Laser Doppler Vibrometry System and Angle Compensation Algorithm for GIS Vibration Detection

To realize reliability on-line vibration detection of gas-insulated switchgear (GIS), this paper designs a detection system based on a laser Doppler vibrometer (LDV). The system adopts a 1550 nm all-fiber structure, equipped with an integrated transceiver optical antenna and a balanced photodetector, which can effectively suppress background light noise and improve the signal-to-noise ratio. Meanwhile, it processes signals through a semi-digital quadrature demodulation algorithm. Aiming at the measurement deviation caused by the laser incident angle, the proposed angle compensation algorithm corrects the measured values under different pitch angles by calculating the included angle between the laser and the normal vector of the tank surface, significantly enhancing data accuracy. Laboratory test results show that the system can accurately detect the mechanical vibration signals of the GIS tank within a distance range of 0.1 m–18 m, and the measured frequency is consistent with the set vibration source frequency, verifying the effectiveness of the system design and the angle compensation algorithm.