Thermal monitoring of live-line power transmission lines with an infrared camera mounted on an unmanned aerial vehicle

This study proposes a thermal monitoring method in outdoor environments to inspect the health state of overhung transmission lines (TLs) with an infrared camera mounted on an unmanned aerial vehicle (UAV). The suggested method features three characteristics. First, the thermal energy of TLs measured by an infrared camera is converted into accurate temperature accounting for the conversion principle of the infrared camera. Characteristic parameters in the conversion principle, including emissivity, transmissibility, and reflectability, are systematically quantified through experiments. Second, a simple yet effective postprocessing method is proposed to eliminate thermal energy emitted from other heat sources in outdoor environments. Third, an automatic line-tracking method is proposed to focus on TLs for reliable thermal imaging during patrol inspection. The proposed method with an infrared camera deployed on a UAV is field-tested through an autonomous flight and gimbal control. A systemic analysis on field tests demonstrates that the proposed method overcomes several bottlenecks in current technologies and reveals several important considerations regarding thermally monitoring overhung TLs in outdoor environments. This insightful discovery supports developing a fully autonomous solution for accurate outdoor thermal imaging despite the many challenges that remain.