Aerial Lines Research Articles

Effect of high-resistivity ground on the lightning performance of overhead lines

This paper presents an approximate formula for the peak-value of the lightning overvoltages induced on aerial lines installed over high resistivity ground, which is valid up to 10 kΩ m. The formula is validated by comparing its results with results obtained from more accurate techniques. The formula is then applied in a Monte Carlo code to assess the effect of high-resistivity ground on the lightning performance of distribution lines without grounded neutral conductor. The results show that, for good conducting ground (e.g., 100 Ω m), indirect flashes are relevant for the 100 kV CFO lines, but they are not relevant for the 170 kV CFO lines. For poorly-conducting ground (e.g., 1000 Ω m), indirect flashes are relevant for 170 kV CFO lines, but they are not relevant for the 300 kV CFO lines. Indirect flashes become relevant for the 300 kV CFO lines only for very poor-conducting ground (e.g., above 2000 Ω m). The paper results also show that using a grounded neutral conductor improves significantly the indirect lightning performance of distribution lines.

Unmanned Aerial Patrol Technology Based on Tracking Algorithm of Target Tracking

In order to study the power patrol technology of unmanned aerial vehicle, the tracking algorithm was applied. The automatic patrolling of power lines was discussed in terms of algorithms. An unmanned aerial vehicle transmission line inspection method based on machine vision was proposed. The image and video of the unmanned aerial vehicle inspection of the power line had a complex background. By Wiener filtering de-noising and probability density functions, the image clarity was improved. According to the existing tracking techniques and algorithms, a Camshaft target tracking algorithm based on lossless Kalman filter was proposed. The method of non-destructive Kalman filter was adopted to predict the region of interest of power line identification. Using the Camshaft algorithm, the prediction of the window was searched and the size of the window was adjusted. Transmission lines were tracked in real time. The results showed that the restoration effect of the algorithm was obvious. The clarity of the image was improved. It prepared for the extraction and tracking of the future transmission lines. Therefore, the proposed method provides a feasible way for the UAV power line inspection technology based on machine vision.

Abundance of Whales in West and East Greenland in Summer 2015

An aerial line transect survey of whales in West and East Greenland was conducted in August-September 2015. The survey covered the area between the coast of West Greenland and offshore (up to 100 km) to the shelf break and in East Greenland from the coast up to 50 km offshore crossing the shelf break. A total of 423 sightings of 12 cetacean species were obtained and abundance estimates were developed for common minke whale, (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), harbour porpoise (Phocoena phocoena), long-finned pilot whale, (Globicephala melas) and white-beaked dolphin (Lagenorhynchus albirostri). The estimates were corrected for perception bias and availability bias where possible. Data on surface corrections for minke whales and harbour porpoises were collected from whales instrumented with satellite-linked time-depth-recorders. Options for estimation methods are presented and the preferred estimates are: minke whales: 5,095 (95% CI: 2,171-11,961) in West Greenland and 2,762 (95% CI: 1,160-6,574) in East Greenland, fin whales: 2,215 (95% CI: 1,017-4,823) in West Greenland and 6,440 (95% CI: 3,901-10,632) in East Greenland, humpback whales: 993 (95% CI: 434-2,272) in West Greenland and 4,223 (95% CI: 1,845-9,666) in East Greenland, harbour porpoises: 83,321 (95% CI: 43,377-160,047) in West Greenland and 1,642 (95% CI: 319-8,464) in East Greenland, pilot whales: 9,190 (95% CI: 3,635-23,234) in West Greenland and 258 (95% CI: 50-1,354) in East Greenland, white-beaked dolphins 15,261 (95% CI: 7,048-33,046) in West Greenland and 11,889 (95% CI: 4,710-30,008) in East Greenland. The abundance of cetaceans in coastal areas of East Greenland has not been estimated before, but the limited historical information indicates that the achieved abundance estimates were remarkably high. Comparing the estimates from 2015 in West Greenland with a similar survey conducted in 2007, there is a trend towards lower densities in 2015 for the baleen whale species and white-beaked dolphins. Harbour porpoises and pilot whales, however, did not show a similar decline. The decline in baleen whale and white-beaked dolphin abundance is likely due to emigration to the East Greenland shelf areas where recent climate driven changes in pelagic productivity may have accelerated favourable conditions for these species.

Some Physical and Computational Features of Unloaded Power Transmission Lines' Switching-off Process

The paper presents results of research some physical and computational features of unloaded power transmission lines switching-offs. It was stated that there are not monotonous dependence between magnitudes of transitional voltages at switching-off high voltage aerial lines and their lengths. There was studied influence of the circuit-breaker type (SF6 or vacuum ones) on transitional voltages. Features of use the ordinary differential equations' solvers at computer simulation from the point of view stability of solutions and simulation time consuming were investigated in the presented research.

New insights on the morphology and taxonomy of the gecko Mediodactylus ilamensis (Reptilia: Gekkonidae)

As a recently described species, Mediodactylus ilamensis is one of the least studied species of endemic reptiles of Iran. In this study a total number of 11 specimens of Mediodactylus ilamensis were collected from type locality (Zarin-Abad) as well as a new locality in Dinar-Kooh Preserved area, Abdanan Township approximately 27 km on an aerial line in the east of type locality. To investigate morphological variation and reveal sexual dimorphism we employed 32 metric and meristic characters. The most important morphological characteristics of this species are as follow: all scales of the body, with the exception of intermaxillaries, nasals, chin shields, and upper and lower labials, strongly keeled; postmentals absent, dorsal crossbars broad and equal to, or wider than, interspaces; scales of frontal and supraocular regions toward snout are multi-keeled (in some scales up to six keels) and polyhedral. Of the studied morphological characters only two are different significantly between males and females: number of active precloacal pores and ear diameter (vertical). Based on the new material, the validity of M. ilamensis as a full species, well distinguishable from other species of Mediodactylus, is confirmed. Observations on taxonomy, ecology and behavior are given.

基于灾害预防的配电网架空线图像监测系统设计

基于灾害预防的配电网架空线图像监测系统设计

Occurrence, distribution and abundance of cetaceans off the western Eyre Peninsula in the Great Australian Bight

This study provides the first assessment of the occurrence, distribution and abundance of cetaceans in shelf and coastal waters off the western Eyre Peninsula, eastern Great Australian Bight, South Australia. We undertook aerial line transect surveys to estimate the abundance of common dolphins, and to assess the occurrence and distribution of other small and large cetaceans. Two along shore surveys were also flown to assess occurrence of endangered southern right whales in coastal waters. Five cetacean species were detected: seven southern right whales, three humpback whales, one minke whale (unknown species), 71 schools of common dolphins, and 14 schools of bottlenose dolphins. Abundance of common dolphins was estimated to be 20,000–22,000 using distance sampling methods with densities of 0.67–0.73 dolphin/km2. Comparisons of common dolphin densities off the Eyre Peninsula in the eastern GAB with other regions around the world show that shelf waters off the Eyre Peninsula represent an important habitat for common dolphins.

Agent-based tool to reduce the maintenance cost of energy distribution networks

There has been continuous research in the energy distribution sector because of its huge impact on modern societies. Nonetheless, aerial high voltage power lines are still supported by old transmission towers which involve some serious risks. Those risks may be avoided with periodic and expensive reviews. The main objective of this work is to reduce the number of these periodic reviews so that the maintenance cost of power lines is also reduced. More specifically, the work is focused on reducing the number of periodic reviews of transmission towers to avoid step and touch potentials, which are very dangerous for humans. A virtual organization-based multi-agent system is proposed in conjunction with different artificial intelligence methods and algorithms. The developed system is able to propose a sample of transmission towers from a selected set to be reviewed. The system ensures that the whole set will have similar values without needing to review all the transmission towers. As a result of this work, a website application is provided to manage all the review processes and all the transmission towers of Spain. It allows the companies that review the transmission towers to initiate a new review process for a whole line or area, while the system indicates the transmission towers to review. The system is also able to recommend the best place to locate a new transmission tower or the best type of structure to use when a new transmission tower must be used.

Effect of duration of the pause single-phase auto-reclosing on electro-power transmission capacitance

This paper discusses the problem associated with accidents in the aerial line (AL) ultra-high voltage (UHV) due to its big length. In lines with a voltage of 500-1150 kV the overwhelming proportion of trips (98%) is caused by single-phase short circuit (SPSC). A substantial portion (70%) single-phase short circuits is erratic arc accidents which can be successfully eliminated in a high-speed auto-reclosing (HSAR) or single-phase auto-reclosing (SPAR). Success single-phase auto-reclosing (SPAR) at liquidation by single-phase short circuit (SPSC), on the one hand, is determined by the characteristics of the secondary arc current, and on the other hand the effectiveness of ways to reduce secondary arc current and recovery voltage development. The minimum dead time, at a HSAR it is usually taken as 0.5 s., at single-phase autoreclosing (SPAR) it depends on the current value of the arc support is in the range of 0.5-3.0 s. The article shows high efficiency of use single-phase auto reclosing (SPAR) at liquidation SPSC in a single-chain AL voltage of 500 kV, the dependence of the bandwidth of transmission in maintaining the dynamic stability from the length of the pause SPAR.

Modelación y Validación en ATP de los Cables Subterráneo y Submarino del Sistema de Subtransmisión Baltra - Santa Cruz

En este trabajo, basados en el estado del arte, se presentan los criterios usados para la modelación y validación de los cables tripolares subterráneo y submarino del sistema de subtransmisión Baltra– Santa Cruz. Para modelar los cables en rutinas Cable Parameters incluida en programas del tipo EMTP, se realizó un tratamiento previo de los datos de diseño y constructivos de los cables; además, para analizar el cable tripolar subterráneo fue necesario agregar a su modelo una armadura ficticia de tal manera que se pueda modelar como un cable tipo “tubo” (Pipe).
 El estudio de transitorios electromagnéticos de energización de la línea se realizó usando el software ATP, pero debido a que el estado del arte indica limitaciones en el modelo de cables y líneas aéreas no simétricas cuando se usa Bergeron o JMarti, incorporados en ATP, se realizó un análisis que permitió determinar hasta qué punto es válido el modelo JMarti mediante una comparación de sus respuestas transitorias de voltaje con las ofrecidas por el modelo WideBand, incorporado en EMTPRV el cual es considerado el modelo más preciso de líneas y cables en la actualidad. Para este propósito los modelos JMarti de cable submarino y subterráneo fueron ajustados con un valor de frecuencia de acuerdo a lo sugerido por CIGRÉ.
 Los resultados indican que el modelo JMarti ofrece señales de voltaje aceptables únicamente para el conductor energizado, mientras que para voltajes inducidos en otros conductores de fase y pantallas y armaduras metálicas el modelo falla.

Assessing the number of moored fishing aggregating devices through aerial surveys: A case study from Guadeloupe

Moored fish aggregating devices (MFADs) are increasingly being used in small-scale tropical fisheries to access pelagic fish species that are otherwise difficult to harvest in large numbers. Little attention has yet been paid to monitoring MFADs in coastal areas, however. This is most likely due to the small-scale nature of most fisheries that utilize them and the presumed lower impact of those fisheries on fish stocks and their ecosystems. In this paper, we examined the abundance and density of MFADs around Guadeloupe, using aerial line transect surveys. Estimated MFAD densities were found to be high compared with previously reported densities in this area, especially within the 22–45km range offshore. We examine and discuss possible reasons for these high densities. The main drivers appear to be the target species dolphinfish (Coryphaena hippurus) and yellowfin tuna (Thunnus albacares) and related fishing behaviour. We present different approaches for reducing and monitoring MFADs densities, including the co-management of MFAD territorial use rights by fishing communities.

Changes in numbers and distribution of wintering Long-tailed Ducks Clangula hyemalis in Swedish waters during the last fifty years

The Long-tailed Duck Clangula hyemalis is the most common wintering waterfowl in Swedish marine waters but it is not well covered in the International Midwinter Counts due to its offshore distribution making special surveys necessary for the species. Surveys covering the entire Baltic Sea were organized for the first time in 1992/1993 with follow-up surveys in 2007–2011 and 2016. In Sweden, aerial line transect surveys covered all areas of importance for the Long-tailed Duck during the last two all-Baltic surveys. In the 1970s extensive regional surveys were done from coastguard boats and airplane. The total wintering population of Long-tailed Duck was estimated to be around 370,000 individuals in 2016 compared to 436,000 in 2009, and in the order of 1,400,000 in 1992/1993, indicating an ongoing decrease. Comparing the more recent surveys with the surveys from the 1970s, the most marked changes in wintering numbers were found east of Gotland, where only a small proportion of the numbers estimated in the 1970s remained. Decreases were also found in the waters around Öland, whereas no marked changes were noted for the smaller wintering populations of the east coast archipelagos.

가공 배전선의 전자유도전압에 대하여 대지 귀로전류 원리를 반영한 중성선 차폐계수 계산 방법

가공 배전선의 전자유도전압에 대하여 대지 귀로전류 원리를 반영한 중성선 차폐계수 계산 방법

Способы ликвидации однофазных коротких замыканий в воздушных линиях сверхвысокого напряжения

Способы ликвидации однофазных коротких замыканий в воздушных линиях сверхвысокого напряжения

Aerial line model for power system electromagnetic transients simulation

In this study, a new model for aerial multiconductor transmission lines with frequency dependent electrical parameters is presented. The new model is called here A-line model and is a two-port model based on the method of characteristics and finite differences that does not require segmenting the transmission line. The frequency dependence of electrical parameters due to field penetration in conductors and Earth is taken into account by means of the penetration impedance or skin impedance. Moreover, in the proposed model there is no need of splitting in propagation modes; therefore, the numerical implementation is very simple. With the purpose of validation, results from the numerical Laplace transform and universal line model are employed. From the results, it is found that the A-line model is accurate and robust with an execution speed that makes it a strong candidate for real-time simulations.

Nesting Pair Density and Abundance of Ferruginous Hawks (Buteo regalis) and Golden Eagles (Aquila chrysaetos) from Aerial Surveys in Wyoming

Abstract Raptors that inhabit sagebrush steppe and grassland ecosystems in the western United States may be threatened by continued loss and modification of their habitat due to energy development, conversion to agriculture, and human encroachment. Actions to protect these species are hampered by a lack of reliable data on such basic information as population size and density. We estimated density and abundance of nesting pairs of Ferruginous Hawks (Buteo regalis) and Golden Eagles (Aquila chrysaetos) in sagebrush steppe and grassland regions of Wyoming, based on aerial line transect surveys of randomly selected townships. In 2010 and 2011, we surveyed 99 townships and located 62 occupied Ferruginous Hawk nests and 36 occupied Golden Eagle nests. We used distance sampling to estimate a nesting pair density of 94.7 km2 per pair (95% CI: 69.9–139.8 km2) for Ferruginous Hawks, and 165.9 km2 per pair (95% CI: 126.8–230.8 km2) for Golden Eagles. Our estimates were similar to or lower than those from other stud...

Indirect Lightning Performance of Aerial Distribution Lines Considering the Induced-Voltage Waveform

This paper shows that the wave-shape parameters of lightning-induced voltages (front-time and time-to-half value) are influenced by the ground resistivity, the line length, and the distance between the flash and the line. In general, these parameters increase with the ground resistivity, the line length, and the distance from the flash. The probabilistic distribution of the waveshape parameters are presented, considering different values of line length and ground resistivity. The effect of the induced voltage waveform on the indirect lightning performance of aerial distribution lines is evaluated using the disruptive effect (DE) method as a flashover criterion. The resulting flashover rates differ significantly from those obtained when only the peak value is used as flashover criterion. The use of a correction factor to multiply the line critical flashover when using the peak value as a flashover criterion is investigated.

Russian

Russian

Monitoring abundance of golden eagles in the western United States

ABSTRACTUnder the Bald and Golden Eagle Protection Act, the United States Fish and Wildlife Service (Service) can authorize take of golden eagles (Aquila chrysaetos), such as nest removal, disturbance, and lethal take, if the take is compatible with the preservation of the golden eagle. The Service needs baseline information on the current abundance and trend of subpopulations of the golden eagle to properly manage take of the species. Annually during late summer of 2006–2012, we used distance sampling on approximately 17,500 km of aerial line transects to estimate golden eagle abundance in 4 Bird Conservation Regions (BCRs; North American Bird Conservation Initiative Monitoring Subcommitte 2007) that collectively cover about 80% of the species' range in the coterminous western United States. We estimated study area abundances of 24,509 (90% CI: 19,406–31,947) in 2006 and 21,715 (90% CI: 18,165–27,624) in 2012, including all breeding and non‐breeding individuals. We used a Bayesian hierarchical model to estimate trends in individual BCRs and the entire study area based on numbers of golden eagles counted along surveyed transects. We detected declines (90% credible intervals [CRIs] for trend coefficients <0.0) in numbers of golden eagles classified as juveniles in BCR 10 (Northern Rockies) and BCR 16 (Southern Rockies and Colorado Plateau) during 2006–2012. However, our results indicate the total abundance of golden eagles has not declined 2006–2012 in much of the western United States. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Aerial Transmission Lines Image Restoration Technology Research Based on the Improved Maximum Entropy

According to the limitations of the shooting environment, captured image exist the phenomenon of image blurring and noise. This paper proposes that the improved maximum entropy method recovery blurred image which acquire in aerial. Finally, according to the first order Markoff theory to evaluate the quality of the processed image, the results show that maximum entropy image restoration method compared to the conventional approach increase image clarity and details more better.