Research And Design Of Aeolian Vibration On-line Monitoring On Transmission Lines

The aeolian vibration of transmission line is easy to cause the destruction of power lines and fittings,which affects the stability and reliability of power system.With people's growing demand for electricity,the height of hanging point,the transmission capacity and distance of power lines also increase.All these make aeolian vibration occur more easily.The damage caused by aeolian vibration comes from long-term accumulation and it has a strong concealment,so it is impossible to observe the damage directly.How to accurately monitor the state of overhead transmission line is very important.At present,the commonly used method is to adopt the displacement sensor to monitor the breeze vibration,but it has the problem of weak ability to resist electromagnetic interference,and it is difficult to measure the small vibration.A kind of vibration monitoring device is urgently needed to the power sectors,which can effectively avoid electromagnetic interference and has characteristics of easy installation and high measurement accuracy.This thesis does an research on the cause and the main affect factors of aeolian vibration on the basis of an analysis on current studies of the aeolian vibration online monitoring home and abroad,and analyzes the principle and method of measurement of aeolian vibration,emphatically introduces the calculation of dynamic bending strain while the wires vibrating.The data processing method of the on-line monitoring of aeolian vibration is studied as well.Three methods of the least-squares,fast Fourier transform and FFT based on wavelet de-noising are introduced and compared to lay a theoretical foundation for improving the accuracy of monitoring system.The overall architecture of the online monitoring system is briefly described in this article.A vibration monitoring unit is designed based on acceleration sensor.In this unit,the vibration acceleration information is acquired by an acceleration sensor and the processed data is uploaded to the monitoring station by a 2.4G wireless communication module to ensure the stability of information transmission.Apart from that,a power supply protection circuit is added to make the vibration monitoring unit work continually under bad environment.The structure of fully enclosed aluminum casing is used to realize the equipotential operation,which can avoid the direct contact between the sensor and the wire so that the high voltage of the line could not enter into the circuit board.The wavelet transform can be adopted to denoise the vibration signal to improve the accuracy of information processing.And then the amplitude and frequency of vibration would be get through the algorithm of FFT,the dynamic bending strain of the wire is calculated further more.The software design of wireless communication module ensures that the vibration monitoring unit and the monitor sub station can communicate in real-time and accurately.In this paper,the the accuracy and stability of the vibration monitoring unit is tested by a platform vibrator.The experimental results show that the measured data is reliable,and the time-domain amplitude and frequency errors are less than 3%.