Desenvolvimento e validação de metodologia para cálculo da posição de falhas em cabos isolados por meio da análise de sinais na blindagem metálica

Abstract

The detection of faults in insulated cables can be carried out through partial discharge measurements, using either offline or online operation modes. In contrast to the offline method, which requires system shutdown, the online mode enables cable diagnostics while the system remains energized. However, despite technological advancements, this approach presents limitations due to the sensitivity of the results to noise influence. Moreover, it does not allow for the precise localization of the fault point. The impedance-based method, applied in online mode for fault location, emerges as an alternative to overcome some of these challenges. Nevertheless, its application requires voltage and current measurements at both ends of the main conductor, and load variations increase the error in the location algorithm results. This work investigates the use of parameters and signals from the metallic sheath of insulated cables to calculate the position of incipient faults, based on the two-terminal impedance fault location method. The analysis shows that applying the method to the metallic sheath eliminates the need for measuring phase currents and improves the results by 55.86% when compared to the application of the same method to the main conductor.The proposed approach offers advantages that enable the detection of incipient faults online and the calculation of their location before they evolve into permanent failures. Thus, this work contributes to the stability of insulated networks, reducing supply discontinuities and improving the quality of service delivered to users.