Detecção e localização de descargas parciais a partir de envelopes de sinais radiométricos.

Abstract

Partial Discharges (PD) are low-intensity electrical discharges that can gradually degrade the insulation systems of high-voltage equipment. Over time, this can damage the equipment, resulting in the unavailability of the electrical system. Therefore, monitoring these discharges can become a useful tool for predictive maintenance. During the occurrence of this phenomenon, electromagnetic waves are emitted in the ultra high frequency range, enabling the use of non-invasive sensors such as antennas to monitor the equipment, even during operation. The localization step is particularly crucial in this process, as determining the position of the equipment with dielectric faults, or even the internal position of these faults, can reduce maintenance time. In the radiometric method, traditionally, the coordinates of faulty equipment are estimated using the time difference of arrival method. However, the effectiveness of this method requires a high sampling rate instrumentation system, making the acquisition system complex. One way to simplify it is to perform envelope detection of these signals. In this work, experimental setups were developed to evaluate this approach, both from the detection and localization perspectives of partial discharge sources, using commercial envelope detectors. Regarding detection, measurements were taken on different equipment to evaluate the effectiveness of the envelope detection circuit for radiometric signals with different voltage values, using the PD signal captured by the antenna as a reference. Concerning localization, radiometric measurements were performed on different experimental setups. From there, two approaches were investigated to determine the location of the PD source: the first one based on the time difference of arrival method, and the second based solely on the signal amplitude. It was concluded from the signal analysis that envelope detection is sufficient to assess the evolution of PD activity in a measurement cycle. Regarding localization, it was observed that envelopes are sufficient to determine the region where the equipment is located.