Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627408
K. Ishimoto, F. Tossani, F. Napolitano, A. Borghetti, C. Nucci
In medium-voltage distribution lines, lightning outages associated with indirect strokes are less frequent if these lines are equipped with a grounded shield wire and surge arresters are installed at close intervals. Thus, for this case, the lightning performance is mainly associated with the line response due to direct events. Recent analysis concerning medium voltage line equipped with a shield wire shows that the electromagnetic pulse radiated from the channel may enhance the overvoltage across insulators during direct strikes. This paper extends the analysis to lines over lossy soils, assuming different values of ground conductivity. The results indicate that the effect of the electromagnetic pulse needs indeed to be considered for an accurate lightning performance assessment of distribution lines with shield wire. On the one hand, the voltages across insulators increase as the soil conductivity decreases; on the other hand, it is shown that for direct strikes the difference between the voltage amplitudes calculated considering or not the LEMP contribution increases with the ground conductivity. Thus, appropriate modelling and relevant calculation tools availability is fundamental for the problem of interest.
{"title":"Influence of the Electromagnetic Pulse on the Overvoltages Due to Direct Lightning to Lines over Soils with Different Ground Conductivity","authors":"K. Ishimoto, F. Tossani, F. Napolitano, A. Borghetti, C. Nucci","doi":"10.1109/ICLPandSIPDA54065.2021.9627408","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627408","url":null,"abstract":"In medium-voltage distribution lines, lightning outages associated with indirect strokes are less frequent if these lines are equipped with a grounded shield wire and surge arresters are installed at close intervals. Thus, for this case, the lightning performance is mainly associated with the line response due to direct events. Recent analysis concerning medium voltage line equipped with a shield wire shows that the electromagnetic pulse radiated from the channel may enhance the overvoltage across insulators during direct strikes. This paper extends the analysis to lines over lossy soils, assuming different values of ground conductivity. The results indicate that the effect of the electromagnetic pulse needs indeed to be considered for an accurate lightning performance assessment of distribution lines with shield wire. On the one hand, the voltages across insulators increase as the soil conductivity decreases; on the other hand, it is shown that for direct strikes the difference between the voltage amplitudes calculated considering or not the LEMP contribution increases with the ground conductivity. Thus, appropriate modelling and relevant calculation tools availability is fundamental for the problem of interest.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73917073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627459
Xiangen Zhao, Juhyeong Lee, Junjia He
The space stem has raised wide and long-standing concerns from researchers around the world since it was found in natural lightning first, while needs to be further studied. This paper aims at providing details of space stem morphology and development in both negative and positive sparks in a 1.27 m point-plane gap in the laboratory, using a high-speed Schlieren system. It is found that the stem areas captured in the traditional high-speed images were overestimated and the Schlieren images were preferable for the detailed observation. There was an evidence of possible (but small) positive space stem. By comparison, the negative space stem was much more obvious than the positive space stem. The average length of negative space stem was about 1.83 mm. During the step process, the space stem propagated both bidirectionally and unidirectionally. The positive portion developed at an average speed of 1.19×103m/s. In only one case for bidirectional develoment, the negative portion had a faster speed than the positive portion, which means that negative portion develops slower than the positive one as reported in other papers may be not always right. In addition, two scenarios were found for the connection between the space stem and the main channel, i.e., one to the channel tip directly, and the other to the channel side.
{"title":"High-Speed Schlieren Photographic Observations of Space Stems in Negative and Positive Sparks","authors":"Xiangen Zhao, Juhyeong Lee, Junjia He","doi":"10.1109/ICLPandSIPDA54065.2021.9627459","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627459","url":null,"abstract":"The space stem has raised wide and long-standing concerns from researchers around the world since it was found in natural lightning first, while needs to be further studied. This paper aims at providing details of space stem morphology and development in both negative and positive sparks in a 1.27 m point-plane gap in the laboratory, using a high-speed Schlieren system. It is found that the stem areas captured in the traditional high-speed images were overestimated and the Schlieren images were preferable for the detailed observation. There was an evidence of possible (but small) positive space stem. By comparison, the negative space stem was much more obvious than the positive space stem. The average length of negative space stem was about 1.83 mm. During the step process, the space stem propagated both bidirectionally and unidirectionally. The positive portion developed at an average speed of 1.19×103m/s. In only one case for bidirectional develoment, the negative portion had a faster speed than the positive portion, which means that negative portion develops slower than the positive one as reported in other papers may be not always right. In addition, two scenarios were found for the connection between the space stem and the main channel, i.e., one to the channel tip directly, and the other to the channel side.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81486566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627333
J. Cristancho, J. Rodríguez, C. Rivera, F. Roman, A. Piantini, M. Shigihara, C. Kodaira
Lightning strokes can hit buildings, structures, living beings, and the ground, jeopardizing the integrity and health of people and animals and causing damages to trees and equipment. Some outdoor human activities in backcountry places require adequate lightning protection systems (LPS) to reduce the risk of damage to health. Preliminary research has shown that the use of electroconductive fabrics could serve as part of lightweight LPSs. In this research work we investigate the behavior of samples of a rip-stop electroconductive fabric submitted to lightning impulse currents with amplitudes in the range 5 kA to 20 kA and 8/20 µs waveshape. Both the voltage and current signatures were recorded. The results show that there is more than one mechanism of electric conduction in the electroconductive fabric, allowing it to endure lightning currents.
{"title":"Behavior of an Electroconductive Rip-stop Fabric under 8/20 µs Lightning Current: Preliminary Results","authors":"J. Cristancho, J. Rodríguez, C. Rivera, F. Roman, A. Piantini, M. Shigihara, C. Kodaira","doi":"10.1109/ICLPandSIPDA54065.2021.9627333","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627333","url":null,"abstract":"Lightning strokes can hit buildings, structures, living beings, and the ground, jeopardizing the integrity and health of people and animals and causing damages to trees and equipment. Some outdoor human activities in backcountry places require adequate lightning protection systems (LPS) to reduce the risk of damage to health. Preliminary research has shown that the use of electroconductive fabrics could serve as part of lightweight LPSs. In this research work we investigate the behavior of samples of a rip-stop electroconductive fabric submitted to lightning impulse currents with amplitudes in the range 5 kA to 20 kA and 8/20 µs waveshape. Both the voltage and current signatures were recorded. The results show that there is more than one mechanism of electric conduction in the electroconductive fabric, allowing it to endure lightning currents.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80070201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627477
F. H. Silveira, Frederico S. Almeida, S. Visacro
The effect of first return stroke current distributions of tropical and temperate regions on the assessment of backflashover occurrence of transmission lines is analyzed by means of computational simulations. Current parameters and associated distributions derived from the measurements performed at Morro do Cachimbo station (MCS), Brazil, that comprise 51 negative cloud-to-ground flashes and median first stroke peak current of 43 kA are considered. The results were compared with those obtained from the application of current parameters derived in a temperate region at Mount San Salvatore station (MSS), Switzerland and the cumulative peak current of first strokes recommended by IEEE Std 1243. Sensitivity analyses were developed considering typical configurations of 138-kV and 230-kV transmission lines in a wide range of tower-footing grounding impedance and representative first stroke current waveform. The obtained results revealed about 44%-to-54% larger and 54%-to-28% lower backflashover probability related to the application of MCS peak current distribution data, in the 20-to-40-Ω tower-footing grounding impedance range, for the 138-kV and 230-kV transmission lines, respectively.
采用计算模拟的方法，分析了热带和温带地区输电线路一次回冲电流分布对反闪络发生评估的影响。考虑了在巴西Morro do Cachimbo站(MCS)进行的测量得出的电流参数和相关分布，包括51次负云对地闪光和43 kA的中位第一冲程峰值电流。将所得结果与瑞士Mount San Salvatore站(MSS)温带地区电流参数的应用结果以及IEEE Std 1243推荐的首冲程累积峰值电流进行了比较。考虑了138kv和230kv输电线路的典型配置，在大范围的塔基接地阻抗和具有代表性的首冲程电流波形下，进行了灵敏度分析。结果表明，在20 ~ 40-Ω塔基接地阻抗范围内，应用MCS峰值电流分布数据，138-kV和230-kV输电线路的反闪络概率分别增大44% ~ 54%和54% ~ 28%。
{"title":"Influence of First Return Stroke Current Distributions of Tropical and Temperate Regions on the Assessment of Backflashover Occurrence of Transmission Lines","authors":"F. H. Silveira, Frederico S. Almeida, S. Visacro","doi":"10.1109/ICLPandSIPDA54065.2021.9627477","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627477","url":null,"abstract":"The effect of first return stroke current distributions of tropical and temperate regions on the assessment of backflashover occurrence of transmission lines is analyzed by means of computational simulations. Current parameters and associated distributions derived from the measurements performed at Morro do Cachimbo station (MCS), Brazil, that comprise 51 negative cloud-to-ground flashes and median first stroke peak current of 43 kA are considered. The results were compared with those obtained from the application of current parameters derived in a temperate region at Mount San Salvatore station (MSS), Switzerland and the cumulative peak current of first strokes recommended by IEEE Std 1243. Sensitivity analyses were developed considering typical configurations of 138-kV and 230-kV transmission lines in a wide range of tower-footing grounding impedance and representative first stroke current waveform. The obtained results revealed about 44%-to-54% larger and 54%-to-28% lower backflashover probability related to the application of MCS peak current distribution data, in the 20-to-40-Ω tower-footing grounding impedance range, for the 138-kV and 230-kV transmission lines, respectively.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80411436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627443
Jaimis Sajid Leon Colqui, Luis Carlos Timaná, Sérgio Kurokawa, Anderson Ricardo Justo de Araújo, J. Pissolato Filho
The purpose of this paper is to investigate the performance of the Frequency-Dependent Lumped Parameter Model (FD-LPM) to adequately represent two distinct overhead transmission lines (OHTLs) subjected to different lightning currents. Frequency-Dependent Lumped Parameter Model (FD-LPM) takes into account the Skin and ground-return effects required to properly represent an OHTL and to compute the electromagnetic transients in power system. The FD-LPM is ruled by state equations in which the longitudinal parameters can be adjusted by a rational function using the Vector Fitting Technique and extended to any Electromagnetic Transient (EMT)-type simulators First, longitudinal impedances of these OHTLs are fitted into a rational function in residue-pole form which are incorporated in the ATPDraw software by the component LIB. Then, time domain responses due to lightning currents are computed under different scenarios. The FD-LPM was employed to represent short lines subjected to lightning strikes whose time domain responses were computed to different step sizes. Furthermore, results were compared with the JMarti's model for and those computed by Numerical Laplace Transform (NLT). Numerical results demonstrate that transient responses obtained with FD-LPM under small step size present a good agreement with those computed by NLT, which are assumed as reference responses.
{"title":"Lightning Current on the Frequency-Dependent Lumped Parameter Model Representing Short Transmission Lines","authors":"Jaimis Sajid Leon Colqui, Luis Carlos Timaná, Sérgio Kurokawa, Anderson Ricardo Justo de Araújo, J. Pissolato Filho","doi":"10.1109/ICLPandSIPDA54065.2021.9627443","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627443","url":null,"abstract":"The purpose of this paper is to investigate the performance of the Frequency-Dependent Lumped Parameter Model (FD-LPM) to adequately represent two distinct overhead transmission lines (OHTLs) subjected to different lightning currents. Frequency-Dependent Lumped Parameter Model (FD-LPM) takes into account the Skin and ground-return effects required to properly represent an OHTL and to compute the electromagnetic transients in power system. The FD-LPM is ruled by state equations in which the longitudinal parameters can be adjusted by a rational function using the Vector Fitting Technique and extended to any Electromagnetic Transient (EMT)-type simulators First, longitudinal impedances of these OHTLs are fitted into a rational function in residue-pole form which are incorporated in the ATPDraw software by the component LIB. Then, time domain responses due to lightning currents are computed under different scenarios. The FD-LPM was employed to represent short lines subjected to lightning strikes whose time domain responses were computed to different step sizes. Furthermore, results were compared with the JMarti's model for and those computed by Numerical Laplace Transform (NLT). Numerical results demonstrate that transient responses obtained with FD-LPM under small step size present a good agreement with those computed by NLT, which are assumed as reference responses.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90568072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627497
Fengjiao Liu, Ming Xue, Defeng Xue, Yao Tang, Qiuyan He
Based on the application of lightning data, this paper conducted multifaceted researches to provide more reference ideas for selection of lightning risk assessment, early warning and division factor. Based on principles of weather science and mathematical statistics, this paper presents selection of lightning data factors, factor optimization, variable combination and risk classification method and makes a comparative analysis of lightning data factors and relative standards. The results show that the data processing and optimization of lightning factor has a significant indication of the lightning risk and combination factor of lightning factor is better than single factor and combination of four factors is the best and most stable. According to method in this paper, it is verified that the strong thunder factor which 25kA lightning current parameters choose according to GB50057 standard has better indication function to high risk level of lightning and distribution of lightning variable risk level and superposition diagram of lightning disaster of Huaihua are drawn to conclude that most areas where number of thunder disaster is concentrated are the areas which have higher risk level of lightning variables.
{"title":"Research and application model of disaster risk optimization based on lightning data","authors":"Fengjiao Liu, Ming Xue, Defeng Xue, Yao Tang, Qiuyan He","doi":"10.1109/ICLPandSIPDA54065.2021.9627497","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627497","url":null,"abstract":"Based on the application of lightning data, this paper conducted multifaceted researches to provide more reference ideas for selection of lightning risk assessment, early warning and division factor. Based on principles of weather science and mathematical statistics, this paper presents selection of lightning data factors, factor optimization, variable combination and risk classification method and makes a comparative analysis of lightning data factors and relative standards. The results show that the data processing and optimization of lightning factor has a significant indication of the lightning risk and combination factor of lightning factor is better than single factor and combination of four factors is the best and most stable. According to method in this paper, it is verified that the strong thunder factor which 25kA lightning current parameters choose according to GB50057 standard has better indication function to high risk level of lightning and distribution of lightning variable risk level and superposition diagram of lightning disaster of Huaihua are drawn to conclude that most areas where number of thunder disaster is concentrated are the areas which have higher risk level of lightning variables.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91123416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627446
D. Mestriner, M. Brignone, R. Procopio, F. Rachidi, A. Piantini
Dealing with realistic networks, the solution of lightning electromagnetic field coupling to transmission lines is generally obtained through a Finite-Difference Time-Domain (FDTD) algorithm interfaced with an electromagnetic simulator. As well known, the stability of the FDTD scheme is determined by the Courant stability condition. In this contribution, it is shown that a second stability condition that limits the ratio between the space step and the line length appears when spatial extrapolation is used to obtain the values of the currents at the line extremities to be interfaced with a transient electromagnetic simulator. Finally, this work aims at solving the aforementioned problem by using a different approach to obtain the currents at the line extremities.
{"title":"A Method for the Improvement of the Stability in FDTD-Based Numerical Codes Evaluating Lightning-Induced Voltages","authors":"D. Mestriner, M. Brignone, R. Procopio, F. Rachidi, A. Piantini","doi":"10.1109/ICLPandSIPDA54065.2021.9627446","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627446","url":null,"abstract":"Dealing with realistic networks, the solution of lightning electromagnetic field coupling to transmission lines is generally obtained through a Finite-Difference Time-Domain (FDTD) algorithm interfaced with an electromagnetic simulator. As well known, the stability of the FDTD scheme is determined by the Courant stability condition. In this contribution, it is shown that a second stability condition that limits the ratio between the space step and the line length appears when spatial extrapolation is used to obtain the values of the currents at the line extremities to be interfaced with a transient electromagnetic simulator. Finally, this work aims at solving the aforementioned problem by using a different approach to obtain the currents at the line extremities.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86993096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627471
F. Grange, Diego Pereira Botelho, S. Journet, S. Fortin, F. Dawalibi
Analysis of transmission lines backflashovers is of particular importance for the service quality. The tower surge impedance is a key parameter for the prediction and estimation of backflashovers. In this paper we introduce a new multi-region soil model to take into account soil model variations along a transmission line while using a global full-wave modelling approach. This new capability focuses on the transient behavior of the whole system to assess backflashover occurrences along the transmission line.
{"title":"Multi-Region Soil Model for Transmission Line Backflashover Analysis","authors":"F. Grange, Diego Pereira Botelho, S. Journet, S. Fortin, F. Dawalibi","doi":"10.1109/ICLPandSIPDA54065.2021.9627471","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627471","url":null,"abstract":"Analysis of transmission lines backflashovers is of particular importance for the service quality. The tower surge impedance is a key parameter for the prediction and estimation of backflashovers. In this paper we introduce a new multi-region soil model to take into account soil model variations along a transmission line while using a global full-wave modelling approach. This new capability focuses on the transient behavior of the whole system to assess backflashover occurrences along the transmission line.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84477310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627372
Gang Liu, Xiaolei Wang, H. Cai, M. Liao, Shangmao Hu, Yu Liu
The initiation and propagation characteristics of recoil leader (RL) activity during the long continuing current (CC) stage of one positive cloud-to-ground (CG) lightning flash have been investigated based on high-speed video observations. The main findings are as follows: Abundant RL activity mainly occurs along three previously formed positive leader channels. Some RL events show apparent bidirectional propagation, and the two-dimensional (2-D) average propagation speed ranges from 8.10x105 m/s to 5.99x106 m/s for both ends, mainly in the order of 106 m/s. RL activity shows some interesting characteristics that the branched leader tips formed on its positive end can develop alternately during one development process and RL initiates next time can follow either path of these branches; after RL channel has been decayed for some time, RL can further develop and reilluminate on its positive end with the branched leader tips; RL propagation upon connection to the active positive discharge leader can cause an M-component on the background CC current, with great luminosity and a rather long duration.
基于高速视频观测，研究了一次正云对地闪电长持续电流(CC)阶段反冲前导(RL)活动的产生和传播特性。主要发现如下:丰富的RL活动主要发生在三个先前形成的积极领导通道上。部分RL事件呈现明显的双向传播，两端二维平均传播速度在8.10 × 105 m/s ~ 5.99 × 106 m/s之间，以106 m/s量级为主。RL活动表现出一些有趣的特征，即在一个发育过程中，在其正端形成的分支领导提示可以交替发展，下一次启动RL可以遵循这些分支的任何一条路径;在RL通道衰减一段时间后，RL可以在其正端进一步发育并通过分支的先导尖重新照亮;RL在连接有源正放电引线后传播，在背景CC电流上产生m分量，亮度大，持续时间长。
{"title":"Optical Characteristics of Recoil Leader Activity in one Positive Cloud-to-ground Lightning Flash","authors":"Gang Liu, Xiaolei Wang, H. Cai, M. Liao, Shangmao Hu, Yu Liu","doi":"10.1109/ICLPandSIPDA54065.2021.9627372","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627372","url":null,"abstract":"The initiation and propagation characteristics of recoil leader (RL) activity during the long continuing current (CC) stage of one positive cloud-to-ground (CG) lightning flash have been investigated based on high-speed video observations. The main findings are as follows: Abundant RL activity mainly occurs along three previously formed positive leader channels. Some RL events show apparent bidirectional propagation, and the two-dimensional (2-D) average propagation speed ranges from 8.10x105 m/s to 5.99x106 m/s for both ends, mainly in the order of 106 m/s. RL activity shows some interesting characteristics that the branched leader tips formed on its positive end can develop alternately during one development process and RL initiates next time can follow either path of these branches; after RL channel has been decayed for some time, RL can further develop and reilluminate on its positive end with the branched leader tips; RL propagation upon connection to the active positive discharge leader can cause an M-component on the background CC current, with great luminosity and a rather long duration.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85388021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-09-20DOI: 10.1109/ICLPandSIPDA54065.2021.9627411
Tomoyuki Nakano, M. Kotari, T. Ohtaka, Y. Goda, M. Iwata
This paper describes a 50 kA lightning impulse arc test to optical ground wires (OPGWs), focusing on the external appearance of the lightning impulse arc. Two types of high speed cameras were employed to observe time resolved pictures of the arc. We estimated the diameter of the arc from its shape in the observed pictures. We subsequently obtained the time variation of the current density in the arc. The estimated arc diameter was in good agreement with the values obtained from other literature, thus, the current density obtained in this study can be considered valid. We calculated an estimate of the distribution of energy input to the OPGW, as a result of electron transport.
{"title":"Estimation of Time Variation of Current Density in a 50 kA Lightning Impulse Arc using High Speed Cameras","authors":"Tomoyuki Nakano, M. Kotari, T. Ohtaka, Y. Goda, M. Iwata","doi":"10.1109/ICLPandSIPDA54065.2021.9627411","DOIUrl":"https://doi.org/10.1109/ICLPandSIPDA54065.2021.9627411","url":null,"abstract":"This paper describes a 50 kA lightning impulse arc test to optical ground wires (OPGWs), focusing on the external appearance of the lightning impulse arc. Two types of high speed cameras were employed to observe time resolved pictures of the arc. We estimated the diameter of the arc from its shape in the observed pictures. We subsequently obtained the time variation of the current density in the arc. The estimated arc diameter was in good agreement with the values obtained from other literature, thus, the current density obtained in this study can be considered valid. We calculated an estimate of the distribution of energy input to the OPGW, as a result of electron transport.","PeriodicalId":70714,"journal":{"name":"中国防雷","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76627496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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