High-voltage Electric Transmission Research Articles

Identification of top contributors to system vulnerability via an ordinal optimization based method

This paper presents a novel approach to identify top contributors to power systems failure when considering cascade failure events. Implementation of this approach can help for a better system understanding to system stakeholders, provide internal and external situational awareness to operators, and help as a diagnostic support tool. Given the few studies that concurrently consider cascade models with models for identifying top contributors to load shed, this paper presents a novel hybrid approach combining an evaluation phase – a cascade model together with an approximate evaluation of the damage induced (in terms of load shed) by a collapse event – and an ordinal optimization perspective, to identify top component failure contributors. The approach is implemented in the Italian high-voltage (380kV) electrical transmission network and results are compared against current topological measures of system vulnerability.

Characteristic Analysis of DS18B20 Temperature Sensor in the High-voltage Transmission Lines’ Dynamic Capacity Increase

Dynamic capacity increase in high voltage electric power transmission line is currently the most economical method for solving electric power transmission bottleneck nowadays. DS18B20 temperature sensor is applied to the dynamic capacity increase of high voltage transmission lines to measure the conductor temperature and ambient temperature. The paper is focused on the experiment of DS18B20 both in the laboratory and outside. From the result of the lab temperature measurement data analysis, using 4 DS18B20’s is the most suitable plan, considering both accuracy and economical efficiency. In the experiment outside, we get four groups of conductor (uncharged) temperature and four groups of ambient temperature. The data proved that DS18B20 has good stability, and small measurement error. It is suitable for measuring the temperature of conductor and ambient in dynamic capacity increase, and helpful to improve the accuracy of the calculation of capacity increasing.

Integration of Pipeline Operations Sourced with CO2 Captured at a Coal-fired Power Plant and Injected for Geologic Storage: SECARB Phase III CCS Demonstration

This paper presents a case study of the design and operation of a fit-for-purpose pipeline sourced with anthropogenic carbon dioxide (CO2) associated with a large-scale carbon capture and storage (CCS) Research & Demonstration Program located in Alabama, USA. A 10.2 centimeter diameter pipeline stretches approximately 19 kilometers from the outlet of the CO2 capture facility, located at Alabama Power Company's James M. Barry 2,657 - megawatt coal-fired electric generating plant, to the point of injection into a saline reservoir within Citronelle Dome.The CO2 pipeline has a 6.5 meter wide easement that primarily parallels an existing high-voltage electric transmission line in undulating terrain with upland timber, stream crossings, and approximately 61,000 square meters of various wetland types. In addition to wetlands, the route transects protected habitat of the Gopher Tortoise. Construction methods included horizontal drilling under utilities, wetlands, and tortoise habitat and ‘open cutting’ trenching where vegetation is removed and silt/storm-water management structures are employed to limit impacts to water quality and ecosystems. A total of 18 horizontal directional borings, approximately 8 kilometers, were used to avoid sensitive ecosystems, roads, and utilities.The project represents one of the first and the largest fully-integrated pulverized coal-fired CCS demonstration projects in the USA and provides a test bed of the operational reliability and risk management for future pipelines sourced with utility CO2 capture and compression operations sole-sourced to injection operations. An update on status of the project is presented, covering the permitting of the pipeline, risk analysis, design, construction, commissioning, and integration with compression at the capture plant and underground injection at the storage site.

Creating a Smarter U.S. Electricity Grid

This paper focuses on efforts to build what policymakers call the “smart grid,” involving 1) improved remote monitoring and automatic and remote control of facilities in high-voltage electricity transmission networks; 2) improved remote monitoring, two-way communications, and automatic and remote control of local distribution networks; and 3) installation of “smart” metering and associated communications capabilities on customer premises so that customers can receive real-time price information and/or take advantage of opportunities to contract with their retail supplier to manage the consumer's electricity demands remotely in response to wholesale prices and network congestion. I examine the opportunities, challenges, and uncertainties associated with investments in “smart grid” technologies. I discuss some basic electricity supply and demand, pricing, and physical network attributes that are critical for understanding the opportunities and challenges associated with expanding deployment of smart grid technologies. Then I cover issues associated with the deployment of these technologies at the high voltage transmission, local distribution, and end-use metering levels.

Identifying groups of critical edges in a realistic electrical network by multi-objective genetic algorithms

In this paper, an analysis of the vulnerability of the Italian high-voltage (380 kV) electrical transmission network (HVIET) is carried out for the identification of the groups of links (or edges, or arcs) most critical considering the network structure and flow. Betweenness centrality and network connection efficiency variations are considered as measures of the importance of the network links. The search of the most critical ones is carried out within a multi-objective optimization problem aimed at the maximization of the importance of the groups and minimization of their dimension. The problem is solved using a genetic algorithm. The analysis is based only on information on the topology of the network and leads to the identification of the most important single component, couples of components, triplets and so forth. The comparison of the results obtained with those reported by previous analyses indicates that the proposed approach provides useful complementary information.

Effects of neutral point reactors and series capacitors on geomagnetically induced currents in a high‐voltage electric power transmission system

Geomagnetically induced currents (GIC) are DC‐like currents compared to power transmission frequencies. Consequently, it may be possible to reduce the magnitudes of GIC by installing resistive components or series capacitors into a power grid. We simulate the effects of neutral point reactors and series capacitors on GIC in the Finnish 400 kV network. Reactors add an additional resistance to earthing leads of transformers, and series capacitors block the flow of GIC in transmission lines. The geoelectric field impacting the system is considered to be uniform. The use of reactors does not necessarily reduce the GIC risk. Although the installation of reactors tends to decrease GIC on the average, maximum GIC may even increase. Assuming a reactor at all stations results in a 50% reduction of the maximum GIC compared to the situation with no reactors. With up to four series capacitors, the maximum GIC is reduced by 40% when they are optimally located. However, even small changes in the topology of the grid can cause large changes in GIC. A combination of reactors and series capacitors could in principle provide a way to diminish the GIC risk. This study also emphasizes the difficulty of preventing GIC problems by these means.

Characterization of the fatigue properties of a hybrid composite utilized in high voltage electric transmission

The fatigue properties of a unidirectional carbon/glass/epoxy hybrid composite used as the load bearing member of the next generation high voltage transmission lines were evaluated. It was found that the composite showed a strong sensitivity to the amount of transverse loading when tested using the rotating beam method. These results indicate that the bearing stress at mechanical connections must be considered for effective fatigue life design. At the lowest stress amplitude evaluated in this research, the hybrid composite material exhibited run-out behavior. For the remaining stress amplitudes, the S–N behavior of the hybrid composite material was well described by a “Basquin type” power law relationship. It was also found that the composite exhibited a period of “wear-in” behavior in which the composites’ axial modulus increased substantially. This increase was attributed to a change in the alignment of the reinforcing fibers under the influence of an applied load.

Research on Performance of Resisting Foundation Displacement of High Voltage Electricity Transmission Tower in Mining Subsidence Area

The performance of resisting foundation displacement of a typical single return circuit transmission tower under all kinds of load conditions including foundation horizontal displacement, foundation vertical uneven downward displacement was analyzed by finite element modeling. Results showed that stability failure of single steel angle represents tower’s limit state under foundation displacement. And the corresponding foundation displacement limits were calculated. Results indicate that foundation pull condition is more dangerous than press condition. Under complex foundation displacement conditions, foundation horizontal displacement is primary factor leading to stability failure of towers. Under foundation press condition and pull condition, wind load is primary factor. Result also indicates that, tower does not fail when foundation displacements are smaller than 1.25% (under foundation press condition and pull condition) or 0.5% (under single foundation sink condition) of tower root distance.

Occupational exposure to electromagnetic fields and sex-differential risk of uveal melanoma

ObjectivesThe association between occupational exposure to electromagnetic fields (EMF) and the risk of uveal melanoma was investigated in a case–control study in nine European countries.MethodsIncident cases of uveal melanoma and...

Collapse and pull – down analysis of high voltage electricity transmission towers subjected to cyclonic wind

Bulk electricity transmission lines are linear assets that can be very exposed to wind effects, particularly where they traverse steep topography or open coastal terrain in cyclonic regions. Interconnected nature of the lattice type towers and conductors also, present complex vulnerabilities. These relate to the direction of wind attack to the conductors and the cascading failure mechanisms in which the failure of a single tower has cascading effects on neighbouring towers. Such behaviour is exacerbated by the finely tuned nature of tower design which serves to minimize cost and reserve strength at design wind speeds. There is a clear need to better quantify the interdependent vulnerabilities of these critical infrastructure assets in the context of the severe wind hazard. This paper presents a novel methodology developed for the Critical Infrastructure Protection Modelling and Analysis (CIPMA) capability for assessing local wind speeds and the likelihood of tower failure for a range of transmission tower and conductor types. CIPMA is a program managed by the Federal Attorney-General's Department and Geoscience Australia is leading the technical development. The methodology then involves the development of heuristically derived vulnerability models that are consistent with Australian industry experience and full-scale static tower testing results, considering isolated tower loss along with three interdependent failure mechanisms to give overall likelihoods of failure.

Causes of Raptor Admissions to a Wildlife Rehabilitation Center in Tenerife (Canary Islands)

We studied the causes of raptor admissions to the only wildlife rehabilitation center on the largest island of the Canarian Archipelago (Tenerife) over ten years (1998–2007). A total of 2611 birds of prey, belonging to nine falconiform diurnal raptor and four strigiform species, were admitted. The Eurasian Kestrel (Falco tinnunculus) and the Long-eared Owl (Asio otus) were the species most commonly admitted and jointly made up 85.6% of admissions. The most frequent causes of admission to the wildlife rehabilitation center were collisions (with cars, high-voltage electric transmission towers, etc.; 42.2%), starvation (5.1%) and entanglement in glue traps intended for rodents (4.7%). Poisoning and shooting were recorded for 2.4 and 1.5% of the birds admitted, respectively. Only collisions increased during the study period. A total of 1010 birds (44.4% of the total) were released to the wild following rehabilitation. We recommend more financial support for rehabilitation centers to develop detailed analytical diagnoses and rehabilitation services.

In-Cloud Icing in the Columbia Basin

Abstract On 24 November 2005, 11 lattice steel towers of a high-voltage electrical transmission line running along the edge of an escarpment were damaged by an accumulation of rime on overhead ground wires. Cold air pooling in the Columbia basin of eastern Washington several days before the failure led to the formation of low-level fog and low clouds with temperatures below freezing at the elevation of the transmission line. The liquid water content profile of the cloud formed by air rising over Badger Mountain north of Wenatchee, Washington, is estimated using the air temperature, dewpoint temperature, and air pressure as measured at Wenatchee in the Columbia River valley below the line. Cloud median volume droplet diameters are estimated using typical droplet concentrations. The validity of the computed liquid water content is determined by comparing the measured cloud-base heights at Wenatchee with the calculated cloud-base heights. The mass and density of ice accreted on the ground wires and conductors of the transmission line are modeled using assumed wind speeds at the top of the escarpment with the estimated cloud properties. Results are compared with the density and mass of an ice sample retrieved from the field. This event is compared with other modeled in-cloud icing events from 1973 to 2007 using the period of record of Wenatchee weather data. This paper illustrates an approach for estimating the severity of in-cloud icing on the wires of transmission lines subject to cloud liquid water contents that have been enhanced by the local terrain.

Environmental justice: A contrary finding for the case of high-voltage electric power transmission lines

Environmental justice is the consideration of whether minority and/or lower-income residents in a geographic area are likely to have disproportionately higher exposures to environmental toxins than those living elsewhere. Such situations have been identified for a variety of factors, such as air pollution, hazardous waste, water quality, noise, residential crowding, and housing quality. This study investigates the application of this concept to high-voltage electric power transmission lines (HVTL), which some perceive as a health risk because of the magnetic fields they generate, and also as esthetically unpleasing. We mapped all 345 kV and higher voltage HVTL in New York State and extracted and summarized proximate US Census sociodemographic and housing characteristic data into four categories on the basis of distances from HVTL. Contrary to our expectation, people living within 2000 ft from HVTL were more likely to be exposed to magnetic fields, white, of higher income, more educated and home owners, than those living farther away, particularly in urban areas. Possible explanations for these patterns include the desire for the open space created by the rights-of-way, the preference for new homes/subdivisions that are often located near HVTL, and moving closer to HVTL before EMFs were considered a risk. This study suggests that environmental justice may not apply to all environmental risk factors and that one must be cautious in generalizing. In addition, it shows the utility of geographical information system methodology for summarizing information from extremely large populations, often a challenge in epidemiology.

The Country and the Grassroots: Rural action for local control of energy policy and development

This paper presents an ongoing ethnographic study of a coalition of grassroots groups in central New York State that organized in the spring of 2006 to protest the construction of a 110 foot, 400,000 volt, 192-mile long direct current high voltage electrical transmission line from Utica, NY to New Windsor, NY. The study involves how a newly conceived energy corporation, New York Regional Interconnect (NYRI), is capitalizing upon the U.S. 2005 Energy Act which claims that national energy emergencies exist in regions of the United States that are deemed congested by the Department of Energy. Citizen’s organizations are jointly protesting the proposed power line on the basis that the assertion that their region is currently in an energy “emergency” is fallacious. The grassroots movement speaks to the sociological questions of democratic practice, citizen’s roles in scientific discourse and governmental policy-making, and widely differing claims to knowledge of energy issues. [Article copies available for a fee from The Transformative Studies Institute. E-mail address: journal@transformativestudies.org Website: http://www.transformativestudies.org ©2008 by The Transformative Studies Institute. All rights reserved.]

Uplift Performance of Transmission Tower Foundations Embedded in Clay

The contribution to the uplift stiffness and capacity provided by the clay beneath the base of shallow footings typical in configuration to those employed to support high voltage electricity transmission towers is examined. Pore pressures developed at the base of appropriately scaled footings founded on clay were measured over a wide range of uplift rates in a geotechnical centrifuge. These measurements, coupled with data from tests on identical footings founded on sand, are used to provide insights into the influence of uplift rate on the failure mechanism and footing capacity. Data from a series of undrained triaxial extension tests, conducted over a range of strain rates, are presented and these data combined with finite element back-analyses of the centrifuge uplift tests are used to provide designers with a means of assessing the capacity and load–displacement response of footings on clay subjected to high rates of uplift in service.

Rate effects on the vertical uplift capacity of footings founded in clay

This paper describes results from a series of uplift tests performed in a drum centrifuge on shallow square footings founded on clay and sand, with an overlying sand backfill. The test series investigated footings of various widths loaded at displacement rates extending over five orders of magnitude. Additional tests were performed to examine the influence on uplift capacity of the direction of load inclination. The uplift tests performed on footings founded on sand enabled estimations to be made of the suction that developed at the base of the footings founded on clay. It is shown that the suction mobilised at very fast rates may be assessed using existing undrained bearing capacity approaches and a (rate corrected) operational undrained strength similar to that measured in triaxial extension. The uplift rates required to reach fully undrained conditions are almost two orders of magnitude higher than those for footings loaded in compression, and the upward footing displacements required to generate maximum resistance can be up to 10% of the footing width. These findings have important implications for shallow foundations such as those used to support high-voltage electricity transmission line support structures.

Electric field and voltage sensing at 50 Hz using a thermally poled silica optical fibre

Lab trials of two simple voltage sensor configurations demonstrate the basis of a field deployable voltage sensor capable of measuring the line voltage of a high voltage electricity transmission line. Sensor operation at 50 Hz is demonstrated with sampling rates up to 1000 Hz in the two separate experiments.

An evaluation of the environmental burdens of present and alternative materials used for electricity transmission

This paper describes research using life cycle analysis assessment techniques to determine the environmental impacts associated with the use of present and possible alternative materials utilised in all aspects of high voltage electricity transmission. The study focuses on the National Grid system in England and Wales, where the majority of high voltage electricity is transmitted through steel and aluminium conductors supported above the ground by mild steel lattice type towers. A major aspect of the study is to address the effects of different corrosive environments to which the tower materials are exposed: namely rural, industrial and coastal locations.

Calculation of geomagnetically induced currents (GIC) in a high-voltage electric power transmission system and estimation of effects of overhead shield wires on GIC modelling

Geomagnetically induced currents (GIC) flowing in ground-based technological networks, such as electric power transmission grids, are the ground end of the space weather chain originating from the Sun. GIC constitute a possible source of problems to the system. Matrix formulas enabling the calculation of GIC in a power grid have been presented before. In this paper, we summarise the formulas and also express them in an alternative form that includes the (geo)voltages driving GIC during a space weather event more explicitly. An issue usually ignored in GIC modelling is the effect of overhead shield wires protecting a power grid and generally earthed at the towers. By numerical examples, it is shown in this paper that such neglect causes an insignificant error in comparison with other inaccuracies involved in GIC modelling and is thus really acceptable in practice.

Sulfate Attack on Concrete in an Inland Salt Lake Environment

Several cracks were found on the surface of the concrete foundations that support the steel towers of the Luohe ()-Huaiyang () high-voltage electricity transmission line that is 20 years old and situated in an inland salt lake environment in North China. To analyze the deterioration mechanism that led to this condition, field investigations were carried out and several tests were conducted on the soil and the affected concrete, including XRD (X-ray diffraction), electric probe analysis, and chemical analysis. The results show that the concentration of sulfates is very high (0.39% wt. – 0.67% wt.) in both the surrounding soil and the material around the coarse aggregates inside the concrete. Hence, sulfate attack could be one of the main causes of concrete deterioration. The percentage of sulfates in the surface layer of the concrete was higher than that in the inner layers of the concrete. The sulfates penetrate into the concrete and react with the hydrates of cement to form ettringite (AFt), which leads to increase in the volume and cracking of the concrete.