Transmission Line Maintenance Research Articles

A prototype telerobotic platform for live transmission line maintenance: Review of design and development

This paper reports technical design of a novel experimental test facility, using haptic-enabled teleoperation of robotic manipulators, for live transmission line maintenance. The goal is to study and develop appropriate techniques in repair overhead power transmission lines by allowing linemen to wirelessly guide a remote manipulator, installed on a crane bucket, to execute dexterous maintenance tasks, such as twisting a tie wire around a cable. Challenges and solutions for developing such a system are outlined. The test facility consists of a PHANToM Desktop haptic device (master site), an industrial hydraulic manipulator (slave site) mounted atop a Stewart platform, and a wireless communication channel connecting the master and slave sites. The teleoperated system is tested under different force feedback schemes, while the base is excited and the communication channel is delayed and/or lossy to emulate realistic network behaviors. The force feedback schemes are: virtual fixture, augmentation force and augmented virtual fixture. Performance of each scheme is evaluated under three measures: task completion time, number of failed trials and displacement of the slave manipulator end-effector. The developed test rig has been shown to be successful in performing haptic-enabled teleoperation for live-line maintenance in a laboratory setting. The authors aim at establishing a benchmark test facility for objective evaluation of ideas and concepts in the teleoperation of live-line maintenance tasks.

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.

Robust motion control of live-line maintenance robot mechanical arm for high-voltage transmission line based on H∞ theory

To overcome the low operation efficiency, high labour-intensiveness and high risk in the artificial live-line replacement of insulator strings, a robot for overhead transmission line maintenance was developed. In order to suppress effectively the influences of disturbance signals and uncertainties on tracking precision and stability of the robot mechanical arm motion under high voltage and strong electromagnetic interference, this paper proposed a H∞ control theory-based robust trajectory tracking control method for the robot mechanical arm. Through layering robot control architecture, a dynamic model of mechanical arm basic motion was established by the Lagrange method combined with an armature voltage equation of the joint motor, and the unified dynamic model of mechanical arm different motion was obtained. On this basis, the state-space model of mechanical arm motion error was deduced under disturbances and uncertainties, and thus an H∞ control model for mechanical arm motion was constructed. Subsequently, the H∞ controller for the mechanical arm trajectory tracking control system was solved by linear matrix inequality (LMI) based on the established model, and the asymptotic stability of the mechanical arm motion control system was verified by selecting the appropriate Lyapunov function. The proposed method for such a controller was proved to be of good versatility, strong adaptability and sound expansibility. Finally, simulation results verified the effectiveness of the H∞ controller and field operation tests further validated the engineering practicability of such a control method in macro and micro aspects.

A State of the Art of Power Transmission Line Maintenance Robots

This paper dealt with a state-of-the-art maintenance robots for power transmission lines (PTL). The paper summarized the PTL maintenance robots that have been developed by eight major research institutions. The main features of the robot navigation were derived and classified through analysis of researches conducted by those institutions. The derived six main features were analyzed quantitatively and qualitatively through readiness level assessment. For this, system readiness level (SRL) was used to evaluate the readiness level of overall system. The SRL was obtained using technology readiness level (TRL) and integration readiness level (IRL). In addition, the readiness level for each feature was reviewed through statistical analysis using box and whisker plot. In conclusion, we confirmed the status and direction of research and development on PTL maintenance robots by analyzing conventional robots with respect to six main features.

Напряжения, наводимые на грозозащитном тросе воздушной линии электропередачи, как фактор риска. Часть 1

To ensure the staff safety under hot-line overhead transmission line (OTL) maintenance, as well as overhead ground-wire cable
 (OGWC) insulation integrity maintaining, by the example of three-phase 750 kV OTL has been presented an algorithm for
 calculation of voltages and electromotive forces (EMF) induced in this line’s OGWC by electric and magnetic fields (EF and MF)
 generated by OTL phases’ voltages and currents. Algorithms for calculation of line-to-earth voltages distribution along grounded
 at one end OGWC’ intervals have been given. It has been shown that the voltage induced at OGWC by EF of 750 kV OTL is much
 less than the voltage induced by this OTL’s MF. For single-phase short circuits modes has been presented an algorithm for
 selection of grounded at one end OGWC’ interval length by condition of respecting of voltage’s maximum permissible level on a
 spark gap shunting OGWC’s insulator set.

Research and Application of Transmission Line Differentiated Operation and Maintenance Scheduling Optimization Model

Aimed at resources shortage and extensive management of transmission line operation and maintenance, this paper proposes a differentiated operation and maintenance (DOM) method. This approach divides DOM strategy into basis strategy and criteria problem based strategy. An multi-objective DOM scheduling optimized model is presented, which contains three objective function including economy, safety and reliability. Based on the current electric power enterprise management requirements, personal safety factor is incorporated into safety objective function. Multi-objective Artificial Physics Optimization algorithm (MOAPO) based on feasible rules of law is used to solve the problem with an excellent diversity and high efficiency. The model is used to optimize yearly differentiated operation and maintenance scheduling in a certain area’s transmission system, the result verifies the feasibility of the model and method.

Electric systems failures produced by CG lightning in Eastern Amazonia

Operational records of power outages of the electric energy distribution systems in eastern Amazonia presented a large number of events attributed to lightning strikes, during the 2006 to 2009 period. The regional electricity concessionary data were compared to actual lightning observations made by SIPAM's LDN system, over two areas where operational sub systems of transmission lines are installed. Statistical relations were drawn between the monthly lightning occurrence density and the number of power outages of the electric systems for both areas studied. The results showed that, although with some delays between these variables peaks, the number of power disruptions has a tendency to follow the behavior of the lightning occurrence densities variations. The numerical correlations were positive and may be useful to the transmission lines maintenance crews at least for the Belém-Castanhal electricity distribution sub system. Evidence was found, that the SST's over certain areas of the Pacific and Atlantic Oceans, influence convection over the area of interest, and may help to prognosticate the periods of intense electric storms, requiring repair readiness for the regional electric systems.

A novel method for vegetation encroachment monitoring of transmission lines using a single 2D camera

The dangerous, overgrown vegetation/trees under high voltage transmission lines right-of-ways (ROWs) have caused severe blackouts/flashovers due to interference with power lines which leads to short circuiting among the conductors. Therefore, these dangerous encroachments are monitored periodically along the electrical distribution networks ROWs through visual inspection, or by airborne system. Each of these methods has its own attributes and limitations and have proved to be costly, time consuming and not much accurate. In these circumstances, it is necessary for the electrical utilities to review their vegetation management practices so as to avoid incidents of unintended encroachments. In tropical countries, overgrown vegetation is a common cause for power line failure. This paper proposes an innovative concept of utilizing a single camera for monitoring dangerous vegetation (trees, shrubs and plants, etc.) under transmission lines ROWs. The main focus is on using an imaging device (camera) integrated on each transmission pole to automate inspection for the vegetation encroachments endangering the transmission lines. These cameras are envisioned to be connected wirelessly to each other, forming a series of wireless camera networks that can be monitored remotely. A single camera mounted on power poles acquires images and sends them wirelessly to the base station. At base station, algorithm (software) trained by image processing and pattern recognition techniques is used to identify (height, depth, and width of encroached vegetation, etc.) excess vegetation encroachments within and outside ROWs. The performance evaluation of a real time developed test-bed scenario proves the feasibilities of integrating the method for transmission line maintenance.

Experimental study on location of lightning stroke on OPGW by means of a distributed optical fiber temperature sensor

abstract An electric anode with high pulsed current and a negative electrode are adopted to form a lightning impulse system with duration time of 200 ms for simulation of the lightning stroke process. The lightning stroke on the optical fiber ground wire (OPGW) is considered to be a heat release process at the lightning stroke position, and a distributed optical fiber temperature sensor (DOFTS) is employed to locate the lightning stroke. In the experiment, simulated lightning strokes with the quantity of electric discharge of 100 C and 200 C are generated respectively, but in the inner part of the OPGW the temperature increase captured by the DOFTS is just several degrees Celsius because of the heat-insulating property of the grease and jelly filled into the OPGW and the limit from spatial resolution of the DOFTS. Experimental results demonstrate that DOFTS has excellent potential for the maintenance of electric power transmission line and it is important to enhance the spatial resolution for further applications of DOFTS in engineering.

The Influence of Base Pre-Tilting on the Dynamic Properties of Angle Towers

As a significant bearing tower that is widely adopted in the electric transmission line, the angle tower is frequently found over-tilting in the inspection and maintenance of transmission lines. On the basis of the massive universal finite element software ANSYS, this study establishes a three-dimensional steel frame for the commonly used 500kV angle tower in the Inner Mongolian area, and analyzes the dynamic properties of angle towers while setting the base pre-tilting. It also conducts model analyses for the towers with or without base pre-tilting respectively, compares the frequency and mode of vibration, and paves way for further study of the setting of base pre-tilting and vibration response analysis.

Wire Suspension System Based on Fault Tree Analysis Running Condition Assessment

Overhead transmission lines is an important part in the power system and the lifeblood of the transmission system.Important element of the transmission line conductor suspension system namely conductor and insulator, hardware.This paper, by using the fault tree analysis method, establishes the mathematical model of the transmission line conductor suspension system running condition assessment, reliably evaluates the running status of system, find out the weak links and the problems of the various parts, for the evaluation and maintenance of overhead transmission line provide theoretical support.

Source and transmission line maintenance outage scheduling in a power system using teaching learning based optimization algorithm

In order to enhance the performance and lifetime of any equipment, maintenance is essential. The major power system components including generators and transmission lines require periodical maintenance and in this regard, the present work details Integrated Maintenance Scheduling (IMS) for the secure operation. The IMS problem has been formulated as a complex optimization problem that affects unit commitment and economic dispatch schedules. Most of the methodologies adopt decomposition approaches for the solution of IMS. In this work, Teaching Learning Based Optimization (TLBO) has been used as a prime optimization tool as it has been proved to be an effective optimization algorithm when applied to various practical optimization problems and its implementation is simple involving less computational effort. The methodology has been tested on standard test systems and it works well while including generator contingency. Numerical results comparison indicates that this method is a promising alternative for solving IMS problem.

Comparison of the Application of 3G and COFDM in UHV Transmission Lines Inspection

With the rapid construction of UHV power grid in China, the difficulty of transmission lines inspection and maintenance has increased dramatically. Thus it is urgent to adopt new technologies to replace the traditional manual mode of transmission lines inspection and maintenance. In this paper, the characteristics and applications in UHV transmission lines inspection of 3G and COFDM technology are analyzed and compared.

Development of Decision Support System for Protecting Distance between Power Lines and Trees

Resolving the contradiction between trees and power transmission lines in time is an important work to ensure the safety of transmission line operation. While it is difficult to decide the trees trimmed time during the transmission line operation and maintenance, the development of the management information system for protecting distance between transmission lines and trees, which is used to auxiliary predict the date of pruning, is a way to solve the problem. Collected attribute data of transmission lines and trees, the corresponding database is established. Therefore, Visual Basic 6.0 is adopted to develop the software system. Based on the spatial coordinates of line towers, conductors, and tree crown, the three-dimensional mathematical model is established to calculate the spatial distance between the conductor and tree crown. According to the mathematical model, the trees growth rate of year, month and day, respectively, and the protecting distance standard between conductor and tree crown, the system could calculate the actual spatial distance between conductor and tree crown, and auxiliary predict the pruning date.

The Overviews of Application of Three-Dimensional LiDar Technology in Operation and Maintenance of Overhead Transmission Lines in China

The paper briefly reviews the operational principles and commercialized conditions of airborne three-dimensional (3D) LiDar and terrestrial 3D LiDar. And then the representative functions of 3D LiDar that are developed for the operation and maintenance of overhead transmission lines (OTL) are described in detail. Besides, the problems associated with the process of applying 3D LiDar to OTL are analyzed. It is pointed out that it is necessary to make improvement to several aspects, including new functions development, standardization of application approaches and the simplification of data processing.

Atmospheric Corrosion Study on High-Voltage Overhead Power Transmission Line

Influence of atmosphere corrosion on conductor in the high-voltage overhead power transmission line has been paid more and more attention. This paper carries out experimental test research on atmosphere corrosion forms of aged conductor wires through metallographic analysis, electron microscope scanning etc. technologies, analyzing the influence of corrosion on its mechanical performance, which has provided theoretical reference for operation and maintenance of the overhead power transmission line.

Reliability Parameters Forecasting for Transmission Lines Based on Principal Component Regression

It is the foundation for evaluating the reliability of transmission lines to obtain and analyze the original reliability parameters. However, these parameters depend on long- term statistic and calculation. In the case of lacking such parameters in a new project , this paper proposes a method of Principal Component Analysis to obtain the principal component of the impacting factors ,in which various factors affecting reliability parameters are taken into account. Through this method, we can use PCR to obtain the failure rate of the unknown transmission lines on the base of the known credible lines’ rates. The simulation results show that the proposed approach possesses higher forecasting accuracy and provides references for the power system dispatching departments and transmission lines maintenance departments.

A New Type Design of Lighting Current Strength Detection Sensor

The lightning current parameters are very important for the lightning-line monitoring, they can provide important raw data for the construction of power grids and lightning protection engineering, conducive to the maintenance of high voltage transmission lines. But also provide the objective basis of the lightning accident analysis and statistics of lightning law. In this paper, we have Investigated parts of the complex and diverse terrain characteristics of Guizhou Province, we plan to design a simple, economic, effective data acquisition system for lightning current, timely and accurate grasp of the local lightning. we have done some research on the measurement mechanisms of lightning current strength. First, a novel lightning current strength detection program is proposed, and then we have done a lot of tests on the program and depicted the related parametric curve. Last, we verify the linearity of this sensor.

Vegetation encroachment monitoring for transmission lines right-of-ways: A survey

With increasing blackouts owing to vegetation encroachments for transmission lines right-of-ways, it has become imperative for electric utilities to review their vegetation management practices to avoid incidents of un-intended encroachments. In this paper, advantages and limitations of existing techniques for inspecting transmission lines is presented. Regarding the clearance of un-intended vegetation for transmission lines right-of-ways, the surveillance of transmission lines is performed periodically through visual inspection, or by airborne system. The geographical information system (GIS) containing the geo-referenced data of assets, lands, wherefrom the transmission lines pass are essential tools for the improvement of transmission lines maintenance. Air-borne LiDAR scanners, videography, and aerophotogranometry are now available for surveillance applications. These tools, because of their accuracy in spatial resolution, can be applied to track not only invasions, but also monitor the vegetation surrounding the transmission lines right-of-ways. The paper discusses concept of utilizing multispectral satellite stereo images to recover 3D-digital elevation model (DEM) of transmission lines right-of-ways to identify dangerous vegetation that can strike the power lines to cause blackouts. Further, a new wireless multimedia sensor networks (WMSNs) based method is proposed which is cost effective, less time consuming and more accurate for the automated power line inspection against vegetation encroachments.

Safety risk management for electrical transmission and distribution line construction

Prior research has established that electrical contractors involved in the construction and maintenance of electrical transmission and distribution (T&D) lines are at extremely high risk of electrocution. The result of inadvertent contact with T&D lines often is death or severe injury that involves damage to internal organs, musculoskeletal disorders, neurological damages and severe burns. The Electrical Safety Foundation International has demonstrated that contact with overhead power lines has been the single largest cause of electrical fatalities over the last decade. To reduce this disproportionate injury rate, electrical contractors implement many strategies such as the use of rubber insulating equipment, and locking devices. Unfortunately, these strategies are often cost-prohibitive in certain construction and maintenance scenarios. Therefore, electrical contractors are faced with complex decisions that involve comparing the cost of injury prevention with the expected safety benefit. This paper presents research that objectively evaluated the risk associated with common T&D construction tasks and the effectiveness of specific injury prevention techniques. The research team then developed a decision support framework that provides electrical contractors with objective safety and cost feedback given specific project characteristics. The results indicate that many of the effective strategies implemented to reduce T&D electrical injuries are very costly (e.g., de-energizing lines). Consequently, under most conditions, the costs of injury prevention far outweigh the cost savings associated with the reduction of injury rates. The implication of these findings is that T&D electrical contractors must highly value the non-monetary benefits of injury prevention in order to improve safety in their sector.