ABSTRACT
Power transmission lines are integral and very important components of power systems. Because of the length of these lines and the complexity of the power grids, the lines may encounter various incidents such as lightning strike, shortage, and breakage. When an incident or a fault occurs, a fast process of identification, localization, and isolation of the fault is desired. An accurate fault localization would have a great impact in reducing the restoration time of the system. One of the most popular solutions for fault detection and localization is the distance relays using the impedance-based algorithms. However, these relays are still not perfect with nonzero errors of the fault locations. This paper will present a new approach using the neural networks in addition to a distance relays to correct the fault location estimation of the relay. The solution will be based only on the voltage and current signals measured at the beginning of the lines. The training samples' signals of the transient states on the lines are generated using ATP/EMTP, and then regenerated into the relay tester Omicron CMC-356 to test with the real Siemens 7SA522 relay to improve its fault location results. The numerical results will show that the solution had helped to reduce the average fault location error from 0.92% to 0.42% for 4 types of shortage faults on the lines. [ FROM AUTHOR] Copyright of Turkish Journal of Electrical Engineering & Computer Sciences is the property of Scientific and Technical Research Council of Turkey and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
Lightning is the main source of natural fire, and lightning fire and other types of forest fires together constitute the global forest fire system. It is generally believed that lightning fire, as a natural fire source, has nothing to do with human beings and is different from man-made fire sources, but in fact, human activities have inextricable links with the occurrence of lightning fire. Since 2019, due to the severe impact of COVID-19 lockdowns, non-essential activities and mobility have decreased, which has led to a significant decrease in pollutant concentrations and lightning. In this paper, we linked the lightning fire with modernization process of human beings, the expansion of habitation, the change of underlying surface, the development of prediction technology and firefighting technology, and the laws and regulations of the country, to explore the impact of human activities on the occurrences of lightning and the forest lightning fire. Lightning is the fire source of the three elements in lightning fire occurrence, the lightning that can cause lightning fire is mainly cloud-to-ground lightning. The human activities in recent decades have profoundly affected the content of aerosols in environment. Aerosols are the main factors affecting lightning, and the large amount of pollution aerosols emitted from urban areas, soot aerosols emitted from biomass combustion and urban heat island effect have all increased the probability of lightning occurrence. The average annual ground lightning density of different land cover types is obviously different, and the construction land has the highest average annual ground lightning density. Intense lightning in forest areas has a higher density and slope. Most of the forests are located in high altitude areas, which is consistent with previous studies showing high lightning frequency in high altitude areas. The lightning in forests is intenser, steeper and more destructive, so forest areas are prone to lightning strikes. Lightning has the characteristic of selective discharge, that is, it will discharge into some special areas, which are also known as lightning selection areas, such as the place groundwater is exposed to the ground, where different conductive soils are connected, and where there are underground metal mines, such as copper and iron mines, and underground lake and water reservoir areas. Lightning strikes are caused by changes in soil conductivity caused by human activities such as mining waste rock sites, reservoir construction on mountain tops, and power transmission lines in mountainous areas. At the same time, due to the abundant trees in the mountainous area, it is also important to avoid the resulting lightning fire. With the development of lightning monitoring technology, a lightning location monitoring system has been established in some areas of China. Especially in 2021, the National Forestry and Grassland Administration launched the "Enlisting and Leading" emergency science and technology project of forest lightning fire prevention and control, and the project team has constructed a lightning fire sensing system in the Daxing'anling region with three-dimensional lightning full-wave detection network as the main body, covering the forest area of the Daxing'anling forest region, which can accurately locate the location of cloud-to-ground lightning in real time, improve the monitoring and warning ability of lightning fires, and improve the efficiency of lightning fire discovery. National laws and regulations indirectly affect lightning fires by affecting forest cover and climate change. This paper is expected to provide reference for the occurrence, prevention and control of forest lightning fire in the future, and provide a basis for the formulation of corresponding policies.
ABSTRACT
AFRICAN DEVELOPMENT : Civil engineering works at the 420MW Nachtigal project are over halfway complete, Cameroon's Minister of Water and Energy, Gaston Eloundou Essomba, updated during a recent site visit. The Minister told reporters that the 52% of the civil work has been completed, with 48.2% of first electromechanical lot and 99.8% of the transmission line also complete. The project was initially expected to be complete at the end of 2023, but due to delays caused by the coronavirus pandemic, Nachtigal Hydro Power Company (NHPC) has now been tasked with starting operations of the first machine in July 2023, with final commissioning in July 2024
ABSTRACT
Power infrastructure (electricity towers, mobile phone towers, transmission lines and wires) is a unique anthropogenic structure in terms of material composition, design and continuity serving as artificial habitat to avian wildlife for roosting and nesting. This study aimed at finding out the diversity, abundance and behaviour of birds using the power structures as artificial habitat in the Gujranwala city area, Pakistan. Field data was collected in Feb-Mar 2021 during the COVID-19 pandemic and resulting lockdowns in the city by recording all birds species and nests on power lines along a circular path (~32 km) by dividing into sampling zones. A total of 24 bird species of 16 families were found to be using these structures as roosting and nesting sites. The occupation rate of mobile phone towers is found to be 61%, transmission lines 32%, and electricity towers 1.8%. House crow was the most common species (~20% population) followed by the Black kite (~ 18% population). The spatial distribution pattern of nests on power structures indicated higher concentration in the southwestern area contrary to the highest abundance and diversity in the northwestern area close the urban forest planation. Total 112 nests of 4 species (Black kite, House crow, Common myna and Eurasian collard dove) were present on power lines. Black kite is the most frequent nesting species (>80% of all nests), preferring high structures i.e. transmission lines (99% of all nests) and mobile phone towers (78% of all nests) for making nests. House crow and Common myna make nests on electricity towers at low height. It is found that the area where cutting of trees during the past time period occurred, birds have shifted their nesting habitat from trees to towers (i.e., power structures). Moreover, if habitat destruction continues these power lines will be the new nesting habitat of the birds in the urban area, hence, posing risks to both birds and utility structures. This study also highlighted the importance of strategic plantation in relation to spatial distribution and protection of urban birds.
ABSTRACT
PurposeIn this work, a microstrip antenna array for wireless power transfer (WPT) application is reported. The proposed 4 × 4 antenna array operating at 16 GHz is designed using a flexible Kapton polyimide substrate for a far-field charging unit (FFCU).Design/methodology/approachThe proposed antenna is designed using the transmission line model on a flexible Kapton polyimide substrate. The finite element method (FEM) is used to perform the full-wave electromagnetic analysis of the proposed design.FindingsThe antenna offers −10 dB bandwidth of 240 MHz with beam width and broadside gain found to be 29.4° and 16.38 dB, respectively. Also, a very low cross-polarization level of −34.23 dB is achieved with a radiation efficiency of 36.67%. The array is capable of scanning −15° to +15° in both the elevation and azimuth planes.Originality/valueThe radiation characteristics achieved suggest that the flexible substrate antenna is suitable for wireless charging purposes.