Impacts of flexible obstructive working environment on dynamic performances of inspection robot for power transmission line

The rigid-flexible coupling dynamic modeling and simulation of an inspection robot were conducted to study the influences of the flexible obstructive working environment i.e. overhead transmission line on the robot＇s dynamic performance. First, considering the structure of the obstacles and symmetrical mechanism of the robot prototype, four basic subactions were abstracted to fulfill full-path kinematic tasks. Then, a multi-rigid-body dynamic model of the robot was built with Lagrange equation, whil^e a multi-flexible-body dynamic model of a span of lin~ was obtained by combining finite element method （FEM）, modal synthesis method and Lagrange equation. The two subsystem models were coupled under rolling along no-obstacle segment and overcoming obstacle poses, and these simulations of three subactions along different spans of line were performed in ADMAS. The simulation results, including the coupling vibration parameters and driving moment of joint motors, show the dynamic performances of the robot along ftexibile obstructive working path： in flexible obstructive working environment, the robot can fulfill the preset motion goals; it responses slower in more flexible path; the fluctuation of robot as well as driving moment of the corresponding joint in startup and brake region is greater than that in rigid environment; the fluctuation amplitude increases with increasing working environment flexibility.

High Precision Ultrasonic Guided Wave Technique for Inspection of Power Transmission Line

Due to the merits of high inspection speed and long detecting distance, Ultrasonic Guided Wave（UGW） method has been commonly applied to the on-line maintenance of power transmission line. However, the guided wave propagation in this structure is very complicated, leading to the unfavorable defect localization accuracy. Aiming at this situation, a high precision UGW technique for inspection of local surface defect in power transmission line is proposed. The technique is realized by adopting a novel segmental piezoelectric ring transducer and transducer mounting scheme, combining with the comprehensive characterization of wave propagation and circumferential defect positioning with multiple piezoelectric elements. Firstly, the propagation path of guided waves in the multi-wires of transmission line under the proposed technique condition is investigated experimentally. Next, the wave velocities are calculated by dispersion curves and experiment test respectively, and from comparing of the two results, the guided wave mode propagated in transmission line is confirmed to be F（1,1） mode. Finally, the axial and circumferential positioning of local defective wires in transmission line are both achieved, by using multiple piezoelectric elements to surround the stands and send elastic waves into every single wire. The proposed research can play a role of guiding the development of highly effective UGW method and detecting system for multi-wire transmission line.

Dynamic Balance Control Based on an Adaptive Gain-scheduled Backstepping Scheme for Power-line Inspection Robots

This paper presents an adaptive gain-scheduled backstepping control(AGSBC) scheme for the balance control of an underactuated mechanical power-line inspection(PLI) robotic system with two degrees of freedom and a single control input.First, a nonlinear dynamic model of the balance adjustment process of the PLI robot is constructed, and then the model is linearized at a nominal equilibrium point to overcome the computational infeasibility of the conventional backstepping technique. Second, to solve generalized stabilization control issue for underactuated systems with multiple equilibrium points,an equilibrium manifold linearized model is developed using a scheduling variable, and then a gain-scheduled backstepping control(GSBC) scheme for expanding the operational area of the controlled system is constructed. Finally, an adaptive mechanism is proposed to counteract the impact of external disturbances. The robust stability of the closed-loop system is ensured by Lyapunov theorem. Simulation results demonstrate the effectiveness and high performance of the proposed scheme compared with other control schemes.

Prototype Monitoring System for Power Line Inspection by Means of a PandaBoard

The national energy supplier （Eskom in South Africa） supplies electricity through thousands-of-kilometers of overhead power lines. The current methods of inspection of these overhead power lines are infrequent and expensive. In this paper, the authors present the development of a prototype monitoring system for power line inspection in South Africa. The developed prototype monitoring system collects data （information） from the overhead power lines, is remotely accessible and fits into a power line robot. The prototype monitoring system makes use ofa PandaBoard （SBC） with GPS receiver and 5 MP camera to collect data. Hardware fatigue is the biggest problem faced on the overhead power lines and is captured by means of the 5 MP camera and is displayed on a website hosted by the PandaBoard via Wi-Fi. The monitoring system has low power consumption, is light weight, compact and easily collects data. The data obtained from the prototype monitoring system was satisfactory and provides an improved solution for monitoring power lines for Eskom in South Africa.

Hand-eye-vision based control for an inspection robot's autonomous line grasping

In order to ensure that the off-line arm of a two-arm-wheel combined inspection robot can reliably grasp the line in case of autonomous obstacle crossing,a control method is proposed for line grasping based on hand-eye visual servo.On the basis of the transmission line's geometrical characteristics and the camera's imaging principle,a line recognition and extraction method based on structure constraint is designed.The line's intercept and inclination are defined in an imaging space to represent the robot's change of pose and a law governing the pose decoupling servo control is developed.Under the integrated consideration of the influence of light intensity and background change,noise(from the camera itself and electromagnetic field)as well as the robot's kinetic inertia on the robot's imaging quality in the course of motion and the grasping control precision,a servo controller for grasping the line of the robot's off-line arm is designed with the method of fuzzy control.An experiment is conducted on a 1:1 simulation line using an inspection robot and the robot is put into on-line operation on a real overhead transmission line,where the robot can grasp the line within 18 s in the case of autonomous obstacle-crossing.The robot's autonomous line-grasping function is realized without manual intervention and the robot can grasp the line in a precise,reliable and efficient manner,thus the need of actual operation can be satisfied.

Steady-state voltage-control method considering large-scale wind-power transmission using half-wavelength transmission lines

Half-wavelength transmission can transmit large-scale renewable energy over very long distances.This paper proposes an improved steady-state voltage-control method for half-wavelength transmission systems considering largescale wind-power transmission.First,the unique voltage characteristics of half-wavelength lines are deduced based on the distributed parameter model.In the secondary voltage-control level,reactive power-transmission limits of half-wavelength lines are introduced as another control objective except for tracing the pilot bus voltage reference.Considering the uncertainty and fluctuation of wind power,the overvoltage risk-assessment method of half-wavelength lines is presented to determine specific voltage-control strategies.Simulation results demonstrate that the proposed voltage-control method delivers superior tracking performance according to a voltage reference value and prevents the overvoltage risk of halfwavelength lines effectively in different wind-power penetrations.

Prototype Line Crawler for Power Line Inspection

In South Africa, electricity is supplied through thousands-of-kilometers of overhead power cables, which is owned by Eskom the national energy supplier. Currently monitoring of these overhead power cables are done by means of helicopter inspection flights and foot patrols, which are infrequent and expensive. In this paper, the authors present the design of a prototype power line crawler （inspection robot） for the monitoring of these overhead power lines in South Africa. The designed prototype power line crawler is capable of driving on the wire, balancing on the wire and is capable of maneuvering past certain obstacles found on the overhead power cables. The prototype power line crawler is designed to host a monitoring system that monitors the power line as the inspection robot drives on it. Various experimental tests were performed and are presented in this paper, showing the capability of performing these tasks. This prototype inspection robot ensures a platform for future development in this area.

Variable universe fuzzy control of walking stability for flying‐walking power line inspection robot based on multi‐work conditions

To address complex work conditions incredibly challenging to the stability of power line inspection robots,we design a walking mechanism and propose a variable universe fuzzy control(VUFC)method based on multi‐work conditions for flying‐walking power line inspection robots(FPLIRs).The contributions of this paper are as follows:(1)A flexible pressing component is designed to improve the adaptability of the FPLIR to the ground line slope.(2)The influence of multi‐work conditions on the FPLIR's walking stability is quantified using three condition parameters(i.e.,slope,slipping degree and swing angle),and their measurement methods are proposed.(3)The VUFC method based on the condition parameters is proposed to improve the walking stability of the FPLIR.Finally,the effect of the VUFC method on walking stability of the FPLIR is teste.The experimental results show that the maximum climbing angle of the FPLIR reaches 29.1°.Compared with the constant pressing force of 30 N,the average value of slipping degree is 0.93°,increasing by 35%.The maximum and average values of robot's swing angle are reduced by 46%and 54%,respectively.By comparing with fuzzy control,the VUFC can provide a more reasonable pressing force while maintaining the walking stability of the FPLIR.The proposed walking mechanism and the VUFC method significantly improve the stability of the FPLIR,providing a reference for structural designs and stability controls of inspection robots.

A Data Driven Security Correction Method for Power Systems with UPFC

The access of unified power flow controllers(UPFC)has changed the structure and operation mode of power grids all across the world,and it has brought severe challenges to the traditional real-time calculation of security correction based on traditionalmodels.Considering the limitation of computational efficiency regarding complex,physical models,a data-driven power system security correction method with UPFC is,in this paper,proposed.Based on the complex mapping relationship between the operation state data and the security correction strategy,a two-stage deep neural network(DNN)learning framework is proposed,which divides the offline training task of security correction into two stages:in the first stage,the stacked auto-encoder(SAE)classification model is established,and the node correction state(0/1)output based on the fault information;in the second stage,the DNN learningmodel is established,and the correction amount of each action node is obtained based on the action nodes output in the previous stage.In this paper,the UPFC demonstration project of NanjingWest Ring Network is taken as a case study to validate the proposed method.The results show that the proposed method can fully meet the real-time security correction time requirements of power grids,and avoid the inherent defects of the traditional model method without an iterative solution and can also provide reasonable security correction strategies for N-1 and N-2 faults.

EDLine与改进光流法线路异物智能检测

为提高无人机电力故障巡检效率,提出一种结合边缘绘制线(edge drawing line,EDLine)特征提取算法与改进光流法的输电线路异物智能检测方法。鉴于背景纹理对航拍图像的影响,研究一种基于矩阵的线段融合算法以解决EDLine线段检测的断续问题,根据多特征约束提取输电线路区域。为有效识别异物,利用动量因子改进光流算法迭代收敛速度,根据光流信息检测异物故障。对无人机巡检图像的测试结果表明,该方法在复杂背景或异物不明显时均可有效检测出异物。提出检测算法准确度高、鲁棒性强,保证巡检的时效性。

Minimum Curvature Design of Three-Element Centripetal-turbine Hydrodynamic Torque Converters

The influence of streamline bending inertia force on power loss is investigated.In order to analyze the combined effect of the inertia force and the path on the power loss,the accumulation effect expression of the inertia force on its path is derived.The calculation result shows that the accumulation effect of the unit inertia force on its path depends merely upon the velocity magnitude and the path scroll angle.As long as they are given,the accumulation effect is a constant and independent of the intermediate path.An important conclusion drawn is that the maximum inertia force rather than its accumulation effect plays a predominant role in the power loss.Thus,a new design method,minimum streamline curvature method,is proposed.Fluid particle movement inside a hydrodynamic torque converter can be regarded as curved movement on the circular surface and decomposed into a meridional component and a circumferential component.Each meridional streamline is designed to be close to a circular arc,while each torus streamline is constructed with a circular arc and a straight line segment.Based on the meridional streamline equation,the torus streamline equation and a streamlined thickness function,a blade surface equation of three-element centripetal-turbine hydrodynamic torque converter can be obtained.

基于PLC构建电力巡检机器人自动化控制系统

该文对电力巡检机器人的自动化控制系统进行以PLC为基础的设计,提升电力调度的效率与安全性。基于PLC构建电力巡检机器人自动化控制系统总体架构,通过上位机接收操纵台传递的操作者信息以及下位机传递的温度、角度等状态信息,通过OPC通信程序将指令下发至下位机,下位机依据上位机下达指令,通过PID驱动控制器完成电力巡检机器人运动控制,利用模糊C均值聚类方法判别电力巡检机器人故障,将结果实时传送到上位机操纵台的显示器,及时反馈机器人的工作状态。实验结果表明,该系统可以控制机器人完成电力巡检,该系统应用后可有效检测机器人故障,使其具备优秀的避障能力,可实现上下位机实时通信。

高压输电线软体巡检机器人磁致动机制及PI滑模控制研究

为解决高压输电线刚性悬臂巡检机器人尺寸大、笨重、越障不灵活、效率低等问题,设计一种高压磁致动软体巡检机器人,利用载流线圈在高压直流环形磁场中受到的安培力驱动软体机器人以柔顺和蠕动方式高效灵活地跨越多种障碍物。对该机器人进行本体构型设计并分析其工作姿态,实现稳定巡检功能;对磁致动驱动器进行理论设计和分析,利用Comsol仿真软件对其所需驱动力进行仿真,验证理论的可实行性;通过拉格朗日法对高压磁致动软体巡检机器人进行动力学建模,构建系统动力学方程,获取机器人的关节角度、速度、加速度之间的关系;最后,通过MATLAB利用基于PI滑模控制法对简化后的高压磁致动软体巡检机器人动力学模型实行速度和角速度高精度追踪仿真。仿真结果表明:在滑模控制下,角度在1.5 s追踪上理想信号,角速度在0.3 s后追上理想信号,证明基于PI的滑模控制器能够实现对高压磁致动软体巡检机器人的有效控制。

变电站二次设备全向巡检机器人精确定位与作业辨识

通过巡检机器人进行变电站二次设备的监测是提升电力设备自动化、智能化管理的重要方式,有利于保障电力工程设备的安全运行。文中开发了一种用于变电站二次设备自动化巡检的Mecanum轮式全向移动机器人,其具备自主导航定位与作业辨识的能力,可极大提升设备巡检效率及保护压板状态识别准确性。通过Mecanum轮的驱动方式实现巡检机器人在狭窄作业环境下的灵活运动与姿态调整,通过多轨道升降平台实现对350~1 800 mm高度范围内的二次设备及压板的图像采集与状态辨识。机器人采用基于激光雷达的即时定位与地图构建(simultaneous localization and mapping,SLAM)导航方法进行自主定位导航,并结合基于视觉的路径提取与跟踪算法进行姿态位置修正,实现在待测点位置的精确定位。同时,提出了基于颜色辨识的图像排列与状态辨识方法,针对二次设备保护压板连通状态进行识别和判断。实验结果表明,研制的变电站二次设备巡检机器人可以实现自主导航与位置精确定位,在路径跟踪过程中最大偏角和偏距分别为±3°和±8 mm。结合机器视觉与颜色辨识的压板辨识方法可以准确识别压板状态,识别准确率大于95.80%,有助于提升机器人自动化的电力巡检作业水平。

激光雷达探测输电走廊安全风险研究现状

输电走廊环境监测和风险预警是电网防灾抗灾的重要研究内容。在激光雷达、物联网、无人机及计算机技术的发展与推动下,利用各种新型遥感监测与巡检手段进行输电走廊大范围、智能化巡检成为重要发展趋势。综合多种监测数据的线路安全风险评估与灾害预警,成为智能电网建设工作的研究热点之一。本文系统论述了应用激光雷达技术进行输电走廊安全风险探测的研究现状与发展趋势,分析了激光雷达在输电线路安全风险探测中的优缺点,讨论了激光雷达输电线路巡检和监测数据在输电线路安全风险评估预警中所面对的问题与挑战。

输电线路清障飞行机器人双行走轮同步控制

传统架空输电线路异物清除作业无人机易受环境影响,作业困难且存在较多扰动等问题。基于此本文设计一种高空作业无人机挂线行走控制机构解决该问题。首先,根据输电线路环境与无人机作业模式,设计挂线行走机构,减弱高空作业时对无人机所受飞行作业扰动的影响;其次,针对清障机器人双行走轮转速同步存在误差问题,提出一种基于反向传播–比例积分微分(back propagation-proportional-integral-differential,BP-PID)主从融合偏差耦合的电机同步控制策略。通过仿真与实物实验验证表明,本文提出的挂线作业无人机双行走轮同步控制算法可有效解决电机因负载导致的转速不稳定以及高空作业无人机受环境扰动的问题。

可变重心线路巡检机器人摆振分析及抑制

针对野外输电线巡检机器人(power transmission line inspection robot,PTLIR)受自然风影响出现的机身摆动问题,提出一种在机器人的可变重心箱体中加装摆式动力吸振器(dynamic vibration absorber,DVA)的摆振抑制策略。描述了输电线系统与巡检机器人加装摆式动力吸振器的结构特点。基于Davenport风速谱与输电线系统的特点建立了风扰动模型。分析了机器人行走对输电线的影响,建立了简化后风扰动影响下机器人摆动的动力学模型,仿真了抑振前机器人在风扰动影响下的风振响应;基于拉格朗日方程建立了加装动力吸振器优化后的巡检机器人动力学模型,并完成了吸振器的参数设计。通过仿真不同风速下机器人的风振响应,验证所提出的振动抑制策略的有效性。基于改进结构下的巡检机器人样机,开展了室内风扰动试验。结果表明,所提出的吸振器抑振策略可在一定程度上抑制机器人的机身摆动,提高工作稳定性。该研究过程对其他摆式结构设备的振动抑制具有一定的参考价值。

输电线路断股修复机器人自动上/下线飞行跟踪控制

电力系统中的输电线路具有分布广和跨越大等特点,确保其安全和稳定运行尤为重要。现有的输电线路断股修复任务通过人工或爬线机器人完成,存在作业风险高、机器人上线难度大等问题。针对此文章提出一种可以通过飞行挂线完成输电线路断股修复任务的飞行机器人,设计自适应模糊自抗扰(adaptive fuzzy active disturbance rejection control, AFADRC)控制器,确保机器人能够实现自动飞行上/下线。仿真结果表明,该机器人在提高输电线路断股修复效率和降低人工成本方面表现出色,同时也提高了作业的安全性。

220 kV输变电工程线路施工技术分析

电力工程和建设项目有着很大的区别,为了保证输电线路的正常运转,必须对输变电工程线路施工技术进行讨论和研究,并对技术的保障措施进行归纳,保证建设的高效进行。与此同时,在企业的经营方式上,建立健全管理机制、检查制度,加大技术研发的投入,以此来提高企业的日常运营和维修工作的效率和技术水平。因此,该文着重对220 kV输电线路的建设中应注意的问题进行探讨。

基于视觉与激光雷达的输电线路无人机自动化巡检控制

为了使无人机快速到达指定位置,提高输电线路巡检效率,该文提出了基于视觉与激光雷达的输电线路无人机自动化巡检控制方法。利用光流传感器获取无人机巡检速度信息,通过激光雷达与IMU分别确定无人机高度信息及姿态信息,采用扩展卡尔曼滤波器对各传感器数据融合,完成无人机巡检速度的预估,根据多传感器数据融合结果,设计基于PID的串联双环控制器,实现无人机巡检定高、定点位置控制。实验结果表明,该方法可实现多传感器数据融合,降低无人机巡检干扰,使其以相对平稳速度巡检;可实现无人机巡检控制,X、Y方向上的位置曲线与实际结果基本一致,位置误差较小;巡检过程中,无人机仰俯角、横滚角误差低于1°。