Fiber-Optic Acoustic Sensors for Partial Discharge Detection in Power Cables

Partial discharge acoustic detection is a powerful technique for assessment of the insulation integrity of power cables. In contrast to conventional method in which piezoelectric transducers are commonly used to detect the partial discharge acoustic emission, fiber-optic sensors recently become excellent candidates for partial discharge acoustic detection because of their several benefits, such as immunity to electromagnetic interference and long range remote sensing capabilities. In this paper, we demonstrate a fiber-optic sensor system that can successfully detect the partial discharge acoustic emission from power cable joint defect. We first designed a fiber sensor coil that worked as the acoustic sensing element, and built an interrogation unit based on Sagnac interferometry to extract the detected acoustic signal from the fiber sensor coil. Then, a power cable joint defected by stress cone dislocation was used as the model to test the efficiency of our designed fiber-optic sensor system. An electric detection unit that conformed to the IEC 60270 was also used as a reference to monitor the partial discharge electric signals. The statistical analysis on the phase resolved pulses detected by the fiber-optic sensors and the ones detected by the electric sensors verify that the fiber-optic sensors can successfully detect the partial discharges induced within the stress cone dislocation of the power cable joint. We expect that fiber-optic sensors to become an excellent candidate for on-site partial discharge acoustic detection in the future.