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48 results on '"Ishimoto, Kazuyuki"'

6. Direct Lightning Surge Analysis of Distribution Lines Considering LEMPs From Lightning Channel and Struck Pole in EMT Simulation

Author

Yamanaka, Akifumi, Ishimoto, Kazuyuki, and Tatematsu, Akiyoshi

Abstract

Direct lightning strikes mainly determine the lightning performance of medium-voltage distribution lines with surge arresters installed at close intervals. Recent studies have shown that in such lines, the effect of a lightning electromagnetic pulse (LEMP) on insulator voltages has a large impact on lightning performance assessment. In this article, we propose an analysis method that can consider the effect of LEMPs radiated from the lightning channel and the struck pole in electromagnetic transient (EMT) analysis. In the proposed method, first, the LEMPs are calculated using potential formulae that are extended to include the presence of the struck pole. Second, the insulator voltages induced by the LEMPs and generated by currents flowing into the struck pole, earth electrode, and shield wire are calculated using a field-to-line coupling formula interfaced with the EMT analysis. The proposed method is validated by comparison with three-dimensional finite-difference time-domain analysis. The proposed method is potentially a powerful tool for statistically assessing the lightning performance of distribution lines while considering LEMP effects.

Published
2023
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29. Study of Lightning Risk Evaluation of Distribution Systems.

Author

ISHIMOTO, KAZUYUKI, ASAKAWA, AKIRA, and SHINDO, TAKATOSHI

Subjects
*LIGHTNING, *RISK assessment, *ELECTRIC power distribution grids, *LIGHTNING protection, *POWER distribution networks
Abstract

SUMMARY Recently, concept of the lightning risk management has been proposed for the minimization of damages caused by lightning. In distribution systems (power distribution lines, low-voltage distribution lines, telecommunication lines, and customer appliances), lightning protection measures based on the lightning risk management are effective since the number of facilities is enormous. In this paper, for the establishment of lightning risk management method of distribution systems, we expressed the lightning risk assessment method of distribution systems and examined the influence of arrangement of customer house on the lightning risk values of power distribution lines and customer appliances. [ABSTRACT FROM AUTHOR]

Published
2017
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48. A New Calculation Method of the Lightning Electromagnetic Field Considering Variable Return Stroke Velocity

Author

Alberto Borghetti, Fabio Napolitano, Fabio Tossani, Carlo Alberto Nucci, Kazuyuki Ishimoto, Tossani, Fabio, Napolitano, Fabio, Ishimoto, Kazuyuki, Borghetti, Alberto, and Nucci, Carlo Alberto

Subjects
Electromagnetic field, Field (physics), Computer science, Acoustics, 020206 networking & telecommunications, 02 engineering and technology, Condensed Matter Physics, Lightning, Atomic and Molecular Physics, and Optics, Finite element method, 0202 electrical engineering, electronic engineering, information engineering, Waveform, Time domain, Electrical and Electronic Engineering, Induced overvoltages, lightning electromagnetic pulse (LEMP), overhead lines, return stroke velocity, Communication channel, Voltage
Abstract

The article proposes an improved method for the calculation of the electromagnetic field radiated by a lightning return stroke over a perfectly conducting ground. Specifically, the proposed time domain expressions allow a closed-form solution for the field produced by an impulse-current propagating upward along a vertical path with a given velocity. The expressions are valid for a wide class of engineering return stroke models and can be adopted also in case the return stroke velocity varies along the channel. The solution for an arbitrary current waveform can be obtained by the convolution of the current at the channel base with the electromagnetic field due to the impulse-current along the channel. The accuracy and advantages of the method are assessed by the comparison with those obtained by a finite-element method computer model. The expressions are implemented in the LIOV-EMTP-RV code for the calculation of the induced voltages in an overhead distribution line.

Published
2021

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