Um estudo da influência da geometria das torres e da distribuição de corrente de descarga na estimativa do desempenho de linhas de transmissão frente a descargas atmosféricas

Abstract

The objective of the work is to evaluate the influence of considering different types of structures along the line, the variation in the height of different towers along the LT route and the cumulative distribution of discharge current peak values on the calculation lightning line performance. The main models of the components of a transmission line (TL) are presented, analyzed and implemented in order to evaluate the effect of these on the lightning performance of the TL. The proposed methodology is explained in standards and brochures for calculating line performance and methodologies and modeling are proposed in order to make the estimation of line outages more assertive and consistent with values and behaviors observed in the field. The main modeling of the components of a transmission line (LT) are presented, analyzed and implemented in order to evaluate their effect on the lightning performance of the LT. The work evaluates the impact of representing a detailed distribution of towers on the estimation of line shutdowns due to backflashover. A line composed of suspension, anchoring and guyed structures and current waves representative of Monte San Salvatore and Morro do Cachimbo is evaluated. The shutdown rates associated with the transmission line are presented, considering each of the three structures as being representative of the behavior of the line as a whole and the performance of the LT considering in the calculation not only a type of representative structure, but a distribution considering the effect of the geometry of each tower on the performance of the entire transmission line. The outage rate obtained using the distribution of structures is 11.3% and 10.8% lower than that estimated considering a dominant structure, considering the statistical distributions of the discharge currents of Monte San Salvatore and Morro of Cachimbo, respectively. The work also evaluates the effect of varying the height of the line's towers on its performance against discharges. Depending on the different relief conditions and route of the TL, the height of the structures that make it up varies. A line is considered with self supporting suspension and guyed structures and different height values for each type of geometry. Another important factor evaluated is the impact of the distribution of the peak value of lightning currents on the line backflashover rate. The performance of a line composed of self-supporting suspension structures is evaluated using the distributions related to measurements carried out at the stations of Monte San Salvatore, Morro do Cachimbo, on transmission lines in Japan obtained by Takami and Okabe and the distributions recommended by the IEEE and by CIGRÉ. The impact of considering or not considering these distributions on the calculation of the attraction area of a transmission line and consequently on the number of discharges that affect the line is also evaluated. The simulations are carried out in ATP and the critical currents are obtained using the Disruptive Effect Method. Based on the results obtained, the aim is to propose methodologies for modeling and calculating the performance of transmission lines in order to obtain results that are more in line with reality and facilitate the identification of critical sections of the line for more assertive action in protecting the line. transmission in the face of lightning.