Study On Transmission Line Icing-thickness Detection Device Based On Laser Ranging

Icing of transmission lines can cause great harm to the mechanical and electrical performance of transmission lines,which can lead to serious accidents such as trip,disconnection and tower collapse.In order to avoid the occurrence of ice disaster of transmission line,it is necessary to carry out a fast,effective and accurate measurement of icing condition,especially the icing thickness.In view of the shortcomings of traditional transmission line icing detection methods in dense fog,this thesis proposes a new method based on laser ranging to detect icing thickness of transmission lines.In this method,cross section of icing conductor in dense fog is illuminated by collimated laser.Measuring distance and corresponding rotation angle are obtained individually by distance measuring module and goniometer.And then wire icing thickness is obtained by geometric iteration.Firstly,thesis introduces measurement principle of detection device,deduces calculation method of icing thickness and critical condition of measurement.Secondly,to determine laser wavelength of detection device,532 nm,635nm,808 nm and 980 nm four kinds of laser wavelength are selected,and laser transmission characteristics in dense fog and reflection characteristics on different icing surfaces are discuss.Then,to improve the measurement accuracy,laser beam divergence angle is optimized by designing laser collimating system.Also,to complete detection device,the laser transmitting power,receiving device,ranging module and goniometer are determined.In this case,the maximum measurement distance of the detection device in different measurement environment is analyzed.Finally,glaze,mixed-phase and rime icing are simulated in artificial climate chamber,and ice thickness are measured in dense fog by using detection device and vernier caliper,respectively.And Measure performance of detection device is validated.Following conclusions can be drawn from the above work:With the increase of fog concentration,laser transmittance decreased,decreasing trend began very urgent then slow down,and the larger wavelength,the more laser transmittance decreases.When fog concentration is low,laser transmittance increases with the increase of wavelength.When fog concentration is high,laser transmittance decreases with the increase of wavelength.Under the same fog concentration,laser transmittance increases with the decrease of temperature,and the smaller wavelength,the larger laser transmittance increases.With the change of the ice type from glaze to rime,the average of BRDF increase,and reflection capacity of ice surface enhance.Because of glaze and mixed phase reflection law close to specular reflection,BRDF reach the peak at receiving angle equal to angle of incidence is.And with the increase of incident angle increases,the peak value of BRDF increases.For the same ice surface,with the increase of laser wavelength,reflection performance increases first and then decreases.With the increase of incidence angle,backward BRDF decreases.With the increase of the transmittance,the maximum measurement distance of detector increases rapidly.When measurement target is rime,maximum measurement distance is far than glaze's.When transmittance are less than 0.78m-1 or 0.85m-1,maximum measurement distance of glaze or rime are greater than the visibility.in the fog.When transmittance is 0.71m-1 and measurement distance is 2.5m and 5m,less than the maximum measuring distance,detection device can accurately measure the rime,and the maximum deviation is 0.28 mm and-0.51 mm respectively.And maximum deviation of mixed phase was 1.68 mm and-1.06 mm,respectively.While measurement results of glaze is less than true value,and with the increase of measurement distance,deviation increases,and maximum deviation is-1.78 mm and-2.29 mm,respectively.