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Author: n.sene
Type: Publication
Date: 2015-04-02

Selection of MV/LV Transformers to be Protected by Surge Arresters against Indirect Lightning Overvoltages

Description:
The papers addresses the problem of locating surge protective devices in a medium voltage distribution network by means of an accurate computer model for the calculation of lightning induced overvolta... see moreges and a Monte Carlo statistical procedure. The indirect lightning performance of small network cells of different configuration are evaluated and used as a benchmark for the validation of the surge arrester locations provided by a genetic algorithm procedure. The obtained results appear useful for the lightning protection design of networks
with complex topology.

Authors: Alberto Borghetti, Fabio Napolitano, Carlo Alberto Nucci, Fabio Tossani, Gilnei J. G. Dos Santos, Donorvan R. Fagundes, Gustavo P. Lopes, Manuel L. B. Martinez

2014 International Conference on Lightning Protection (ICLP), Shanghai, China

Tag(s): distribution network; surge arresters; lightning protection.

Author: n.sene
Type: Publication
Date: 2015-04-01

Correlation of lightning events and faults in distribution power networks

Description:
The paper deals with the analysis of the possible correlation between cloud-to-ground lightning discharges and relay operations inferred by using the experimental data obtained means of a measurement ... see moreset-up, installed on an Italian MV distribution network, and a statistical procedure based on the coordinated use of the Italian Lightning Location System (LLS) CESI-SIRF, the monitoring systems of protection manoeuvres and an advanced simulation tool for the calculation of lightning induced overvoltages. The procedure takes into account the uncertainties related to the estimation of lightning stroke location and current amplitude provided by the LLS. The experimental set-up, composed by a distributed monitoring system, is able to measure a-periodic voltage transients characterized by a frequency content up to 4 MHz. Three of these units have been installed in the feeder of a three-phase overhead distribution network with a total length of 21 km. The same feeder is protected with overcurrent and zero-sequence relays whose operations are recorded by a monitoring system with a 10-ms sampling time. The data collected during one year of operation of the experimental set-up have been analyzed together with the data collected by the LLS for a 144 km2 area covering the equipped feeder and its surrounding area, in order to account for all direct and indirect lightning events that may have caused a relay intervention. The data have been also used to test the calculation model. The paper eventually reports the results of the correlation analysis carried out using the mentioned procedure, which is used to evaluate the probability that a specific event, detected by the LLS and time-correlated to relay operation, may have been the cause of a flashover in the network.

Authors: A. Borghetti, F. Napolitano, C.A. Nucci, M. Paolone, M. Bernardi, F. Rachidi, K. Yamabuki

CIGRE 2008 - a joint research project

Tag(s): Lightning protection, lightning-to-fault correlation, lightning location systems, lightning performance of distribution lines, induced overvoltages, a-periodic voltage transient measurement, EMTP.

Author: n.sene
Type: Publication
Date: 2015-04-01

Lightning-Induced Overvoltages Transferred Through Distribution Power Transformers

Description:
This paper deals with the calculation of lightning induced overvoltages on medium-voltage (MV) and low-voltage (LV) distribution networks taking into account the presence of MV–LV distribution trans... see moreformers and, in particular, the surge transfer through them. The influence of the high-frequency model adopted for the representation of the power transformer on the calculation results is analyzed, with regards to two different models, both identified and validated by means of laboratory measurements: namely, a simple π of capacitances, and the more complex one introduced by Morched, Marti, and Ottevangers in 1993. Accurate simulation results provide information on the adequacy of both models for the calculations of interest. Additional results, useful to evaluate the expected level of power quality and the benefits achievable by a proper installation of protection devices, are presented making reference to a realistic and complex configuration of an overhead distribution system

Authors: Alberto Borghetti, Atef Morched, Fabio Napolitano, Carlo Alberto Nucci, Mario Paolone,

IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 24, NO. 1, JANUARY 2009

Tag(s): Lightning, distribution transformers, overvolatges

Author: n.sene
Type: Publication
Date: 2015-04-01

Interaction Between Grounding Systems and Nearby Lightning for the Calculation of Overvoltages in Overhead Distribution Lines

Description:
The aim of the paper is to analyze overvoltages in overhead distribution lines induced by nearby lightning return stroke currents taking into account also the conductive coupling between the lightning... see more current injected into the soil and the line’s grounding system. Experimental results obtained in 2003 at the International Center for Lightning Research and Testing (ICLRT) in Florida have shown that significant currents were coupled with an overhead experimental line through its grounding system by nearby rocket-triggered lightning.
The paper first proposes a conductive coupling model between the lightning current injected into the soil and the nearby line grounding system, then presents the incorporation of such a model into the LIOV-EMTP computer code. The paper finally presents an experimental validation of the proposed models by making reference to results obtained during the above-mentioned triggered-lightning campaign.

Authors: F. Napolitano, M. Paolone, A. Borghetti, C.A. Nucci, F. Rachidi, V.A. Rakov, J. Schoene and M. A. Uman

Tag(s): lightning induced overvoltages, grounding systems, overhead distribution lines, lightning protection.

Author: AdminEMTP-RV
Type: Document
Downloaded: 478 times
Date: 2012-06-18

Presentation of an approach based on EMTP for the calculation of lightning induced overvoltages

Description:
Authors:
A. Xémard, P. Baraton, B. Bressac, N. Qako, J. Mahseredjian, G. Simard, J. Ribeiro, R. Tarafi, A. Zeddam.

Abstract:
LIPS (Lightning Impact on Power Systems) is a toolbo... see morex based on EMTP (DCG version) and devoted to the calculation of the failure rate of apparatus due to lightning. This software covers direct and induced lightning. It has been developed in a partnership project between France Telecom, Hydro-Québec and électricité de France. The induced lightning nearby the electrical system. It is based on the following computational steps:
1) For each overhead line and underground cable of the electrical system, two equivalent current sources are calculated in the frequency domain, representing the illumination of the conductors by external electrical field due to lightning. These sources are evaluated in the frequency domain, taking into account the variation of the parameters of lines and cables with frequency. The conductivity of the ground is taken as finite. The modal theory is applied in the case of multi-conductor cable or line.
2) The equivalent sources are converted into time-domain and then included in an EMTP representation of the system allowing a time-domain transient computation. this approach and follow by comparisons between induced overvoltages calculated by LIPS and results from the literature.

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