| Hitherto,unmanned aerial vehicle(UAV)inspection has gain significant attention and widely applied in daily operation and maintenance of overhead transmission lines.At present,there still exists a great potential safety hazard in UAV inspection,since the distance between the patrol UAV and the power line is mainly according to visual inspection.Therefore,it is necessary to explore UAV ranging and corresponding route planning theory and technology.This paper builds a simulation model based on actual transmission lines,analyzes the influence of tower shielding effect on electric field measurement,and carries out adaptive analysis on UAV ranging based on the simulation results.A methodology for measuring the distance between UAV and transmission lines is proposed,with the combination of the effective value of electric field and the height of UAV.It is proposed to apply the different electric field thresholds to form a safety protection range for transmission lines of various voltage levels which is verified in the actual line.The influence of the installation position of the electric field sensor on the electric field measurement,the distortion effect of the electric field measurement and the calibration method are studied.The gradient descent algorithm is introduced and applied to solve the electric field distortion coefficient and correct the flight error of UAV.The actual electric field of 1000 k V ultrahigh voltage overhead transmission line is utilized to correct the measured electric field of the experimental UAV.The distance between the UAV and the transmission line is retrieved and verified.The path planning and its constraint conditions in UAV patrol task are analyzed.In the actual route,the flight path was planned for the UAV inspection corridor or tower mission,and the validity and rationality of the path were verified by the actual flight test.The obstacle avoidance strategy of UAV in inspecting the transmission line is proposed.This paper provides a reference for distance control,heading planning,height adjustment and electric field measurement of UAV in inspecting the transmission line,which is of great significance in engineering practice. |
