Impulse Impedance of Grounding Grids

Gupta, Bhasker; Thapar, B.

doi:10.1109/tpas.1980.319800

Cited by 123 publications

(85 citation statements)

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“…In these and all other examples in this paper a median value of the soil's relative permittivity is adopted. The analysis in the paper is focused on the dominant influence of the soil resistivity, which is also an approach adopted in other simple formulas for the dynamic grounding characteristics [1], [22], [41]- [43]. In all cases, the injected current pulse is with peak value -, zero-to peak time -, and half-width -.…”

Section: Dynamic Behavior Of Ground Electrodesmentioning

confidence: 99%

“…Different approaches have been used in the literature to derive simple formulas for the grounding impulse parameters, for example, based on experimental methods [42], [43], and simplified circuit analysis [1], [22], [41]. However, the latter are based on the quasi-static approximation, which constrains the applicability to slow fronted pulses.…”

mentioning

confidence: 99%

“…However, the latter are based on the quasi-static approximation, which constrains the applicability to slow fronted pulses. As a consequence, it has been shown in [52] that commonly used formulas in [1], [41], are not applicable for front times less that 1-. In addition, previous approaches use unrealistic lightning current waveforms approximated by cosine [41] or exponential functions [43] that are characterized by a convex wave front with a maximum current derivative at .…”

mentioning

confidence: 99%

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Impulse Efficiency of Ground Electrodes

Grcev

2009

IEEE Trans. Power Delivery

156

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Abstract-The lightning current waveform has a major influence on the dynamic performance of ground electrodes. While high lightning current intensity improves the dynamic grounding performance due to ionization of the soil, very fast fronted pulses might worsen the performance in case of inductive behavior. The previous analysis has often been based on quasistatic approximation that is not applicable to very fast fronted pulses. To extend the analysis to fast fronted pulses in this paper, the full-wave analysis method based on the rigorous electromagnetic-field theory approach is used. In addition, realistic lightning current waveforms are applied, which reproduce the observed concave rising portion of typical recorded lightning current pulses. Based on the simulation results, new empirical formulas applicable for slow and very fast fronted lightning current pulses are proposed. The effects of the ionization of the soil are disregarded; therefore, the new formulas are applicable for a conservative estimate of the upper bound of the impulse impedance of ground electrodes.

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Section: Dynamic Behavior Of Ground Electrodesmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Impulse Efficiency of Ground Electrodes

Grcev

2009

IEEE Trans. Power Delivery

156

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“…This is called 'effective length' . So far, although the effective length of a grounding wire or an electrode has been studied and discussed on the basis of experiments or simulations in [2][3][4][5][6][7][8], they deal with an independent grounding conductor or electrode. The effective length of a grounding conductor, which is connected to the foundation of a large structure such as a wind turbine has not yet fully been studied.…”

Section: Introductionmentioning

confidence: 99%

Effective length of vertical grounding wires connected to wind turbine foundation

Miyamoto

Baba

Nagaoka

et al. 2017

Journal of International Council on Electrical Engineering

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Wind turbines are frequently struck by lightning. One of the important and effective measures is to reduce the grounding impedance of wind turbine. For the reduction of grounding impedance, vertical and/or horizontal conductors are additionally buried and connected to the foundation. It has been reported that there is a certain length of grounding conductor, beyond which the part of the grounding conductor is ineffective. This is called 'effective length' . In this paper, the effective length of a vertical grounding conductor is investigated through simulations using the FiniteDifference Time-Domain method.

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“…Because the impedance of grounding systems includes resistive, inductive and capacitive components at a high frequency, the grounding impedance rather than the ground resistance should be defined and evaluated. A lot of literature present the effective length of grounding electrodes and it means the expanded length and area of grounding electrode systems have a little effect to reduce the grounding impedance at a high frequency [2], [8,9]. Grounding impedance consists of resistive, capacitive and inductive components and the ground resistance is the real part of the grounding impedance measured at a low frequency [9].…”

Section: Introductionmentioning

confidence: 99%

Frequency-dependent grounding impedance of the counterpoise based on the dispersed currents

Choi¹,

Lee²,

Paek³

2012

Journal of Electrical Engineering and Technology

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-When surges and electromagnetic pulses from lightning or power conversion devices are considered, it is desirable to evaluate grounding system performance as grounding impedance. In the case of large-sized grounding electrodes or long counterpoises, the grounding impedance is increased with increasing the frequency of injected current. The grounding impedance is increased by the inductance of grounding electrodes. This paper presents the measured results of frequency-dependent grounding impedance and impedance phase as a function of the length of counterpoises. In order to analyze the frequency-dependent grounding impedance of the counterpoises, the frequency-dependent current dissipation rates were measured and simulated by the distributed parameter circuit model reflecting the frequency-dependent relative resistivity and permittivity of soil. As a result, the ground current dissipation rate is proportional to the soil resistivity near the counterpoises in a low frequency. On the other hand, the ground current dissipation near the injection point is increased as the frequency of injected current increases. Since the high frequency ground current cannot reach the far end of long counterpoise, the grounding impedance of long counterpoise approaches that of the short one in the high frequency. The results obtained from this work could be applied in design of grounding systems.

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Impulse Impedance of Grounding Grids

Cited by 123 publications

References 1 publication

Impulse Efficiency of Ground Electrodes

Impulse Efficiency of Ground Electrodes

Effective length of vertical grounding wires connected to wind turbine foundation

Frequency-dependent grounding impedance of the counterpoise based on the dispersed currents

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