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.     

Characteristics of Winter Lightning Threatening Wind Turbines in Coastal Area of the Sea of Japan

Wind turbines on the coast of the Sea of Japan have been damaged by lightning in winter. This is due to the frequent occurrence of upward lightning from wind turbines in winter. Occurrence of upward lightning proves to be closely related to the temperature distribution at high altitudes. In this paper, the correlation between lightning hits of wind turbines and the height of the—10 ^°C layer is analyzed. When an upward lightning hits a wind turbine in winter, the height of the—10 ^°C layer is lower than 2000 m in most cases. Moreover, winter lightning is classified into two types, namely, the storm type and the inactive type, and it is found that the parameters of lightning currents observed by LLS differ depending on the type of lightning storm. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(2): 44–50, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22357     

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     

基于雷电记录与行波数据的雷击故障测距结果优化方法

针对雷击故障参考点定位不准确,导致测距结果可能与雷击故障发生的实际距离相差较大的问题,结合雷电记录与行波数据,从雷击故障参考点定位角度着手,进行雷击故障测距结果优化研究。首先获取相关雷电记录和行波数据,然后计算待分析故障特征点,并利用雷击故障历史数据、非雷击故障历史数据、雷电定位系统历史数据,构建(Δx,Δt,ΔP)三维坐标系,划分雷击故障识别域和非雷击故障识别域,判断待分析故障特征点是否落入雷击故障识别域当中,确定雷击故障参考点,最后利用行波测距方法得出雷击故障精确位置。结果表明,与基于雷电记录或基于行波数据的2种单一测距方法相比,该方法测距结果更接近实际值,由此可知,雷击故障测距结果得到优化,提高了测距精度。     

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.     

Frequency of Upward Lightning Hits to Wind Turbines in Winter

In recent years, frequent damage to wind turbines by winter lightning has been reported in the region along the Sea of Japan. It is a serious finding that lightning hits concentrate on wind turbines in this region. The authors investigated the increase rate of the frequency of lightning hits on wind turbines due to wind turbine construction by using LLS (lightning location system) data. As a result, an experimental formula to estimate the increase rate of the frequency of lightning hits on wind turbines as a function of parameters related to the construction conditions, namely the height of wind turbines, the height above sea level, and the latitude, is proposed.     

粤港澳大湾区雷电移动轨迹统计规律与潜在应用

雷暴移动轨迹直接取决于雷暴云团的移动。雷暴作为一种气象现象,其空间移动在天气系统的物理机制下,可能具有特定的规律。利用粤港澳大湾区雷电数据,进行雷电的时域分布特征和移动轨迹统计规律的挖掘分析。发现雷电日雷电数量服从Burr分布,时域上呈高度不均匀分布,50个雷电最多日雷电数量占到10 a雷电总数的一半以上。强雷暴日的雷电移动轨迹具有明显的规律特性。雷电最多的40个雷电日中,分别有20和15个雷暴的移动轨迹是从西北向东南或由东北向西南。结合气象领域研究,分析指出大湾区的东北石湖风和西北石湖风是造成雷电移动统计规律的气象学机理。在此基础上,结合输电线路在线监测系统讨论了雷电移动轨迹统计规律的潜在应用。     

Investigation of lightning tripouts on 150‐kV transmission lines in West Sumatra in Indonesia

Lightning activity in Indonesia is very high, and the ratio of lightning tripouts of the transmission line is also very high, reaching 66%. The results of our investigation show that a positive correlation exists between the number of lightning tripouts on a 150‐kV transmission line and the tower‐footing resistance and that the main cause of the tripouts is the back‐flashover. Moreover, it turns out that the flashover at the lower arm increases in case of high tower‐footing resistance. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

惠州地区雷电参数统计分析

雷电定位系统在输电线路雷击故障查询中得到了广泛地应用,是研究雷电的先进手段。根据广东省雷电定位系统1999-2007年间积累的数据,利用ArcGIS软件,从整个广东省的雷电数据中筛选出惠州地区的数据,对该地区落雷次数、雷暴日、雷电流幅值等雷电参数进行统计分析,分析雷电参数随时间变化以及各行政区域之间的差异,建议提高惠州地区防雷设计标准,加强现有线路的防雷改造。     

Influence of Grounding Resistance Connecting to Surge Arrester on Effectiveness of Lightning Protection Caused by Direct Hit for Power Distribution Lines

In Japan, the grounding resistance of surge arresters (Arrs) for the lightning protection of power distribution lines is generally maintained below 30 Ω. Therefore, electric power companies have been spending large amounts of money on the construction and maintenance of low grounding resistances. In this paper, the influence of grounding resistance on lightning protection measures for power distribution lines with both a ground wire (GW) and Arrs is investigated by EMTP analysis and experiments. These results showed that even if the grounding resistance of Arrs becomes high, the effectiveness of lightning protection is hardly decreased. The results also indicated that it is more important for constructing a rational lightning protection system to install a large number of lightning protection devices on power distribution lines than to lower the grounding resistance of Arrs. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(3): 10–22, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21280     

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     

Lightning protection of overhead power distribution lines

There are two major protective methods against lightning outages on overhead distribution lines. One is by use of surge arresters and the other is by an overhead ground wire. Surge arresters have rather constant effect regardless of the type of lightning outage causes. On the other hand, the effect of an overhead ground wire is quite different against the two major causes: direct lightning hit and induced overvoltages. This paper shows how to design lightning protection for overhead power distribution lines taking these characteristics into account. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

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     

多导体配电线路感应雷过电压分析

为分析多导体架空线负载感应雷过电压及架空地线屏蔽特性,利用傅里叶变换计算雷电流的频谱分布,根据求多导体传输线负载响应的BLT方程,在频域内求其外电磁场激励下的电报方程,计算多导体配电线路感应雷过电压的频域响应,再根据傅里叶反变换求得负载端的暂态响应。配电线路感应雷过电压特性及架空地线屏蔽作用的分析结果表明,线路垂直排列时,感应雷在负载端引起的差模干扰较大,大地电导率越小架空地线的屏蔽作用越好。     

输电线路雷电活动时空分布特征的数据挖掘

为解决目前大量的雷电观测数据没有在防雷工作中得到很好的利用,需寻找合适方法对其进行全面整理的问题,利用已在诸多行业包括电力行业中得到应用的数据挖掘技术分析处理了某地区两条线路上一年观测所获得的40893条雷电数据。现有雷电数据多是二维观测数据,利用GIS软件获得了地闪点的高程属性以分析雷电的空间分布;使用基于数据挖掘技术的DataCruncher软件中的分类分析功能针对雷电数据建立数据分类模型从而得到了雷电随时间变化的月分布、日分布趋势以及在二维空间和高度上的分布特征。该方法与传统统计方法得到的结果一致,且相比传统统计方法,其在分析数据时更迅速准确。     

雷电流作用下铁件剩磁量的规律分析

剩磁法是一种雷灾鉴定中判定是否发生雷击事故的方法,但标准中只给出判定的参考剩磁数据,其数据通用性有待斟酌。为了探究铁件剩磁量的规律,通过模拟雷电流的发生,选取一定的试样进行冲击测试后测量剩磁,得出了影响剩磁的主要因素有铁件材质、尺寸、所在位置、测量位置、雷电流大小、冲击条件、次数等,并得出0.5~1.5 mT区间的数据同样可以作为判定依据。而当冲击次数为5次以后,由于铁件的剩磁累积效应,铁件的剩磁量逐步达到饱和。得到的结论为雷灾鉴定工作提供了一定的理论基础。     

A field study of lightning overvoltages in low‐voltage distribution lines

The number of home electric appliances, such as personal computers and telephones, has been rapidly increasing. Lightning damage to these home electric appliances has a great impact on a highly sophisticated information society. There are cases in which lightning overvoltages in low‐voltage distribution lines cause malfunctions in them, even though they are equipped with surge protective devices to protect against lightning overvoltages. Therefore, for lightning protection of low‐voltage equipment including home electric appliances, it is important to understand the phenomenon of lightning overvoltages in low‐voltage power distribution lines. However, many aspects of this problem are not entirely clear, in particular how they are generated. The Tokyo Electric Power Company carried out lightning observations on low‐voltage distribution lines. The observation results provide a statistical distribution of lightning overvoltages in low‐voltage distribution lines. A mechanism for generating lightning overvoltages in low‐voltage distribution lines is inferred from the observed waveforms and facilities data. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 12–21, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21299     

Evaluation of lightning fault rate of EHV transmission line based on lightning parameters derived from electromagnetic observation

Cloud-to-ground lightning flashes in the Niigata area in Japan have been observed for a few years by a magnetic direction-finder network. Data obtained so far are analyzed carefully taking into account the operating characteristics of the system. As a result, frequency distributions of return-stroke current for each polarity are produced, and their seasonal variations and the occurrence probabilities of high current exceeding 200 kA are clarified. Based on the estimated current distributions, back-flashover rates of 500-kV 2 cct transmission lines are calculated. It is known that the back-flashover caused by downward flashes can account for most of the line outages in the summer for both single- and multiple-line faults. However, this mechanism cannot explain the high outage rate in the winter experienced in the winter thunderstorm area in the late 1970s. In spite of the low lightning flash density in the winter, the multiple-line fault rate in the winter caused by back-flashovers is predicted to be comparable to that in the summer, because of the seasonal variation of the frequency distributions of return-stroke current.     

3种地形上高杆塔雷击次数规律的研究

为了更有效地研究电力线路杆塔在不同地形下防雷性能的差异性,笔者针对珠三角地区中的杆塔在3种不同地形下受雷击次数分布差异性问题进行分析。首先建立区域雷击统计模型,研究统计区域雷击次数的方法。然后基于雷电定位系统,对珠三角地区三种地形上10年落雷情况进行统计分析,得出电力杆塔在山区受雷击次数略高于平原建筑区,平原建筑区上的杆塔虽受高层建筑屏蔽保护作用,不易受雷击,但杆塔所处区域受雷击次数高于平原植被区。经过统计得出平原建筑落雷次数增长率明显增大,而山区与平原植被区落雷次数增长率呈下降趋势。最后利用电场仿真软件仿真坐落在3种地形上杆塔周围的电场分布趋势,验证统计出区域雷击次数规律的合理性。     

Substation outage rate prediction method based on lightning characteristics

A unique method of predicting lightning outage rates for substations, taking into account statistics‐based lightning characteristics, has been developed. The proposed method features the application of a combination of two processes: a high‐accuracy lightning surge analysis applying the electromagnetic transient program (EMTP) and a statistical data analysis using a general‐purpose spreadsheet software. By employing an original tool applying the proposed prediction method, which is installed in a personal computer, an optimal lightning protection for substations can be designed. In this paper, several analysis models are proposed for lightning characteristics including lightning surge. The validity of the proposed method was confirmed by comparing the transmission line outage rates derived by the models with the outage data gained during actual observations. It was found that the predicted lightning outage rates for 500‐kV substations were relatively low, and this finding revealed that it is possible to decrease the impulse withstand voltage level (LIWV). © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(2): 64–75, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10300