Passive wireless measurement of tension for overhead transmission line based on surface transverse wave

This study presents a passive wireless surface transverse wave (STW) torsion sensor for an overhead transmission line (OHTL). Two key techniques, namely the design of STW sensing element and clamping structure, were investigated. The relationship between the tension and the frequency shift of the STW resonator was analysed. A numerical analysis on the tension sensitivity and temperature coefficient using different cut types was performed. Results showed that Y − 51° cut quartz, which has a close to zero temperature coefficient of frequency, is a suitable substrate of the STW tension sensors. Other parameters were optimised to obtain a resonator with a Q value of >11,000. Two STW resonators were adopted as sensing element to form a differential structure to reduce the temperature interference. An OHTL clamping and tension transfer mechanical structure was designed, which has an ability of adjusting the tension sensitivity and can be easily installed at any point of OHTL. Moreover, the OHTL tension measurement system was set up and evaluated. Experimental results indicated that the STW tension sensitivity was 24.31 kHz/kN, the non-linearity was 0.26%, and the repeatability error was 0.32%. The OHTL tension measurement method is feasible for practical application.