"Afundamentos de tensão no contexto da expansão dos sistemas elétricos: proposta de índices considerando dados do sistema de detecção de descargas atmosféricas"




The impact of voltage sags to power utilities and consumers has been remarking this event as a relevant phenomenon to address in power system studies. It is considered one of the most frequent sources of power-supply interruption and malfunction on several types of equipment, resulting in power-quality degradation. Nowadays, voltage sag has been basically addressed by means of corrective actions during system operation. This thesis proposes a preventive approach to address this event, including the corresponding analyses in the Expansion Planning activities. The proposed methodology is based on the conception of Voltage Sag Indices to be applied in the development of expansion plans to indicate the planner the most suitable expansion alternatives. These indices are designed to indicate the severity level of voltage sag occurrence as a function of three main parameters: magnitude, duration and frequency. The influence of each one of such parameters on the power system performance was investigated, taking into account the differences of topology and features of electrical power systems. Particularly, since lightning-related short-circuits are known as the main cause of voltage sags, the influence of the non-uniform geographic distribution of lightning incidence along the transmission system was explored. In this respect, an innovative aspect of this work consists in the use of data provided by Lightning Location System (LLS) to compose the mentioned indices. In this work, the application of the proposed indices in the expansion process is detailed by simulations applied to real power systems. It is shown how critical points along the transmission network can be identified in the early stages of system planning to prevent the occurrence of voltage sags. The results show that the application of the presented strategy leads to the improvement of power system performance.


engenharia elétrica teses.

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