Fiber Bragg grating-based sensing system for real-time monitoring of galloping and torsional behavior in overhead transmission lines

This paper presents a fiber Bragg grating (FBG)-based sensing system for real-time simultaneous monitoring of galloping and torsional deformations in overhead transmission lines. The system utilizes a tri-cantilever structure with four surface-mounted FBGs to separately detect vertical displacement and torsional angle. A dual-FBG differential configuration is adopted to compensate for temperature drift, enabling robust strain measurement. Experimental validation on a 70-meter scaled conductor demonstrated high accuracy, achieving a galloping sensitivity of 9.55 × 10^-3nm/cm (R² = 0.9896) and a torsional sensitivity of 7.21 × 10^-3nm/rad(R² = 0.9758). Under coupled excitation, the system successfully resolved coexisting vibration modes and exhibited clear spectral transitions across different dynamic regimes. The proposed sensor enables effective and simultaneous monitoring of galloping and torsional deformation in overhead transmission lines, providing a practical tool for dynamic behavior analysis and structural risk assessment.