sprites) are becoming an interesting subject from the standpoint of atmosphere–ionosphere coupling. This paper deals with our observation of sprites associated with winter thunderstorms in the Hokuriku area and we show the characteristics of those sprites and their parent lightning discharges. Although the scale of Japanese lightning in winter is very small compared with the MCS (Mesoscale Convective System) for the summer continental lightning, the essential quantities (polarity, charge transfer, and so on) are found to be nearly the same as those for the MCS. However, an additional factor might be required, such as the self‐organization of the lightning. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 9–17, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20178     

Lightning occurrence characteristics in Japan for 17 years: observation results with lightning location systems of electric power utilities from 1992 to 2008

We summarize the lightning data for 17 years from 1992 to 2008 obtained with lightning location systems of nine electric power utilities in Japan and analyze them. The observed annual number of lightning flashes of which the current is more than 10 kA is 400 000–800 000 and the 50% value of the cumulative distribution of lightning peak currents is about 23 kA in recent times. The variation of lightning occurrence characteristics by areas, seasons, and so on, is clarified. Comparison of the obtained data with those obtained by another lightning location system is also made. The relationship between lightning occurrence and climate is discussed. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Rocket-triggered lightning experiments on zinc oxide arresters and their applications to power transmission lines

In measurements of rocket-triggered lightning current and voltage performed between 1986 and 1995 on the mountain top of Okushishiku in the Kanazawa area, the authors succeeded in artificially inducing winter lightning to arresters. Using the data obtained from those measurements, we analyzed the energy absorption characteristics of surge arresters, such as are installed on every transmission line tower for three phrases, by EMTP. The energy withstand capability of an individual arrester was verified to be approximately the same as the expected value. The analysis results for the energy share of each arrester connected in parallel showed that the usual light duty arresters installed on every tower have the possibility to be able to absorb extreme winter lightning energy even if the lightning hits the power line directly. © 1998 Scripta Technica. Electr Eng Jpn, 122(4): 25–33, 1998     

Winter lightning on Japan Sea coast-lightning striking frequency totall structures

The nature of lightning strikes on tall structures on the coast of the Japan Sea in winter has been observed with automatically triggered camera and current measurements. It is shown that the frequency of winter lightning striking tall structures is much higher than that of summer lightning and it increases proportionally to the height of structures. Sometimes lightning strikes several tall structures simultaneously. Statistics of the striking frequency, striking angle, and the leader length of the lightning discharge are presented     

适用于高土壤电阻率地区的220/110kV输电线路塔型研究

雷电故障是220/110 kV高压输电线路的主要故障型式,特别在高土壤电阻率地区体现为雷电反击故障。结合国家电网公司提出的输电线路典型设计思想,分析了高压输电线路的5种典型塔型结构,认为酒杯塔和猫头塔是承受线路反击故障的主体。选择220 kV同高度的典型酒杯塔和猫头塔建立仿真模型,采用ATP/EMTP的标准反击计算方法进行耐雷水平和反击跳闸率的计算。结果表明,在取冲击接地电阻为25Ω条件下,酒杯塔的反击耐雷性能稍好于同等参数的猫头塔。     

基于雷电定位系统的浙江电网线路雷击跳闸率评估

通过雷电定位系统观测的基础数据,评估浙江电网110～220 kV线路的雷击跳闸率,探讨传统雷击跳闸率算法的缺点,提出了算法改进的建议.     

北郊站220 kV黄北线雷击故障分析

分析了220kV黄北线雷击造成变电站电流互感器（TA）相间短路的原因,强调在多雷的广东地区必须采取措施,防止连续雷击形成的侵入波对变电站设备造成危害,提出了反事故措施,并就简单实用的间隙保护方式提出了研究建议。     

Estimation of the temperature rise in cylindrical conductors subjected to heavy 10/350 μs lightning current impulses

Lightning is a very high-energy phenomenon, which can pose serious dangers for human beings and the environment. Although much progress has been made in the area of lightning protection, there are still many cases of fires caused by lightning and power and telecommunication system outages. We have carried out an experimental and mathematical investigation into the temperature rise in cylindrical conductors subjected to heavy 10/350 μs lightning current impulses. The temperature rise measurements took place in one of the most reliable laboratories in Europe (BET, Menden, in Germany). The proposed mathematical models used to estimate the temperature rise in cylindrical conductors assumed both a uniform and non-uniform current density distribution by taking into account the transient skin effect. In addition, verification of the mathematical results were studied. Suggestions for further investigations are also provided. The experimental results are consistent with the results from the mathematical models. It is convincingly shown that copper conductors can be influenced by the transient skin effect. The additional temperature rise however, caused by the transient skin effect, is minimal, and can be neglected.