Desempenho de linhas de transmissão frente a descargas atmosféricas: influência do efeito corona na ruptura a meio de vão

• Ano de defesa: 2010
• Autor(a) principal: Leandro Veloso Cunha
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: engenharia elétrica; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/BUOS-8MCHLM

In the present scenario of the Brazilian Electric Sector, the unavailability of transmission lines due to transient faults is highly undesirable because it may lead to the incidence of fines and charges for power transmission utilities and damage to customers. In this context it is important to have appropriate tools and methodologies to estimate the performance of equipment and transmission lines. This work focuses on lightning performance studies of transmission lines that, in general, is influenced by several environmental aspects (lightning density along the line route, topography, soil characteristics), parameters of the line design tower height and type, cable distances, ground characteristics, etc..), and specific features of the lightning event responsible for the occurrence. In addition to the consideration of the traditional influent parameters indicated in the technical literature, this work takes into account some specific phenomena that influence the performance of extra-high voltage transmission lines and that are usually ignored in conventional software and methodologies, notably the midsapn flashover in the presence of Corona Effect and of Pre-breakdown currents. A case of performance of a real 500kV line is presented, including the study of the characteristics of the line and evolution of performance history. The performance of this line is simulated by a conventional commercial software to determine its applicability for studies on extra-high voltage lines, its advantages and complementary needs in relation to Corona phenomena, Pre-breakdown Currents and their influence on probability of midspan-flashover occurrences. Finally the Corona phenomena and pre-breakdown currents are considered as influent parameter in midspan flashovers. Regarding the corona effect, the work considers its relevance, development of techniques for modeling and testing of models for simulation. The probability of midspan flashovers considering the corona effect is evaluated by means of simulation for the real 550-kV trasnsmssion line. The effect of the pre-breakdown currents is considered by means of a qualitative approach