Effect of vertically extended strike object on the distribution of current along the lightning channel

Rachidi, Farhad; Rakov, Vladimir A.; Nucci, C.A.; Bermúdez, José Luis

doi:10.1029/2002jd002119

Cited by 123 publications

(107 citation statements)

References 12 publications

(20 reference statements)

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“…We begin with the same assumptions made in recent studies [e.g., Guerrieri et al, 1998;Janischewskyj et al, 1996;Rachidi et al, 2001;Rakov, 2001;Rachidi et al, 2002]. A debate has recently arisen [e.g., Kordi et al, 2002;Thottappillil et al, 2001Thottappillil et al, , 2002 concerning the validity of a lossless transmission line assumption for the case of a vertical structure above a ground plane.…”

Section: Model Of a Vertically Extended Strike Objectmentioning

confidence: 99%

“…[11] Figure 1b presents a generalized equivalent circuit adapted from Rachidi et al [2002]. In Figure 1b, the current source represents the lightning channel with its associated equivalent impedance, Z ch .…”

Section: Model Of a Vertically Extended Strike Objectmentioning

confidence: 99%

“…In those studies, the authors inferred the value of the reflection coefficients from a reduced experimental set of current waveforms found in the literature [Beierl, 1992;Montandon and Beyeler, 1994b;Willett et al, 1988]. To decontaminate the current, Guerrieri et al [1998] proposed a formula, corrected by Rachidi et al [2002], as explained in section 2, that involves an infinite summation in the time domain, assuming that the reflection coefficients, r t and r g , are constant and known. Gavric [2002] proposed an iterative method based on the Electromagnetic Transient Program (EMTP) to remove superimposed reflections caused by a strike tower from digitally recorded lightning flash currents.…”

Section: Introductionmentioning

confidence: 99%

“…[8] In this paper, we obtain a closed form expression for the infinite summation formula of Rachidi et al [2002] both in the time domain and in the frequency domain considering the possible frequency dependence of the reflection coefficients. Further, we show how the reflection coefficient at the ground can be obtained from lightning current measurements at two different heights along the elevated strike object.…”

Section: Introductionmentioning

confidence: 99%

“…[7] Rachidi et al [2002], on the basis of a distributedsource representation of the lightning channel, generalized the mathematical formulations of the so-called engineering lightning return stroke models to take into account the presence of a vertically extended strike object. The distributed-source representation of the lightning channel adopted in their study allowed for more general and straightforward formulations of the generalized return-stroke models than the traditional representations implying a lumped current source at the bottom of the channel, including a selfconsistent treatment of the impedance discontinuity at the tower top.…”

Section: Introductionmentioning

confidence: 99%

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Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

et al. 2003

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[1] In this paper, we present an analysis of lightning return stroke currents along an elevated strike object. We derive closed form expressions, both in the frequency domain and in the time domain, to calculate the lightning current at any height along a strike object taking into account reflections at the top and at the bottom. The frequency dependence of reflection coefficients is taken into account. We also derive an expression to calculate the reflection coefficient as a function of frequency at the bottom of the lightning strike object from two currents measured at different heights along the strike object. We show that, if the current and its time derivative overlap with reflections at the top or bottom of the strike object, it is impossible to derive the reflection coefficient at the top of the strike object exactly from any number of simultaneous current measurements. We propose an extrapolation method to estimate this reflection coefficient. We propose a second method to calculate the top reflection coefficient from just one current derivative measurement if the current derivative and its reflections do not overlap significantly. We apply the proposed methodology to experimental data obtained on Peissenberg Tower (Germany) consisting of lightning currents measured at two heights. The results suggest that the reflection coefficient at ground level can be considered as practically constant in the frequency range 100 kHz to 800 kHz. Although the estimated ground and top reflection coefficients are in good overall agreement with values found in the literature, the estimated values for the top reflection coefficient from the extrapolation method are somewhat lower than those found employing the current derivative method; the differences are discussed.

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Section: Model Of a Vertically Extended Strike Objectmentioning

confidence: 99%

Section: Model Of a Vertically Extended Strike Objectmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

et al. 2003

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On the field-to-current conversion factors for lightning strike to tall objects considering the finitely conducting ground

Zhang

et al. 2014

J. Geophys. Res. Atmos.

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In this paper, we have studied the accuracy of field-to-current conversion factors (FCCFs) presented by Baba and Rakov (2007) for currents inferred from electromagnetic field produced by lightning strike to tall objects, considering the perfectly and finitely conducting ground, respectively. For the perfectly conducting ground, the different FCCFs for the initial peak current at the object top, the short-circuit current peak, the largest peak current at the object top, and the peak current at the object bottom have different accuracy ranging from underestimation of 18% to overestimation of 10% for the reflection coefficients at the two ends of object ρ t = À 0.5 and ρ b = 1.0, and from underestimation of 25% to overestimation of 10% for ρ t = À 0.5 and ρ b = 0.7; and their accuracy decreases with the increase of current risetime RT. For the finite conductivity with 0.01 S/m and 0.001 S/m, FCCFs will cause many errors if we do not take into account the propagation effect along the finitely conducting ground, and their errors obviously increase with the decrease of the conductivity. For example, for ρ t = À 0.5 and ρ b = 1.0, the errors are about 20% when the conductivity is 0.01 S/m while the errors are about 55% when the conductivity is 0.001 S/m for lightning strike to the 168 m high object. Therefore, we revised FCCFs by considering the propagation effect of finite conductivity on the electromagnetic field radiated by lightning strike to tall objects and found that our revised FCCFs have much better accuracy for the lossy ground than that presented by Baba and Rakov (2007).

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On the field‐to‐current conversion factors for large bipolar lightning discharge events in winter thunderstorms in Japan

et al. 2015

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In this paper we have simulated the far-field waveform characteristic of large bipolar events (LBEs) occurred in winter thunderstorms in Japan and compared the field-to-current conversion factors (FCCFs) of LBEs with that of the lightning cloud-to-ground (CG) return stroke (RS) in summer thunderstorm. As for the physical process of LBEs, Wu et al. (2014) considered that LBEs may be very similar to the typical lightning RS (RS-like process) or caused by an initial continuous current pulse (ICC-like process) in upward lightning flashes. We assume that the lightning channel length of LBEs ranges from 500 m to 1000 m, and the height of tall object struck by LBEs is from 100 m to 300 m. By using the bouncing wave model, we found that only when the injected current waveform of LBEs is characterized with a symmetric Gaussian pulse, the simulated far-field waveform of LBEs both for RS-like process and ICC-like process is similar to that observed by Wu et al. (2014). For striking tall objects with heights from 100 m and 300 m, the FCCFs of LBEs are positively correlated with its channel length and derivatives of injected current waveform, and the FCCF for RS-like process is about similar to that for ICC-like process. However, the FCCFs of LBEs are very different from lightning RS in summer thunderstorm; that is to say, the FCCFs developed for the well-known lightning RS in summer thunderstorm are not suitable for LBEs.

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Effect of vertically extended strike object on the distribution of current along the lightning channel

Cited by 123 publications

References 12 publications

Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

Determination of reflection coefficients at the top and bottom of elevated strike objects struck by lightning

On the field-to-current conversion factors for lightning strike to tall objects considering the finitely conducting ground

On the field‐to‐current conversion factors for large bipolar lightning discharge events in winter thunderstorms in Japan

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