Research On Detection Method Of Mechanical Looseness Of Land Cable Based On Optical Fiber Vibration

Land cables play a pivotal role in the process of urbanization in my country.The cable intermediate joint is one of the weaker links in the land cable,and its safe and stable operation provides an important guarantee for the land cable.The cable intermediate joint is affected by transportation,installation,external excitation,and long-term vibration under the action of large currents,and fatigue damage will occur,resulting in looseness and other abnormal vibration phenomena.In this paper,based on the physical structure of the 35 k V cable intermediate joint,the normal vibration and resonance vibration model of the cable intermediate joint and the vibration model under the loose state are established;the modal analysis of the cable intermediate joint is carried out to obtain its 15 th order natural frequency;the harmonic response is used Analytical method to determine the 6 resonance frequencies of the cable middle joint.Then,based on the principle of distributed optical fiber vibration sensing,the ANSYS finite element simulation software was used to detect and analyze the vibration of the cable middle joint under 50 Hz,100Hz normal vibration,376 Hz resonance and 50 Hz looseness;the cable middle joint was at376 Hz resonance and 50 Hz The amplitude in the state is about 3 orders of magnitude larger than the amplitude of the two normal vibrations,and the v ibration characteristics of each position in the loose state are basically the same.Compared with the resonance,there is no obvious vibration attenuation trend.Finally,based on the FFT algorithm,the cable intermediate connector is analyzed by algorith m,and its vibration characteristics in the frequency domain are obtained.Based on the wavelet packet algorithm,the vibration algorithm is analyzed,and the vibration characteristics of the cable intermediate connector in the time domain,frequency domain and energy are obtained.In this paper,through the analysis of the vibration of the cable middle joint under 50 Hz,100Hz normal vibration,376 Hz resonance and 50 Hz loose state,the time domain vibration characteristics of the three vibration states are obtained;based on the FFT algorithm and wavelet packet algorithm,the algorithm analysis of the cable middle joint,Obtained the frequency domain,time domain and energy vibration characteristics of the cable middle joint under the three vibration states,and then identified the three vibration states of the cable middle joint.The research results of this paper can provide theoretical support for the vibration analysis of cable middle joints in practice.