Fig. 1. Schematic diagrams of gallery GIL. (a) GIL layout of pipe gallery; (b) internal structure of GIL interval

Fig. 2. Vibration mechanism and numerical modeling flowchart of GIL. (a) Vibration generation process; (b) numerical modeling process

Fig. 3. Boundary conditions and finite element calculation results of GIL

Fig. 4. Physical test platform of prototype GIL

Fig. 5. Vibration waveform on GIL surface under 4500 A current. (a) Normal conditions; (b) mechanical defects

Fig. 6. Layout of 1550 nm fiber optical path

Fig. 7. Optical antenna design. (a) ZEMAX optical simulation; (b) structural design

Fig. 8. Diagram of balanced detector

Fig. 9. Test platform of optical beat signals

Fig. 10. Beat frequency vibration signal test

Fig. 11. Overall design of vibration signal processing

Fig. 12. Demodulation algorithm block diagram

Fig. 13. Demodulation effect of PZT mechanical vibration signal

Fig. 14. Frequency response curve of aluminum alloy

Fig. 15. LDV application test on prototype GIL platform

Fig. 16. LDV application on field pipe gallery GIL project. (a) Application results; (b) experimental results