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[en] Public concern over EMF from power lines has resulted in significant opposition to the construction and upgrading of power transmission facilities. Often those opposed to power installations demand that the loads be served with lower voltage and/or underground lines. The problem with this idea is that in typical installations these solutions, while being less aesthetically objectionable, actually increase field levels. This applies to maximum levels and levels at the edge of the right-of-way. This paper will present a common 138 kV double circuit steel pole installation, and contrast the expected field levels against the levels from alternate installations at 138 kV and 34 kV
[en] The approach used by Hydro-Quebec for the environmental assessment of siting power transmission line and towers in northern Quebec is described. Since the first approach was implemented in 1985, an overall revision has been undertaken to take advantage of the lessons learned from recent projects, to develop an approach applicable to various types of projects and environments, and to favor integration of information and consultation with the concerned public. The approach by successive reduction of territory has been retained for determining the optimum siting of facilities. The numerous modifications to the environmental assessment approach have led to the formation of a new approach having the following steps: technical evaluation of the project to determine the characteristics susceptible to be sources of environmental impact; characterizing the environment in which the project is to be located; determining the technical, economic, and environmental performance of the project and identifying a preferred solution; communicating the project evaluation to the public; choosing the final form of the project based on the comments received and establishing the environmental balance; and monitoring the project and its environmental impact after construction. The characteristics of the northern environment having an influence on this evaluation include the presence of environmentally sensitive terrain, reservoirs, work camps, aboriginal lands, and permafrost. 6 figs
[en] Optimization of transmission tower structures is traditionally based on either optimization of members sizes with fixed topographical shape or based on structural analysis modelling strategies without taking cognizance of fabrication and constructability issue facing the contractors . This paper look into an integrated optimum design approach strategies whereby size, shape and topology are combined together with the fabrication issues in the construction of the transmission tower. The topographical algorithm is based on changing the inclination degree of the legs of the tower at first with optimum individual members sizing and later rationalized member sizes are performed through member groupings for the ease fabrication and construction of the transmission tower. The optimum weight using topographical algorithm obtained for the transmission tower is 10,924 kg for singular members and 18,430 kg for element grouping at 10° inclination angle.
[en] The smart grid (SG) system is expected to involve huge amount of data with different levels of priorities to different applications or users. The traditional grid which tend to deploy propriety networks with limited coverage and bandwidth, is not sufficient to support large scale SG network. Cognitive radio (CR) is a promising communication platform for SG network by utilizing potentially all available spectrum resources, subject to interference constraint. In order to develop a reliable communication framework for CR based SG network, thorough investigations on the current radio spectrum are required. This paper presents the spectrum utilization in Malaysia, specifically in the UHF/VHF bands, cellular (GSM 900, GSM 1800 and 3G), WiMAX, ISM and LTE band. The goal is to determine the potential spectrum that can be exploit by the CR users in the SG network. Measurements was conducted for 24 hours to quantify the average spectrum usage and the amount of available bandwidth. The findings in this paper are important to provide insight of actual spectrum utilization prior to developing a reliable communication platform for CR based SG network.
[en] The wind fields around micro-terrain in ultra-high voltage transmission line is analysed by using GWFAP (general wind flow analysis platform). The micro-terrain zone is extracted and selected from ASTER GDEM V2 database, and mixed prism-tetrahedron meshes is generated for the inner zone. Then structured grid sharing the same node height at two zone interfaces is constructed and then converted to unstructured mesh. The B type wind profile with 13m/s different reference wind speed at 10m height is applied to inlet boundary and the wind profile at tower location is obtained. This whole process is automatically carried out and great effort is saved comparing to manual operations. (paper)
[en] In order to study the frequency characteristics of the wireless energy transmission system based on the magnetic coupling resonance, a circuit model based on the magnetic coupling resonant wireless energy transmission system is established. The influence of the load on the frequency characteristics of the wireless power transmission system is analysed. The circuit coupling theory is used to derive the minimum load required to suppress frequency splitting. Simulation and experimental results verify that when the load size is lower than a certain value, the system will appear frequency splitting, increasing the load size can effectively suppress the frequency splitting phenomenon. The power regulation scheme of the wireless charging system based on magnetic coupling resonance is given. This study provides a theoretical basis for load selection and power regulation of wireless power transmission systems. (paper)
[en] It is possible to use designs of overhead high voltage electricity lines which minimise environmental damage. The designs proposed from studies at St. Petersburg Technical University are outlined and the benefits given. (author)
[en] This paper presents a comparative study of current control loop in 3-phase inverter which is used to control the active and reactive output power. Generally, current control loop, power control loop and phase lock-loop are the conventional parameters that can be found in an inverter system controlled by the conventional linear control type, for instance proportional (P), integral (I) and derivative (D). If the grid remains stable throughout the day, PID control can be use. However variation of magnitude, frequency, voltage dips, transient, and other related power quality issues occur in a 3-phase grid often affects the control loop. This paper aims to provide an overall review on the available current control techniques used in grid connected system.
[en] The aim of this paper is to provide a global overview of the technological advances in power transmission, outlining the implications and future policy options for developing countries. There are several ways to improve power transmission technologies, ranging from the introduction of new concepts, such as half-wave, higher phase order, or microwave transmission, to improved applications of old concepts, such as high voltage direct or alternating currents. Some of the improvements come from the need to reduce costs while maintaining overall reliability - others from the need to overcome technological barriers, and might be related to the use of new materials or equipment and/or to a better use of the land and protection of the environment. 1 tab, 25 bibliographies