High-voltage Electric Power Transmission Research Articles

Effect of high-voltage power lines electromagnetic field on growth and development of green bean (Phaseolus vulgaris L.)

Relevance. High voltage electric power transmission lines (HVEPTL) cover a fairly large area of agricultural land all over the world. Investigations of electromagnetic field effect on growth and development of plants are held in various countries. The reaction of individual plant species and even varieties to the electromagnetic field manifests itself in different ways. The network of HVEPTL is growing steadily in our region as well. Nevertheless, information about the effect of the electromagnetic field on bean plants is rather scares. The aim of the present work was to evaluate HVEPTL effect on the growth and development of vegetable beans, depending on the intensity of the electromagnetic field.Material and Methods. The work was achieved on green beans Phaseolus vulgaris L. (Sakfit, Pagoda, MBZ 556, Arishka cvs) grown in conditions of different electromagnetic field values under HVEPTL. Biometrical parameters, plant productivity, yield, dry matter, photosynthetic pigments content, ascorbic acid, total antioxidant activity and total phenolics were determined.Results. In the ranges of electric field values from (5-10) to (400-440) B/m and magnetic field from 0 to 0.53 μT a beneficial effect of electromagnetic field on accumulation of leaves photosynthetic pigments (15-65% increase of chlorophyll а and 6-52% increase of chlorophyll b), polyphenol content (increase up to 17%), antioxidant activity (1-15% increase), and dry matter content (2,5-11% increase) and beans ascorbic acid levels (12-28% increase) were registered. Accordingy, increased plants growth, development and productivity were demonstrated. Peculiarities of beans plants grown under HVEPTL included decrease leaves carotene levels at electric field level of 60-100 B/m (70 m form HVEPTL), and lack of correlation between chlorophyll and carotene in leaves and total antioxidant activity and phenolics content at the stage of technical ripening.

Analyzing the Limit Loading of Transmission Tower by Means of Finite Element Model

The truss structure has been widely used in the area of high-voltage electric power transmission due to its limited mass and great stiffness. The carrying capacity should be known in advance before the practical usage of transmission tower. As a result, analyzing the limit loading of transmission tower can be significantly useful. In this research, a model of transmission tower structure has been established by a software named Abaqus 6.14. By imposing different loading forces to the finite element model, the locations of limit stress and displacement were figured out. It has shown that the truss structure in this article can bear no more than 198 kN of loading. Stresses meanly distribute in the two side of the tower body, decreasing with the increasing height. The limit stress shows up at the bottom and is at same side of loading force. Stress and displacement responses fit Hooke’s law perfectly, in other words, the proposed finite element model can be used in the design of transmission tower in practice.

Dielectric characterization of vegetable oils during a heating cycle.

The knowledge of the dielectric properties of oils is of great importance for several industrial applications, such as microwave-assisted oil frying for foods and high voltage electric power transmission. In this paper, we present the complex permittivity of vegetable oils (canola, olive, soybean, coconut) at 2.50GHz using the cavity perturbation technique from 28 to 200°C (temperature close to the smoking point of oils). The measurements were taken with a cylindrical cavity operating at the TE111 mode with an unloaded Q of 4950. In addition, free fatty acids, peroxide index and color were measured before and after heating.

Childhood leukaemia and distance from power lines in California: a population-based case-control study.

Background:Studies have reported an increased risk of childhood leukaemia associated with living near high-voltage electric power transmission lines that extend to distances at which magnetic fields from lines are negligible. We conducted a large records-based case-control study of childhood leukaemia risk in the population living near power lines in California.Methods:The study included 5788 childhood leukaemia and 3308 central nervous system (CNS) cancer cases (for comparison) born in and diagnosed in California (1986–2008), and matched to population-based controls by age and sex. We geocoded birth address and estimated the distance from residence to transmission lines using geographic information systems, aerial imagery, and, for some residences, site visits.Results:For leukaemia, there was a slight excess of cases within 50 m of a transmission line over 200 kV (odds ratio 1.4, 95% confidence interval 0.7–2.7). There was no evidence of increased risk for distances beyond 50 m, for lower-voltage lines, or for CNS cancers.Conclusions:Our findings did not clearly support an increased childhood leukaemia risk associated with close proximity (<50 m) to higher voltage lines, but could be consistent with a small increased risk. Reports of increased risk for distances beyond 50 m were not replicated.

Investigations on the Seismic Responses of Structures with a Suspended Mass

This paper presents the shaking table tests and an analytical study of structures with a suspended mass under coupled horizontal and tilting ground motions (CHT) caused by an earthquake. Shaking table tests of a 1:10 scaled model for a converter valve hall with a suspended mass in a high-voltage direct current electric power transmission station are carried out. The equations of motion for the structure, including the influence of the rotary inertia of the suspended mass, are derived. The responses of the model to different ground motions during an earthquake are investigated. It is found that the tilting ground motion plays a significant role in predicting the seismic response of the structure, and it needs to be considered in association with the horizontal ground motion. The response of the structure with a suspended mass to CHT ground motion is much larger than that to horizontal ground motion. The possibility of replacing the steel cables with springs as the suspending components is also investigated, and the spring is shown not to influence the acceleration and displacement responses greatly, but it significantly reduces the tension in the suspending components. Therefore, when a suspended mass is used as a mass-pendulum mitigation system, it is more advantageous to use springs or members having a low axial rigidity as the suspending components. In addition, the effects of the length of the cables and springs on the seismic response of the model with a suspended mass are also explored. It is found that the shorter the cables (or springs), the better the mitigation effects of the suspended mass on the main structure.

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.

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.

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.

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.

125: Reverse Environmental Justice: The Case of High Voltage Electric Power Transmission Lines

125: Reverse Environmental Justice: The Case of High Voltage Electric Power Transmission Lines

Management of the geomagnetically induced current risks on the national grid company's electric power transmission system

The National Grid Company plc (NGC) is the owner and operator of one of the world's largest privatised high-voltage electric power transmission systems in England and Wales at 400 and 275 kV . As owner operator it is responsible for the secure and reliable delivery of electrical energy to all the 25 million electricity supply customers in England and Wales. The transmission and distribution systems in UK have experienced significant effects during past geomagnetic storm events especially during solar cycles 21 and 22. These effects included generator reactive power output swings, voltage dips, negative sequence alarms and transformer failures. Geomagnetically induced current (GIC) monitoring was installed in 1989 and operational procedures were put in place based on global solar weather forecasts. These measures were not capable of delivering reliable information and thus gave many false operational alarms. Their only real use was for post event forensic purposes. Since the cycle 22 solar peak activity the UK transmission system has developed to become more meshed, heavily loaded and dependent on the availability of reactive compensation equipment for voltage control. NGC carried out GIC impact risk assessment in 1998. This reviewed available options for managing this risk including investigation of blocking measures, a reliable local GIC forecast, GIC monitoring, a review of transmission equipment capabilities to withstand GIC conditions and operational procedures to manage the risk. As a result of the risk assessment NGC completed installation of a Metatech Spacecast/Powercast space weather forecasting system in May 1999. EPRI Sunburst 2000 based transformer monitoring systems were fully integrated in January 2000 in time for peak solar storm activity in solar cycle 23. This paper will describe the risk analysis undertaken, the risk management processes put in place and the performance of the forecasting and monitoring systems, respectively.

Transmission Worth of Photovoltaic Generation

Long distance, high-voltage electric power transmission to transfer electricity produced by solar photovoltaic (PV) systems has received little, if any, attention within the U.S. utility solar power community. In fact, current thinking among utility solar power researchers and planners has shifted from visions of centralized power stations to one of distributed, smaller generation systems. This shift of interest from centralized to distributed photovoltaic power generation, however, appears to be based in part on an unstated premise of limited land area for PV power plants within a utility's service area. Hydroelectric power planners have clearly taken a different approach. Given the limited number of good sites for large scale hydropower generation and the adverse land-use relationship between densely populated, electric power demand centers and the construction of hydroelectric facilities, long high-voltage transmission lines are typically required. In this paper an order of magnitude analysis is made of the economic feasibility of using transmission lines to transport solar photovoltaic power from sunny to cloudy regions.