Application of Non-Contact Vibration Detection For Gas Insulated Transmission Line via Laser Doppler Vibrometer Technique
In this paper,a non-contact vibration detection method for gas insulated line(GIL)based on laser Doppler vi-brometer(LDV)technology is proposed.First,vibration frequency and amplitude distribution under normal and defect conditions are obtained by transient electromagnetic-structural coupled field finite element modeling and physical experiments.Besides measuring points on GIL surface and parameters of LDV system are also con-firmed.The 1550 nm fiber optical path component including narrow linewidth laser,optical transceiver,acous-to-optic modulator(AOM)and balanced detector is designed,and the optical beat signal which contains object movement information is successfully obtained.Vibration signal demodulation scheme based on digital orthog-onal and differential cross multiplication algorithm is developed.The mechanical vibration signals within frequency range 50 Hz‒20 kHz between 0.5‒20 m distance are acquired by proposed system.The developed system has been successfully applied to GIL prototype platform testing and on-site GIL inspections,effectively overcoming the shortcomings of contact-based accelerometers,such as installation difficulties,low detection efficiency,and poor accuracy.This has enabled non-contact vibration measurement for long-distance GIL equipment.
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