RACHIDI , Farhad

This paper is aimed at analyzing the influence of the frequency-dependent behavior of the ground electrical parameters (conductivity and ground permittivity) on the electromagnetic field radiated by a cloud-to-ground lightning return stroke. Both radiation in air (over the conducting ground plane) and underground are considered in the analysis....

The paper aims at defining a methodology to evaluate the lightning performance of a system of overhead distribution lines. As is well known, the evaluation of the lightning performance relies generally on a Monte Carlo approach that generates many different lightning events and calculates the corresponding overvoltages. To perform such...

One of the main issues that has to be faced when evaluating lightning-induced overvoltages on a realistic network configuration is to implement the algorithm that solves the field-to-line coupling problem into an electromagnetic simulator that is able to represent with a high level of detail all the power system components. On one hand,...

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The estimation of the lightning performance of a power distribution network is of great importance to design its protection system against lightning. An accurate evaluation of the number of lightning events that can create dangerous overvoltages requires a huge computational effort, as it implies the adoption of a Monte Carlo procedure. Such a...

Lightning overvoltages are one of the most dangerous factors affecting the power quality of a distribution grid. In medium voltage (MV) overhead distribution systems, lightning transients can be caused by either direct or indirect strikes. Indirect strikes are much more frequent than direct strikes and can cause flashovers, especially when the...

The paper addresses the important issue of evaluating the overvoltages produced on a power system by a lightning event. First, the theoretical formulation of the problem in the time domain is presented. Then its numerical solution together with its implementation is described. Finally, a PSCAD-EMTDC interface and platform is developed, which...

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The number of power installations lying underground has been increasing in the last few years, and such devices are very sensitive to the effect of the lightning electromagnetic fields, due to the massive presence of power electronics. As a consequence, the scientific community has devoted much effort in the direction of a more accurate...

In this paper, the developed formulation, which we shall call the "reference" one, is used to assess the validity of the most popular simplified approach for the calculation of the lightning electromagnetic field over a conducting earth, namely, the Cooray-Rubinstein (CR) approximation. This formula provides a simple method to evaluate the...

Severe weather events are responsible for hundreds of fatalities and millions of euros of damage every year in the Mediterranean basin. Lightning activity is a characteristic phenomenon of severe weather and often accompanies torrential rainfall, which under certain conditions like terrain type, slope, drainage and soil saturation can generate...

In a recent paper, a procedure to reconstruct the attenuation function of a return-stroke current from the simultaneous measurements of the channel-base current and the radiated electromagnetic fields was presented. One of the assumptions of the whole framework was that the sensors can record the overall time-evolution of the lightning...

In the present paper, we show, by means of numerical simulations, that electromagnetic field data obtained from the radiation of a return-stroke lightning discharge and measured over a short-duration time-window can be exploited to reconstruct the attenuation function of the lightning channel. To this end, we discretize the current-field...

The present paper presents the results of the comparison between a recently developed code for the evaluation of lightning-induced overvoltages in the PSCAD-EMTDC environment and the measurements on an experimental facility developed at the University of São Paulo, São Paulo, Brazil. The extensive validation campaign is performed considering...