Ferley Castro-Aranda

Lightning performance analysis of overhead transmission lines using the EMTP

This paper presents a procedure for the calculation of lightning flashover rates of transmission lines using a Monte Carlo method. The procedure has been implemented in the Alternative Transients Program version of the Electromagnetic Transients Program. Parametric studies using this procedure can also be performed to determine the sensitivity of the flashover rate with respect to some parameters of the transmission line and the return stroke. Some refinements are proposed to decrease the computer time while preserving the accuracy of calculations.

Tower modeling for lightning analysis of overhead transmission lines

A sensitivity study of the lightning flashover rate of transmission lines is presented in this paper. The study is aimed at analyzing the influence of the tower model on the flashover rate derived from the application of a time-domain Monte Carlo procedure. The main conclusion from the simulation results presented in this paper is that the selected tower model can significantly affect the flashover rate and its influence increases with the tower height.

Lightning Flashover Rate of an Overhead Transmission Line Protected by Surge Arresters

Surge arresters can improve the lightning performance of transmission lines. The flashover rate of a shielded transmission line protected by surge arresters can be negligible when arresters are installed at all phases and all towers. But even if arresters are not installed at all phases, some improvement can be achieved. However, arrester failure can be caused when the energy discharged exceeds the maximum absorption capacity. Therefore, arresters must be selected taking also into account energy discharge stresses. This paper is aimed at analyzing the lightning performance improvement of a shielded transmission line that can be achieved by installing surge arresters and the energy capability to be selected for arresters as a function of the number of phases at which they are installed.

Lightning performance analysis of transmission lines using the EMTP

This paper presents the analysis of the lightning performance of transmission lines using a statistical approach. The main goal is to determine the flashover rate of a line. The study is based on the application of the ATP version of the EMTP and the development of a Monte Carlo based procedure. Parametric studies have been performed to determine the sensitivity of the flashover rate with respect some parameters of the transmission line and the return stroke.

Influence of the stroke angle on the flashover rate of an overhead transmission line

Lightning discharges follow tortuous paths, so the usual assumption of a vertical leader channel is not realistic. This paper is aimed at exploring the influence that a non-vertical channel of the stroke leader can have on the lightning flashover rate of overhead transmission lines. The study is based on a Monte Carlo procedure implemented in an electromagnetic transients program, for which advanced models of the various transmission line parts involved in calculations have been developed

Modeling overhead transmission lines for line arrester studies

Surge arresters are installed in transmission lines to improve their lightning performance. To date simulation, usually based on EMTP-like tools, has been extensively used for evaluation of line arrester energy stresses. However, simulation results depend on the models chosen for representing the line. This aspect is particularly important for some parts of the line, e.g. tower footing impedances. The main goal of this paper is twofold: analyze the influence that some modeling approaches can have on arrester energy discharge and decide how the line has to be represented for an accurate calculation of energy stresses.

Lightning Performance Analysis of an Overhead Transmission Line Protected by Surge Arresters

In general, the main causes of unacceptable lightning flashover rates of overhead transmission lines are a bad shield design or too high footing impedances. The first reason will cause unacceptable shielding failure flashover rates (SFOR); the second one can cause high backflashover rates (BFOR). The lightning flashover rate of a shielded transmission line can be reduced by installing surge arresters. In fact, the rate can be reduced to zero by installing arresters at all phases and all towers of the line, but even if arresters are not installed at all phases, a significant improvement of the lightning performance can be achieved. However, arresters have to be selected to withstand the energy stresses caused by lightning strokes; otherwise, failures could be caused by an excess of energy absorption. This paper is aimed at analyzing the lightning performance improvement of a shielded transmission line that can be achieved after installing metal oxide surge arresters as a function of the number of phases at which they are installed and at estimating the energy absorption capability of the selected arresters.

MODELING OF OVERHEAD TRANSMISSION LINES FOR LIGHTNING OVERVOLTAGE CALCULATIONS

Resumen es: Un modelo de linea aerea de transmision adecuado para el calculo de sobretensiones originadas por el rayo debe incluir varias partes de la linea: conduct...

EMTP IMPLEMENTATION OF A MONTE CARLO METHOD FOR LIGHTNING PERFORMANCE ANALYSIS OF TRANSMISSION LINES

An accurate calculation of lightning overvoltages is an important issue for the analysis and design of overhead transmission lines. The different parts of a transmission line that are involved in lightning calculations must be represented taking into account the frequency ranges of transients associated to lightning. In addition, the procedures to be used in these calculations must be developed considering the random nature of lightning phenomena. Several simulation tools have been used to estimate the lightning performance of transmission lines. The most popular approaches are those based on a time-domain simulation technique for which adequate procedures and transmission line models have to be developed. This paper presents a summary of the computational efforts made by the authors for the development and implementation in an EMTP-like tool of a Monte Carlo procedure, as well as the models of some transmission line components, aimed at analyzing the lightning performance of transmission lines. An actual test line is used to illustrate the scope of this procedure and the type of studies that can be performed.

Lightning characterization for flashover rate calculation of overhead transmission lines

Lightning characterization for engineering applications is not easy: a flash can be either of negative or positive polarity; negative flashes can consist of several strokes; the waveform and the parameters of the first and the subsequent strokes are very different from each other. This paper is aimed at exploring the influence that a complete characterization of a lightning flash will have on the flashover rate of a transmission line using a Monte Carlo procedure that has been implemented in an electromagnetic transients program