Applied Numerical Analysis. By C.F. Gerald. Pp. xii, 340. £3·60. 1970. (Addison-Wesley.)

Wireless sensor networks are becoming the technology of choice for sensing applications mostly due to their ease of installation and associated lower costs. This paper proposes a novel conceptual design for an application of wireless sensor technology for assessing the structural health of transmission lines and their implementation to improve the observability and reliability of power systems. A two-layer sensor network model is presented for overcoming the communication range limitations of smart sensors, and two operational modes for enhanced energy efficiency are introduced. Simulations integrating the output of the sensor network with an energy-management system were conducted, obtaining improvement in the security of the power system

Application of Sensor Network for Secure Electric Energy Infrastructure

On the vortex shedding forcing on suspension bridge deck

Fiber-optic sensing technology is best adapted to health monitoring and evaluation of power grids because of its immunity of electromagnetic interference, capabilities of multiplexing and distributed sensing, and tolerance to harsh environments. We review key fiber-optic sensing technologies, including fiber Bragg gratings, fiber-optic interferometers, optical time domain reflectometries, and their applications in three main parts of power grids, transformers, power towers, and overhead transmission lines, during the past 20 years. In particular, optical fiber composite overhead ground wire and optical phase conductor applied in power grids are the areas of great potential to go further. The perspectives of an intelligent fault diagnosis subsystem for power grids based on a fiber-optic sensing network are discussed, and related on-going work is described. The review shall be of benefit to both engineers and researchers in power grids and fiber-optic sensing.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-58/issue-7/072007/Review-on-fiber-optic-sensing-in-health-monitoring-of-power/10.1117/1.OE.58.7.072007.pdf

Review on fiber-optic sensing in health monitoring of power grids

Aerodynamics of nominally circular cylinders: A review of experimental results for Civil Engineering applications

Addressing an Urgent Challenge Probably no other large structure has as much of its mass in highly flexible form, and so continuously exposed to the forces of the wind, as does the modern transmission line. This makes the line susceptible to sustained cyclic conductor motions, which can take the form of vibration, galloping, or other types of movement. Because conductors are supported and supplemented by thousands of pieces of hardware, many opportunities for damage arise during these motions. Conductors and their auxiliaries are critical and expensive components that are difficult to inspect while lines are in service. Therefore, problems caused by conductor motion must either be anticipated and prevented during the design and construction stages or resolved at high cost after visible damage or motion has occurred.

EPRI Transmission Line Reference Book : wind-induced Conductor Motion.

A novel algorithm is developed in this paper for analyzing Aeolian vibration of a span of a single conductor with multiple dampers. The algorithm is characterized by a combination of an impedance transfer technique (ITT) and a forced vibration method (FVM). The ITT avoids singularities that may occur due to a conductor's very low bending stiffness with respect to its tension. On the other hand, the FVM can easily handle non-proportional damping (which is typical for the problem in concern) without having to solve a complex eigenvalue problem. In addition, the algorithm can easily accommodate a conductor's terminal flexibility as well as a damper's rotational effect that may exist due to its possible asymmetry. The algorithm is very efficient so that solution is almost instantaneous for most analysis problems. The algorithm has recently been implemented into a commercial Aeolian vibration analysis and design software-EPRI Vibration version 3.0.

An Efficient Algorithm for Aeolian Vibration of Single Conductor With Multiple Dampers

A novel add-on device, called a hybrid nutation damper (HND), is proposed to control galloping on both single and bundled conductors of overhead power lines. An HND employs a nutation damper (also called a tuned liquid damper) as an energy dissipator, and a tuned mass damper as the mechanism to transfer a conductor's plunge motion into a nutation damper's rotational motion. An HND is in principle effective for any type of galloping. It is particularly effective for a plunge galloping-the one most often observed in the field and existing control devices have difficulty handling. An HND is simplified as an equivalent two degrees-of-freedom model and is then incorporated into existing three degrees-of-freedom based, galloping software. A two-tiered procedure is established to optimize an HND's performance. Numerical examples show that an HND is invariably very promising in controlling galloping

Hybrid Nutation Damper for Controlling Galloping Power Lines

The power transmission conductor system consists of: the aluminum conductor, the steel-core supporting material, and the splice connector. The splice connector connects the aluminum conductor to form a continuing current transmission line. The splice connector region of a conductor system is more sensitive to material aging during service. This is due to the material discontinuity and the crimped connector's forming mechanism. The objective of this project is to develop a protocol to evaluate the integrity of a full tension single-stage splice connector (SSC) assembly operated at high temperature. The project focuses on thermal mechanical testing, thermal cycling simulation and the effective lifetime of the SSC system. The investigation indicates that thermal cycling temperature and frequency, conductor cable tension loading, and the compressive residual stress field within a SSC system have significant impact on SSC integrity and its associated effective lifetime. The developed governing equation and its application to assure the adequate service life of transmission lines are also discussed in the paper.

The Lifetime Estimate for ACSR Single-Stage Splice Connector Operating at Higher Temperatures

Due to the increase in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than those used for the original design criteria. This has led to the accelerated aging and degradation of splice connectors, which have been manifested by the formation of hotspots that have been revealed by infrared imaging during inspection. The implications of connector aging is twofold: 1) significant increase in resistivity of the splice connector (i.e., less efficient transmission of electricity) and 2) significant reduction in the connector clamping strength, which could ultimately result in separation of the power transmission line at the joint. Therefore, the splice connector appears to be the weakest link in the electric power transmission lines. This paper presents a protocol for integrating analytical and experimental approaches to evaluate the integrity of a full tension single-stage splice connector assembly.

John Chan

Papers

EPRI Transmission Line Reference Book : wind-induced Conductor Motion.

An Efficient Algorithm for Aeolian Vibration of Single Conductor With Multiple Dampers

Hybrid Nutation Damper for Controlling Galloping Power Lines

The Lifetime Estimate for ACSR Single-Stage Splice Connector Operating at Higher Temperatures

The Integrity of ACSR Full Tension Splice Connector at Higher Operation Temperature