| Overhead transmission lines cover a wide area and mostly pass through the regions with bad natural environment and complex terrain,which brings new challenges to the transmission line safety inspection and monitoring technology in the new era.The airborne Li DAR(Light Detection and Ranging)system can quickly acquire high-precision and high-density Transmission Line 3D information-point cloud data,which has the advantages of high efficiency,wireless loss,non-contact,etc.,it has become the hot spot of transmission line intelligent inspection.Although domestic and foreign scholars have carried out a large number of Li DAR power inspection engineering experiments and theoretical research and made significant progress,there are still problems such as low accuracy of information extraction,data mining and application is not comprehensive enough.Therefore,the paper combines the theories and methods related to active remote sensing technology,electrical technology and meteorology to meet the requirement of Airborne Li DAR for power transmission line Operation Safety Monitoring,in order to improve the reliability and application value of Airborne Li DAR power inspection results,the key technologies such as fine extraction of transmission line,reconstruction of transmission line model,simulation of transmission line working condition and condition monitoring are studied.The main findings and conclusions are as follows:(1)Two kinds of precise extraction methods of laser point cloud transmission line are proposed.According to the spatial characteristics of transmission lines,two precise extraction methods of laser point cloud transmission lines are proposed,including the residual density clustering method of laser point cloud transmission line precise extraction model and the improved k-means clustering method of laser point cloud transmission line precise extraction.By transforming the 3D point cloud segmentation of transmission line into the 2D model residual clustering,the dependence of the extraction result on the continuity and integrity of point cloud is weakened,this method can effectively solve the problem of laser point cloud transmission line fine extraction under the background of data missing and point cloud noise.The experimental results show that the precision of the two methods is above 95%,and the residual density clustering method introduces the density clustering algorithm which does not need category number input and can recognize any shape cluster,with a high degree of automation,universal good characteristics;The improved K-MEANS clustering algorithm is based on the selection of initial sample points with distance constraints,the determination of the number of inflexion points and the automatic recognition of noise points,the utility model has the advantages of simple operation and anti-noise strength.(2)The parameter solving method of transmission line geometry model is improved.Point cloud data,model selection and parameter solution are the main factors that affect the reconstruction of 3D transmission line model.In this paper,the reconstruction accuracy of the laser point cloud transmission line model is improved through the discussion of model selection scheme and the improvement of parameter solution method,the experimental results show that the parabola-parabola equation proposed in this paper has high accuracy and efficiency for the reconstruction of the transmission line model in laser point cloud in wind bias environment,the existing linear-parabola and linear-catenary methods are suitable for the reconstruction of laser point cloud transmission line model without wind bias,and the linear-parabola equation is better The improved parameter solution method of random sampling consistency model has the advantages of both efficiency and precision.The minimum error of laser point cloud transmission line model reconstruction is 7.06 and the average error is 6.15 cm,the maximum error is 19.10 cm,which is consistent with the reconstruction accuracy of the laser point cloud model.(3)The simulation method of typical working condition of transmission line is established.Based on the static laser point cloud transmission line model and the mechanical mechanism of meteorological conditions acting on the transmission line,a simulation method of transmission line configuration under three typical working conditions of high temperature,icing and high wind was established,in order to verify the accuracy of transmission line shape simulation under the condition of no windage bias,there are some shortcomings such as low accuracy in obtaining the measured value and insufficient sample size of the reference value,a cross-validation method based on two-phase laser point cloud is designed to evaluate the simulation accuracy of power transmission lines.The results show that the two-phase laser point cloud cross-validation method is feasible and reliable.The maximum average error of the simulation is 0.036 m and the maximum medium error is 0.027,the maximum error is 0.171 m,which overcomes the disadvantages of low precision and low efficiency of traditional simulation.(4)The technical flow of monitoring the operation state of transmission line is formed.Combining the research contents of laser point cloud transmission line extraction,laser point cloud transmission line model reconstruction and laser point cloud transmission line operating mode simulation,based on the research of monitoring index and Grade Division,clearance distance monitoring method,ice thickness monitoring method and horizontal stress monitoring method,the technical flow of Operation Condition Monitoring of airborne laser point cloud transmission line is established.Based on the static laser point cloud data,the technique can realize the monitoring/detection of transmission line defects under the dynamic meteorological environment,and solve the technical problem that the static laser point cloud can not monitor the real-time operation of transmission line.Through the above research work,the accuracy of transmission line extraction and model reconstruction from static point cloud data is improved,and the transmission line shape simulation method under high temperature,high wind and typical icing conditions is established,the technical flow of transmission line safe operation state monitoring is improved,which provides research ideas and theoretical reference for the application of Li DAR Technology in transmission line inspection. |
PDF Full Text Request