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Nowadays, electricity consumption is closely linked to the economic growth of cities, states, and countries, providing a better quality of life and security. Overhead power distribution networks at medium- and low-voltage levels are responsible for serving and supplying electricity to the largest consumer class, as they represent most consumer installations. Due to this reason, there is a vast expanse of exposed networks vulnerable to the effects of atmospheric discharges. Therefore, the objective of this article is to implement and evaluate the models available in the literature to represent distribution networks during transient events caused by lightning, using simulation in ATPDraw. These structures pose a significant complexity in their representation, and there are studies that assess more accurate methods for simulating transients in transmission lines, which have different structural and configuration characteristics. Ultimately, the results demonstrate that the choice of which model to implement in a simulation heavily depends on the analysis to be conducted by the researcher, and it can be observed that more accurate methods do not always yield substantial differences in the obtained outcomes. [ABSTRACT FROM AUTHOR]

• Cable coupling interferes with measurements of grounding resistance. • Low resistivity concrete enhances grounding performance. • Lightning wavefront times are important for grounding analysis. • Transmission line grounding shows inductive behavior. • Concrete electrode shows capacitive behavior. One of the main causes of outages in transmission lines is lightning. To mitigate this occurrence, grounding electrodes are used at the base of the towers that make up the transmission lines. Since lightning is a phenomenon with components of low and relatively high-frequency energy (approximately up to 2 MHz), there is a certain complexity in accurately characterizing grounding systems. The primary parameter used to model a grounding system is the grounding impedance, which can be obtained through measurement. This paper presents measurements conducted on a 138 kV transmission line's traditional and alternative grounding system. The measured traditional grounding system consists of two horizontally buried copper grounding conductors and the alternative system comprises an electrode with four conductors encapsulated in concrete and buried vertically. The measurements were carried out using a 25 kHz earth resistance meter and impulse generators with waveform shapes of 1.2/50 μs, 1/70 μs, and 8/70 μs. Different measurement configurations are employed. The obtained measurements are compared with similar systems found in the literature, and the contributions of the concrete electrode to the grounding system are discussed. [ABSTRACT FROM AUTHOR]

This paper promotes the use of prediction methods as an alternative tool for evaluating and managing electromagnetic compatibility (EMC) in hospital environments. Radiated emissions originated from medical equipment are modeled based on open area test site measurements, and they are applied to numerical simulation using transmission line matrix method (TLM). TLM simulation is performed to include not only the multipath effects provided by obstacles, but also the interaction and coupling of all different sources/models operating simultaneously on the environment under test (a typical operating room). This approach provides a useful tool in order to assess electromagnetic profiles established within the room area, and it allows implementing optimization processes such as genetic algorithms (GA). GA is employed to evaluate many different placements of medical equipment within the environment under test. A fitness function is defined to minimize the average electric field inside the room, providing a better equipment disposal to develop a preliminary EMC management program. [ABSTRACT FROM AUTHOR]

In this paper, a procedure for estimating the electromagnetic fields radiated far from their source based on near-field (NF) simulation is considered. The NFs radiated from the sources are modeled with the transmission-line matrix method. The so-called far fields are estimated with the help of different artificial neural networks. Comparison with results based on theoretical equations and software simulations substantiate the validity of the proposed method association. [ABSTRACT FROM AUTHOR]

Lightning is the major cause of disturbances on overhead distribution lines. Actions to reduce this problem depend on complex calculations and, in some cases, on significant investments. This paper presents software, which allows analyzing the lightning performance of overhead distribution lines as a function of the characteristics of these lines and respective regions. In addition to a summary of the procedures and calculation tools adopted, results are also presented here from the application of this program in general. Due to its friendly interface, experiences with the use of this software have shown good results, allowing integrated analysis of possible solutions. [ABSTRACT FROM AUTHOR]

This paper presents the combination of two different techniques [transmission line modeling (TLM) and Kriging methods] in the sense to optimize the effective signal cover inside buildings searching for the optimal transmitters locations in indoor wireless system. [ABSTRACT FROM AUTHOR]

This paper presents a new design for a three-dimensional cell for the TLM method, and its application in the resonator analysis. The new proposed cell is based on ‘π-type’ transmission line, and it uses incident and reflected currents. A condensed scattering matrix is developed. The computational results are compared with the analytical results and with TLM-SCN (symmetrical condensed node) computational results. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• Ignoring or neglecting the contribution of the characteristic impedance of transmission or distribution structures during overvoltage transient periods allows protection adjustments to be considered inappropriately. • This work presents in detail the process for determining the characteristic impedance of transmission and distribution structures by simulation using Q3D extractor software. • The use of computer programs presents greater reliability in the results and therefore, using numerical methods to determine the characteristic impedance of structures is a simple, fast and reliable method. • Determining the characteristic impedance of structures through a simulation program using numerical methods has great advantages over analytical methods, as it allows considering the electromagnetic properties of materials and a high level of geometric detailing of the structure. The characteristic impedance of structures is an important parameter used in the development of overvoltage protection studies and in the insulation coordination in electrical systems. The transmission line towers shapes and the poles shapes make it difficult to calculate the characteristic impedance analytically, or even measuring in laboratory. Thus, this paper presents a methodology to calculate the characteristic impedance of concrete poles in distribution networks and transmission line towers. A model was developed in Q3D Extractor software to run these simulations. A comparison between simulations and an analytical method is made, considering two types of structures, a distribution pole, and a transmission tower. The results show divergences between the calculated values by the various analytical methods and those obtained in this work. At the end, it is concluded that the determination of the characteristic impedance using the proposed methodology is more accurate due to the degree of structure details considered. [ABSTRACT FROM AUTHOR]