Design And Implementation Of A Power Line Inspection Robot For The Non-destructive Testing Of Overhead Aluminum Conductor Composite Core Wires

Aluminum conductor composite core(ACCC)wire,as a new type of conductor with good tensile strength and poor shear strength,has been widely used in power grid globally.The composite core in the ACCC wire is easy to be damaged in non-standard construction processes,which causes potential safety hazard in power system.In recent years,breakage accidents caused by damage of the composite cores have occurred frequently,which seriously threaten the safety of power grid operation.Due to the limitation of the volume and weight of the non-destructive testing(NDT)equipment,the existing inspection robots cannot detect the potential defects inside the ACCC wires effectively.Therefore,a new type of inspection robot for ACCC wires is in urgent demand in engineering applications.In this paper,the design of a novel inspection robot based on digital radiography is introduced,to solve the problem of the NDT of overhead ACCC wire.The proposed robot is in a form of wrapped structure for the detection of the single wire,equipped with a portable X-ray NDT system.The robot can carry out the NDT automatically,in the working space of line ends within 30 m,to detect the potential defects caused by non-standard constructions.The locations of suspected defects can be got by the robot system for later reinforcement and maintenance.The robot body is in a form of wrapped structure,with a baffle that can be locked on one side to facilitate installation.The NDT system based on digital radiography is carried by the robot,and the ray from the X-ray generator goes up through the ACCC wire to the digital radiography panel.The moving system enables the robot to move on the wires and cross obstacles in the working space,and ANSYS and ADAMS are used for simulation and optimization.The vibration reduction control system is composed of a stability control mechanism based on the hammer and a logarithmic stability control method,which ensures the robot better anti-disturbance stability and improves the quality of detection imaging.The control system of the inspection robot has the redundant backup in hardware design,such as the controller,power system and communication system,which can improve the reliability of the control system.The software modules of the control system include image acquisition and preprocessing,imaging definition evaluation,and parallel task scheduling programs,which can improve the efficiency and automation level of the NDT system.The human-machine interaction system includes the user terminal and the vibration feedback system,which improves the immediacy of operation.In order to verify the operation effect of the robot,the experimental verification research on the prototype is carried out.The lab experiments are conducted to test the motion performance such as moving,obstacle crossing and climbing,as well as the measurement and control performance of the vibration reduction control system,NDT system and positioning system.The experimental results show that the maximum climbing angle is 35 degrees when the robot is climbing the wire without obstacles,and the maximum climbing angle decreases to25 degrees when the robot is climbing the wire with a vibration damper.The oscillation stability speed of the robot with the vibration reduction control system increases by 12.4% and the oscillation peak decreases by 15.6% on average.In the operation conditions of robot starting and stopping intermittently,the positioning accuracy will be affected by the random errors caused by the skidding,and the average relative positioning accuracy in the environment of small wire angle,medium wire angle and large wire angle is 0.4%,0.2% and 0.6% respectively.In the field test,all parts of the robot operated normally.The average detection time of a single frame is 5.9s,which is 38.5% less than that of the single thread scheduling before optimization.The pass rate of detection image is 99.8%.The experimental results prove that the proposed robot meets the requirements of practical use and solves the problem of the NDT of the overhead ACCC wires successfully.