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Lightning (APL), 2011 7th Asia-Pacific International Conference on

Date 1-4 Nov. 2011

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    Publication Year: 2011 , Page(s): 1
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  • [Front matter]

    Publication Year: 2011 , Page(s): 1 - 7
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  • Technical programme

    Publication Year: 2011 , Page(s): 1 - 21
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  • Author index

    Publication Year: 2011 , Page(s): 1 - 33
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  • Soil model's inversion calculation based on genetic algorithm

    Publication Year: 2011 , Page(s): 225 - 230
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (124 KB) |  | HTML iconHTML  

    The traditional grounding grid analysis method viewed practical inhomogeneous soil as homogeneous soil. However, when the substation grounding grid area is very large, there are a large part of fault current will flow away from the deep soil, deep soil of grounding grid has a great impact to grounding performance, so how to accurately obtain the soil layered structure model is the foundation of grounding system design and simulation calculations, can make the grounding design more reasonable, at the same time, can reduce unnecessary blindness. Through the introduction of nonlinear objective function, The paper introduce into genetic algorithms which deal with the parameters optimization for multilayer structure models of soil is excellently, A recursive method to get the exact expressions of Green's Functions in multilayer earth is resented in this paper, in the presence of Wenner measurement method. The author make use of the relationship between apparent resistivity and probe distance. By introducing nonlinear objective function, the solution of soil parameters will be transformed extremum question of objective function, combined with genetic algorithm, the horizontal layered soil model is inversed. the method can calculate the arbitrary stratified soil models. Calculations show that the method practical. View full abstract»

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  • Return stroke currents of triggered lightning in Guangdong, China

    Publication Year: 2011 , Page(s): 231 - 234
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB) |  | HTML iconHTML  

    The current measurements of 17 return strokes (RSs) produced by 6 classical triggered lightning flashes (TLFs) conducted in Guangdong, China from 2008 to 2010 were analyzed for the first time in this study. The geometric mean (GM) value of the peak value current (IPeak) is 16.59 kA, the half-peak width (tHPW) is 21.91 μs, the 10-90% risetime (t10-90%) is 0.45 μs, the 10-90% average gradient (G10-90%) is 29.61 kA μs-1, the maximum gradient (GMax) is 55.89 kA μs-1, the charge transfer in 1ms after the beginning of the return strokes (Q1ms) is 1.61 C, and the action integral in 1ms after the beginning of the return strokes (AI1ms) is 6.60×103 A2 s. The RSs in GCOELD are, on average, stronger than those reported by other authors referenced in this study. The peak value current has a general good linear relation with G10-90% (determination coefficient (R2) = 0.64), a good linear relation with GMax (R2=0.74), a strong power function relation with Q1ms (R2=0.89), and an excellent logarithmic function relation with AI1ms (R2=0.92). Additionally, the current of the initial-stage return stroke (ISRS) of an altitude TLF was analyzed and found to have small tHPW (2.12 μs), charge transfer (36.37 mC) and action integral (181.56 A2 s), but was similar to other RSs for all other parameters. After the ISRS, a number of chopped-shape pulses, attributed to the back-and-forth reflections of the ISRS current, were recorded and analyzed for their characteristics. View full abstract»

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  • On the origin of two types of current pulses observed during the initial stage of upward lightning

    Publication Year: 2011 , Page(s): 235 - 239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (273 KB) |  | HTML iconHTML  

    We analyzed high-speed video images and corresponding current records for eight upward lightning flashes initiated by the Peissenberg tower (160 m) in Germany. These flashes contained a total of 33 measurable initial stage (IS) current pulses, which are superimposed on steady IS currents. Seven IS pulses had relatively short (<; 8 μs) 10-to-90% risetimes and 26 IS pulses had relatively long (>; 8 μs) risetimes. Six (86%) of seven IS current pulses with shorter risetimes each developed in a newly-illuminated branch, and 25 (96%) of 26 IS pulses with longer risetimes occurred in already luminous (current-carrying) channels. These results support the hypothesis that longer risetimes are indicative of the M-component mode of charge transfer to ground, while shorter risetimes are associated with the leader/return stroke mode. Similar results were obtained for M-component pulses that are superimposed on continuing currents following return-stroke pulses. View full abstract»

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  • Lightning current models' characteristics based on continuous wavelet transform

    Publication Year: 2011 , Page(s): 240 - 243
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (611 KB) |  | HTML iconHTML  

    The analysis and simulation of two typical lightning current models by continuous wavelet transform (CWT) were given in the paper. The results compared with traditional Fourier transformation showed that the two-dimensional gray image obtained by CWT could get the information of time and frequency of the lightning current models' signals. Further more, the corresponding spectral characteristics of the lightning current models' signals were investigated. And theoretical basics for further analysis of lightning current models' characteristics were provided. View full abstract»

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  • Distribution of electromagnetic field for spatial diagonal lightning current

    Publication Year: 2011 , Page(s): 244 - 247
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB) |  | HTML iconHTML  

    The analysis for lightning current facing in communication system has been analyzed and discussed in literatures. But the most of them are the situations of perpendicular to the ground for the lightning current, which is not universal. In this thesis, lightning current is simplified into a model of spatial diagonal current source, and `image method' is adopted in the analysis of electromagnetic field distribution. The results show that lightning would create strong electromagnetic radiation when lightning occurs. This method provides a theoretical basis for further analysis of lightning protections. View full abstract»

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  • The number of strokes per flash measured by JLDN

    Publication Year: 2011 , Page(s): 248 - 253
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB) |  | HTML iconHTML  

    Japanese Lightning Detection Network (JLDN) operated by Franklin Japan Corporation (FJC) has been provided stroke data as our standard commercial lightning data [1]. However, it is much useful for lightning protection system designs to use flash data rather than using stroke data [2]. Therefore, this paper examines the method of conversion of stroke data into flash data and multiplicities of lightning flashes observed by JLDN. In addition to the above, we also compare our data with other nationwide lightning detection network and discuss the characteristics of flash multiplicity measured by JLDN. The FJC uses the algorithm which is different from the National Lightning Detection Network (NLDN). Therefore, we discuss the validity of the JLDN flash algorithm by comparing flash multiplicities calculated by both the JLDN flash algorithm and the NLDN one. In addition, we compare the flash multiplicities measured by JLDN with those measured by other nationwide lightning detection network and examine the network performance of JLDN regarding the flash multiplicity. View full abstract»

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  • On the concern of aged Lightning Air Terminal's capturing capability and improvement by mean of chemical treatment

    Publication Year: 2011 , Page(s): 254 - 257
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    Lightning Air Terminal (LAT) is normally a sharp-tipped rod that is used to intercept direct lightning strike to ground structures. However it was found that LAT sometimes does not function as it should be due to aging and prolonged exposure to the acidic rain. This paper presents on the studies to determine chemical compounds; Polyvinyl Acetate and Polyvinyl Alcohol that can be use to enhance LATs' capturing capability. The chemicals act as a `make-up' that helps the LAT to resist the effect of acid rain while increasing its conductivity and lightning leaders capturing capability. These findings were based on laboratory experiments. Further research has to be done on actual site testing using rocket-triggered lightning or on-situ monitoring of LATs performance. However it was found that in an environment where acidity is at pH 4, Polyvinyl Acetate is best for the LATs' performance improvement. View full abstract»

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  • Recent progress of ITU-T recommendations on lightning protection

    Publication Year: 2011 , Page(s): 258 - 262
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    This paper presents recent documents produced by ITU-T Study Group 5 about the protection of telecommunication systems against lightning. These documents are known as Recommendations and provide protection procedures for the design, construction and maintenance of telecommunication networks. After presenting a general overview of the lightning protection documents, four of them are described in detail: K. 47 (protection of lines against direct flashes), K. 46 (protection of lines against lightning induced surges), K. 56 / K. dbs (protection of radio base stations). The innovative aspects of these Recommendations are highlighted, in order to provide an overview of the advances in the art of lightning protection carried out within ITU-T SG-5. ITU-T K. 47 is currently modelling the protective effect provided by guard-wires, while ITU-T K. 46 is introducing new concepts to allow the implementation of protection based on a risk assessment approach. Finally, ITU-T K. 56 and ITU-T K. dbs provides quantitative measures to protect standard and newly developed radio-base stations against direct lightning flashes. View full abstract»

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  • Review of upward positive and bipolar lightning flashes at the Gaisberg Tower

    Publication Year: 2011 , Page(s): 263 - 267
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (345 KB) |  | HTML iconHTML  

    First instrumentation for lightning measurements at the Gaisberg Tower (GBT) has been installed in 1998. During the 10-years period from 2000-2009 a total of 652 lightning events have been recorded. Vast majority of the lightning to the GBT was upward initiated and only one record is a candidate for a downward flash when the recorded current waveform is used for discrimination between upward and downward lightning. 3% (21/652) of the flashes were bipolar and about the same number of 4% (26/652) were positive. 73% of positive and 63% of bipolar lightning was triggered by the GBT during cold season in Austria. View full abstract»

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  • Analysis of lightning characteristics in a MCS with damaging straight-line wind

    Publication Year: 2011 , Page(s): 268 - 273
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB) |  | HTML iconHTML  

    One severe thunderstorm with damaging straight-line wind occurred on 21 June 2005 in north Shandong Province. Based on the analysis of lightning activities, radar echo and cloud image, it was found that the cloud-to-ground (CG) flash rates increased rapidly at initial stage, and they were very high (about above 20 fl/5min) all along the mature stage. At the dissipating stage, positive CG flashes gradually dominated. Almost all negative CG flashes occurred in the convective precipitation regions, whereas most positive CG flashes corresponded to stratiform precipitation regions. For the advent of the peak value, the hourly flash rate lagged behind the minimum brightness temperature, and the area of cold cloud shield with temperature <;-50°C lagged behind the hourly flash rate. Gust occurred in the regions with dense CG flashes. The pulse of CG flash rate was slightly ahead of the occurrence of severe surface wind. The damaging wind was due to downburst. The maximum wind speed observed at weather station was approximate to the maximum potential speed calculated by WINDEX. View full abstract»

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  • Influence of grounding conditions on SE of shielded room in LEMP environment

    Publication Year: 2011 , Page(s): 274 - 277
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (165 KB) |  | HTML iconHTML  

    In order to analyze the influence of grounding conditions on the shielding effectiveness (SE) of shielded room, numerical simulation is done by applying parallel Finite-Difference Time-Domain (FDTD) method on the coupling problems between shielded room and lightning electromagnetic pulse (LEMP) environments. Inner coupled electromagnetic (EM) fields are calculated when the shielded room is with different grounding locations and schemes. The results indicate: (1) the farther the distance between the grounding location and the aperture, the better the SE of shielded room, the nearer the worse. (2) The SE is related to the different grounding schemes (single-point grounding and multipoint grounding). For a better SE to LEMP, shielded room should use single-point grounding. View full abstract»

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  • Study of a new Jet Stream Interrupter Gap Lightning Protection Device

    Publication Year: 2011 , Page(s): 278 - 283
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1018 KB) |  | HTML iconHTML  

    To avoid the overhead transmission lines suffering from the harm of lighting, a new type of Jet Stream Interrupter Gap Lightning Protection Device (JSGLPD) has been developed and applied, which is applied on 10Kv and 35Kv transmission lines. Improved mayr arc model is formulated to simulate the arc extinguishing capacity of by JSGLPD, when the arc is produced by Grounding short-circuit current. The velocity and working scope of jet stream is calculated with Two-dimensional N-S equation and k-ε turbulence model to get the losing coefficient of arc model, and the time coefficient is obtained though arc extinguishing experiment. Compared the simulation with waveform from oscillograph and the picture from high-speed camera in the low current arc extinguishing experiment, good agreement is found. So both the simulation and the experiment show the arc can be strongly and rapidly extinguished by JSGLPD. View full abstract»

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  • Current and close EM field of rocket-triggered lightning flashes in SHATLE 2005–2010

    Publication Year: 2011 , Page(s): 284 - 287
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (203 KB) |  | HTML iconHTML  

    Shandong Artificially Triggering Lightning Experiment (SHATLE) has been conducted continuously since the summer of 2005. During the six years from 2005 to 2010, twenty-two negative lightning flashes containing eighty-eight return strokes were successfully triggered. Channel base currents, close electromagnetic fields and high-speed camera images were obtained simultaneously for some of the strokes. Based on directly measured currents for thirty-six return strokes, the geometric mean of return stroke peak current was about 12.1 kA with a maximum of 41.6 kA and a minimum of 4.4 kA, the half peak width of current varied from 1 to 68 μs, and the geometric mean values of 10%-90% risetime, charge transferred and action integral were about 1.9 μm, 0.86 C and 2.6 ×103 A2 s, respectively. The electric field at 30 m caused by a return stroke with peak current of 16.5 kA reached 56.0 kV/m. The geometric mean of magnetic field at 60 m was about 52 μT. View full abstract»

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  • AC power quality and surge protectors

    Publication Year: 2011 , Page(s): 1 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (489 KB) |  | HTML iconHTML  

    Since years the Surge Protective Devices (SPD) are widely used to protect the sensitive equipment connected to the AC distribution network against lightning or switching surge voltages. The international standards for SPDs are now widely spread and make the new generation of AC surge protectors more efficient and more secure. But an important issue is not really described on the standards and even on the related guides for surge protection application: what is the real influence of the AC surge protector on the AC network, especially during their operation? As we know, the Power Quality (PQ) is a key point for the process continuity, the safety and even for the life expectancy of the sensitive devices connected to the AC distribution network: during their operation on surges, the surge protectors could generate some phenomena which could create disturbances or troubles on the AC network. Because the AC surge protectors are from different technologies and because the AC networks could have several configurations, many cases are possible, even the worse... Market analysis shows sometimes a low confidence of the end user in the surge protection, not because he thinks it is not efficient, but because he supposes the use of SPD could bring extra disturbances on his installation. For this reason, an in depth information about the real interaction would be useful. View full abstract»

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  • Application investigation on parallel gap of composite insulators for 110 kV transmission line in high intensity lightning area

    Publication Year: 2011 , Page(s): 288 - 291
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (290 KB) |  | HTML iconHTML  

    The parallel gap lightning protection device is beneficial to the existing lightning protection measures for overhead transmission line and has broad application prospects. The application investigation on parallel gap lightning protection device of composite insulators for the 110 kV overhead transmission line used in high intensity lightning area is present in this article. A variety of parallel gap lightning protection device are designed. The functions of its guiding lightning discharge, transferring power-frequency arc, uniforming power-frequency electric field and protection of insulators and fittings are verified by tests. The lightning performance calculation after the installation of parallel gap device is carried out. Through optimization of the electrical parameters and dimensions of the gap, the samples are developed and used in five 110 kV transmission lines. The operation situation of the 110 kV line parallel gap lightning protection of composite insulator is introduced. The results show that the designs of the parallel gap for 110 kV transmission line composite insulators meet the requirements. The parallel gap is in good on-site operation condition. View full abstract»

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  • The electromagnetic leakage of the bounded-wave EMP simulator during the simulation of LEMP

    Publication Year: 2011 , Page(s): 292 - 295
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (164 KB) |  | HTML iconHTML  

    Bounded-wave EMP Simulator is often used in the simulation of the lightning electromagnetic environment. When simulate the lightning electromagnetic environment EMP simulator is working in the environment of high voltage and high field intensity. The simulator has an opening structure, and it will inevitably bring a certain radiation to its surroundings. The effect imposed onto the electronic equipment by the leak of the simulator should be considered. In this paper, the leakage of the EMP simulator is analyzed. Two states were taken into consideration: when the simulator is unloaded and when the equipment under-test (EUT) is placed in the simulator. The numerical result shows that the field intensity of the leakage falls rapidly as the distance from the simulator edge increase. When the distance from the working region of the simulator is more than 3.5m, the radiation field is less than twenty percent of the edge. View full abstract»

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  • 3D Air-termination design-support system

    Publication Year: 2011 , Page(s): 296 - 299
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (165 KB) |  | HTML iconHTML  

    A 3D air-termination design-support system for automatically estimating collection areas and analyzing areas of buildings that are either protected or unprotected by an air-termination system in three dimensions was developed for designing external lightning-protection systems. Using this system makes it possible to analyze complex building forms and design air-termination systems with efficiency and accuracy. View full abstract»

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  • Reconfigurable dual-band narrow bandpass filter using parallel two-section open stubs and z-domain technique

    Publication Year: 2011 , Page(s): 300 - 303
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    This paper proposes a z-domain technique to design a reconfigurable dual-band bandpass filter. An arbitrarily pre-defined bandpass filter is implemented by using parallel stubs. Switch circuits shunted with two-section stubs are employed to induce the narrow passbands on arbitrarily bandpass filters. The simulated results show that 3-dB bandwidths are 130 MHz and 70 MHz at the center frequencies of 1.55 GHz and 2.12 GHz, respectively. View full abstract»

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  • Upward lightning discharges: An update

    Publication Year: 2011 , Page(s): 304 - 307
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    Lightning discharges initiated by leaders that originate from stationary grounded objects, usually towers, and propagate upward, toward overhead thunderclouds, are reviewed. Upward, or object-initiated, lightning discharges always involve an initial stage that may or may not be followed by downward-leader/upward-return-stroke sequences. The initial-stage current often exhibits superimposed pulses whose peaks range from tens of amperes to several kiloamperes (occasionally a few tens of kiloamperes). View full abstract»

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  • Use of the full-wave finite element method for the numerical electromagnetic analysis of LEMP and its coupling with overhead lines

    Publication Year: 2011 , Page(s): 308 - 313
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB) |  | HTML iconHTML  

    The computation of lightning-originated surges on overhead power lines due to nearby lightning return strokes requires accurate models for the calculation of both the incident lightning electromagnetic pulse (LEMP) and the coupling of this field with the line conductors. The availability of numerical algorithms for the resolution of full-wave Maxwell's equations (also called numerical electromagnetic analysis - NEA) could provide benchmark results useful to assess the uncertainties introduced by approximate models and solution methods. Within this context, the paper presents and discusses the results of LEMP and lightning-induced voltages calculations obtained using a time-domain full-wave Finite Element Method (FEM) model. The results obtained by the FEM model are then compared with those provided by traditional approaches based, for the LEMP calculation, on the combined use of the dipole technique and the Cooray-Rubinstein formula and, for the LEMP-to-line coupling, on the Agrawal et al. model. View full abstract»

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