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THERMAL ANALYSIS OF POWER LINES: METHODOLOGIES AND APPLICATIONS
Get PDFThe thermal analysis of cables aims at computing the temperature rise inside the cables due to the heat generated inside the conductor during the normal operation of the cable. The temperature limit of the cable is given by the insulation material: if this limit was exceeded the insulation would be damaged. For this reason it is necessary to calculate the cable ampacity that keeps the cable temperature under the insulation limit. The heat generated by the conductor ows radially from inside to outside (the surrounding medium can be air or earth, in case of buried cable) through all the cable layers. The cable ampacity is calculated solving a circuit that represents the thermal behaviour of the cable. The Standards, in particular the Standard IEC 60287, consider many possible congurations. The Standard IEC 60287 allows to choose the cable (it is possible to specify the dimension and the material of each cable layer) and the layout (cables in air or buried). In case of underground cables, the user can decide how the cables are buried (directly in ground or in conduits), the material surrounding the system and the ambient temperature. The Standard IEC 60287 has some lacks: - it does not consider the presence of external heat sources in addition to the power line cables; - it performs only a steady-state analysis; - it is useful only when a tridimensional analysis is not necessary. In the normal practice, in case of buried cables, it is not unusual that there are external heat sources in addition to the power line cables. And the power line is not always supplied by a costant current; it can be supplied by a load curve and there can be a transient. Moreover in some congurations the 2D section changes along the third dimension, therefore a 2D model is very conservative: a 3D analysis is useful. In all these cases where the Standards are not applicable, another method can be applied. The numerical solver used allows to: - consider any heat sources; - study the transient behaviour; - analize a 3D model. The method has been applied to study a particular part of the power line: the junction zone. In the junction zone the magnetic eld is higher and it can be necessary to shield the power line. The shielding method considered is the High Magnetic Coupling Passive Loop technology. If this system is applied a thermal analysis of the junction zone has to be performed because of the presence of a new set of conductors, in addition to the power line cables. In this case the Standard IEC 60287 is not applicable because: - there are heat sources dierent from the power line cables; - a 3D model is necessary to study the eect of the ending connections of HMCPL and the cable joint
Effects of frequency dependent material properties on the computation of transient eddy currents in human body
No full textEnergy networks in sustainable cities: Polycity project and the case study of Turin – Arquata
Get PDFMagnetic field mitigation of power lines by means of passive loop: technical and economical optimization
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Energy Networks in Sustainable Cities: temperature and energy consumption monitoring in urban area
No full textThe European Commission is supporting many projects intended to improve the use of renewable energy sources and a special attention has been devoted to the case of large-scale urban areas. The Polycity project represents a significant demonstration of this energy policy, which was applied to 3 cities: Barcelona, Stuttgart and Torino. The case of Torino appears of particular relevance because it is dedicated to the improvement of energy performance of existing buildings and installations which is, in our opinion, the most frequent situation.
In particular the most qualifying characteristic of Torino project is the installation of a new combined heat and power generator (CHP), coupled with an absorption chiller, in order to supply energy more efficiently in a district which include the Housing Authority of the Province of Torino (ATC) building and 30 council buildings. The trigeneration is able to supply electricity and cooling power to the main office building and, thanks to the coupling to the existing district heating system, it provides thermal energy for space heating and hot water to the council buildings in the district.
The paper presents the analysis activities performed during Polycity project to understand the role of monitoring and control in a complex energy system with the aim of improving the efficiency and reducing the energy consumption. Further analysis in terms of economical and environmental benefits have been already described in another paper where an optimal management system was used to improve the efficiency of the plant. Here only the results analysis of the project monitoring are analysed. Particular attention has been dedicated to the analysis of temperature profiles measured in some flats of residential buildings: these data have been collected for more than one year. Possible relationships between energy consumption and temperature management have been analysed and discussed in order to improve the results
Energy Saving in Social Housing: an Innovative ICT Service for Occupant Behaviour
No full textThe European Commission is supporting many projects in the field of energy saving, with the aim to improve inhabitants behavior and to help Europe to meet emission targets. The objective of the Balanced European Conservation Approach - ICT services for resource saving in social housing (BECA) Project is to enable consumption reduction of key resources in European Social Housing by providing usable ICT-based services for Resource Management and Resource Use Awareness, directly by tenants. The project is developing a range of ICT innovative services to be provided to the inhabitants of 7 different European cities: Örebro (Sweden), Manresa (Spain), Darmstadt (Germany), Torino (Italy), Havirov (Czech Republic), Ruse (Bulgaria), and Belgrade (Serbia). The ICT service will deliver to tenants information with direct timely and comprehensible feedback on the impact of their behavior on a full range of resource uses, thereby enabling tenants to save energy and water. This paper describes the project highlighting the adoption of ICT service in Torino and the initial results
Magnetic field mitigation by means of passive loop: technical optimization
No full textPurpose - The purpose of this paper is to present an approach to design passive loop systems in order to reach good performances. Design/methodology/ approach - The optimization has been performed by means of the MATLAB optimization toolbox "Gatool" which solves the optimization problems with a genetic algorithm. Findings - Several configurations have been analyzed by varying the number of loops from 2 to 15, whose geometry has been chosen by the genetic algorithm. Considering a five loops configuration, along the reference path it is possible to obtain a shielding factor almost constant and equal to 3.5. Originality/value - The optimized configurations have been compared with a practical employed layout composed of 17 closed loops placed above and around the junction zone. The shielding factors obtained by the six loops configuration are comparable with the ones of the practical layout
The high magnetic coupling passive loop: A steady-state and transient analysis of the thermal behavior
No full textThis paper deals with a new concept of technology for the mitigation of the magnetic field produced by underground power lines called "High Magnetic Coupling Passive Loop" (HMCPL). The working principle of this technique is the creation of a current with the same amplitude but opposite phase for each source conductor, in order to nullify the magnetic field in a specified region. Since the number of thermal sources in the shielding region is roughy doubled, the aim of the paper is the investigation of the thermal behavior of HMCPL directly buried in the ground, both in transient and in steady-state conditions. The study is carried out with simulations in order to verify any possible configurations of the shield. Results confirm that HMCPL is a safe technology which does not modify the thermal behavior of the power lin
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