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Tehrān, Iran

Izadi M.,University Putra Malaysia | Ab Kadir M.Z.A.,Islamic Azad University at Firoozkooh | Hajikhani M.,Aryaphase Company
Journal of Electrical Engineering and Technology | Year: 2013

Lightning electromagnetic fields are important issues for the evaluation of lightning induced overvoltage on power lines and for setting the appropriate protection level for power networks. Such electromagnetic fields are strongly dependent on lightning return stroke currents at different heights along the lightning channel. On the other hand, the ground reflection factor due to the difference between the return stroke channel impedance and the equivalent ground impedance at channel base can have an effect on the shape of the return stroke currents by entering additional reflected currents into the channel. In this paper, the effect of the ground reflection factor on the return stroke currents at different heights along a channel and the electromagnetic fields associated with the lightning channel at close distances are considered. Moreover, the behavior of the electromagnetic fields versus the reflection factor changes and the radial distance changes are considered and the results are discussed accordingly. The results illustrate that the reflection factor has a direct relationship with the values of the electromagnetic fields while this is usually ignored in earlier studies.


Izadi M.,Islamic Azad University at Firoozkooh | Izadi M.,University Putra Malaysia | Ab Kadir M.Z.A.,Islamic Azad University at Firoozkooh | Hajikhani M.,Aryaphase Company
2014 International Conference on Lightning Protection, ICLP 2014 | Year: 2014

In this paper an inverse procedure algorithm in the time domain is proposed to evaluate the wave shape of the lightning return stroke current along a lightning channel using measured electromagnetic fields obtained at different distances with respect to the lightning channel. Moreover, the proposed method was applied on an actual sample of lightning current and the results discussed accordingly. The proposed method takes into consideration all the field components which cover the full shape of the current. Thus the method can be helpful for preparing a lightning current data bank and setting a proper protection level for a power system based on local information. © 2014 IEEE.


Izadi M.,University Putra Malaysia | Izadi M.,Islamic Azad University at Firoozkooh | Ab Kadir M.Z.A.,University Putra Malaysia | Hajikhani M.,Aryaphase Company
Journal of Electrical Engineering | Year: 2014

In this paper, general electric field expressions are proposed to consider the effect of channel base ground reflections and ground conductivity on the electric field components due to lightning. The proposed method can support different current models and functions directly in the time domain without the need to apply any extra conversions. The proposed method is applied on a sample of measured channel base current from triggered lightning experiment and the results are discussed accordingly. The results show that the ground reflection and ground conductivity can have an effect on the peak values of the electric fields whereby the electric field components have a great effect on the widely used coupling models. © 2014 FEI STU.


Izadi M.,University Putra Malaysia | Izadi M.,Islamic Azad University at Firoozkooh | Ab Kadir M.Z.A.,University Putra Malaysia | Hajikhani M.,Aryaphase Company
Journal of Electrical Engineering and Technology | Year: 2014

Lightning induced voltage is a major factor that causes interruptions on distribution lines. In this paper, analytical expressions are proposed to evaluate a lightning induced voltage on power lines directly in the time domain without the need to apply any extra conversions. The proposed expressions can consider the widely used current functions and models in contrast to the earlier analytical expressions which had a number of limitations related to the simplification of the channel base current and the current along the lightning channel. The results show that the simulated values based on the proposed method are in good agreement with the previous studies and the proposed expressions can be used for optimizing the insulation and protection level of existing and new lines being designed.


Izadi M.,University Putra Malaysia | Izadi M.,Islamic Azad University at Firoozkooh | Ab Kadir M.Z.A.,University Putra Malaysia | Hajikhani M.,Aryaphase Company
Mathematical Problems in Engineering | Year: 2014

The analytical field expressions are proposed to estimate the electromagnetic fields associated with vertical lightning channel at an observation point directly in the time domain using current and geometrical parameters. The proposed expressions embrace a large number of channel base current functions and widely used engineering current models. Moreover, they can be joined with different coupling models for evaluation of lightning induced voltage when they provide different required field components directly in the time domain. The data from measured fields and simulated fields from previous works were employed to validate the proposed field expressions. The simulated results were compatible with both computed field values from previous studies and the measured fields. © 2014 Mahdi Izadi et al.

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