Sistemas de sensoriamento ópticos distribuídos aplicados ao setor de energia

Abstract

This work presents the development of two distributed sensor systems based on optical fiber applied to the energy sector. The first one is a distributed acoustic sensor (DAS) based on Rayleigh backscatter, applied to the oil and gas extraction sector. The second one is a vibration sensor based on time domain optical reflectometry (OTDR) combined with the Sagnac interferometry technique, applied for the detection of partial discharges in machines and electrical cables. The topology chosen for the DAS system was the amplitude demodulation of the backscattered signal (COTDR), the choice was defined based on the study of topologies, system requirements and component studies. To validate the system, simple tests to determine the speed of sound in the air and to determine the speed of propagation of mechanical waves in steel pipes were defined, the system presented good performance. The main features of the developed DAS system are spatial resolution of 1 m and sensor fiber with 2 km of length. The DAS system developed in this work was of fundamental importance for the continuity of the development of the system. The second sensor system has the main feature in the use of a low coherence light source. This characteristic makes the system more economical, allowing its use in less noble applications, but as important as the oil and gas extraction sector. The proposed system has a spatial resolution of 50 m. To validate the system and evaluate its ability to identify and locate electrical discharges, two tests were defined. In the first electrical discharges were applied to a conductive plate instrumented with optical fiber and in the second electrical discharges were applied to a section of insulated electrical cable instrumented with optical fiber. In both tests, the sensor system based on Sagnac interferometry was able to locate and identify the applied electrical discharges. The initial study of the system showed promising results, creating numerous possibilities for improvement.