Sobretensões em redes de distribuição decorrentes da incidência de descargas atmosféricas em torres de telecomunicações

Abstract

The number of radio-base telecommunication stations has been increasing significantly in urban areas. These stations are installed next to electric supplying distribution systems and always include elevated structures such as their towers or poles. These structures are frequently stricken by lightning, which is a major cause of damage to electric systems. This picture described above motivated this research entitled lightning overvoltage in distribution line next to telecommunication towers. In this context, this thesis was developed with the following objectives: (1) to investigate the overvoltage resulting from lightning strikes to the tower in the distribution systems next to telecommunication station and in the loads of nearby consumers and (2) to evaluate the role played by the many factors that affect the amplitude and shape of such overvoltage. Strikes to the tower with representative lightning current waves were simulated systematically in order to evaluate the corresponding overvoltage developed at the distribution line close to the communication tower. An elaborate computational model HEM (Hybrid Electromagnetic Model) was used to perform the simulations. The results revealed the influence of the most relevant parameters on the overvoltage developed at distribution lines, allowing separating the parcels associated to the induced voltage and to the grounding potential rise due to the current flow to the soil. The developments led to some relevant conclusions about the severity of such overvoltage that confirmed it as a potential source of distribution-system outages and of damages to the consumers' loads.