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In this paper, we propose and demonstrate a high precision three-dimensional (3D) ellipse fitting correction method for optical fiber composite overhead ground wire (OPGW) galloping monitoring, based on weak fiber Bragg grating array. 3D ellipse formed by three outputs of the system is fitted by the coordinate rotation and least square methods, and direct current (DC) components and alternate current (AC) component coefficients of the three outputs are obtained. By differentiating and cross-multiplying the three outputs, those DC components are zeroized, AC component coefficients are normalized, and finally, the interference phase signal is calculated. The experimental results show that the proposed method can demodulate the vibration signals better, and the fitted R2 is above 0.99. The system is implemented on a 220 kV transmission line in the plateau region of Western China, forecasting a galloping period with a wavelength of about 60 m within the span accurately. This method demonstrates suitability for monitoring OPGW transmission line galloping events. [ABSTRACT FROM AUTHOR]

To solve the problem of transmission line galloping monitoring for optical power grounded waveguides (OPGWs) in external field environments, we propose a low-noise monitoring array based on adjacent sensors with low reflectivity fiber Bragg grating (FBG). We analyze the interference signal models for adjacent FBG sensors, and based on them, a noise suppression method by using adaptive filter input is constructed. Then we simulate the noise suppression effect of the proposed algorithm under different noise conditions. Finally, we deploy the low-noise OPGW transmission line galloping monitoring system based on low reflectivity FBGs in China's western autonomous prefecture with a 220 kV transmission line. The experimental results show that, after adaptive filtering using adjacent sensors, the average noise power spectral density is reduced by 6.5 dB, and the algorithm optimizes the monitoring intensity spectrum. Oscillation events of about 100 m can be clearly observed within the monitoring interval. It creates certain conditions for further improving the typical event classification data processing and pattern recognition database for OPGWs and demonstrates promising prospects for engineering applications. [ABSTRACT FROM AUTHOR]