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Abstractos de publicación

  1. F. Dawalibi, M-A Joyal, J. Liu and Y. Li, "Realistic Integrated Grounding and Electromagnetic Interference Analysis Accounting for GIS, Cables and Transformers During Normal and Fault Conditions", The 5th IEEE PES Asia-Pacific Power and Energy Engineering Conference 2013 (IEEE PES APPEEC 2013), Hong Kong, December 8 - 11, 2013.

    Abstract: A network consisting of a substation including its buried and aboveground components and its overhead transmission lines is analyzed using rigorous electromagnetic fields based analysis. The entire system is modeled and its performance during steady-state normal conditions and fault conditions is examined and discussed. A long section of a buried pipeline is also parallel to the transmission lines. The substation model includes buried and aboveground components such as ground conductors, transformers, cables, Gas Insulated Switchgears (GIS), bus bars and shielding structures in order to account for their impact on the overall network performance during normal and faulted conditions.

  2. F. Grange, S. Journet, S. Fortin and F. Dawalibi, "Transient Analysis of Soil Resistivity Influence on Lightning Generated Magnetic Field", Lightning Protection (XII SIPDA), 2013 International Symposium, October 7-11, 2013.

    Abstract: This paper proposes a full-wave analysis to consider the influence of soil resistivity on the magnetic field inside buildings hit directly by a lightning strike. An electromagnetic theory approach based on the method of moments is used. This method allows for a transient analysis and accounts for the effects of soil resistivity. Calculations are performed in the frequency domain for a simplified case where the lightning channel is modeled assuming a constant current along the channel. The model is selected for ease of comparisons with the examples described in the IEC 62305-4 standard. A time domain numerical analysis is carried out to estimate the influence of soil resistivity on the radiated magnetic field. The effect of the soil resistivity on both the resultant and on the time derivative of the magnetic field is investigated for a 2 m mesh grid-like spatial shield of 10x10x10 m located in horizontally layered soil structures. Examples of transient resultant magnetic field induced by a typical positive stroke on a building represented as a grid like shield are presented, emphasizing the impact of soil resistivity. It is shown that the transient electromagnetic field is moderately affected by soil resistivity changes which, therefore, can be, in some cases, neglected in the computation process.

  3. F. Grange, S. Journet, S. Fortin and F. Dawalibi, "Analysis of Grounding Grids Influence on Lightning Generated Magnetic Field", Electromagnetic Compatibility (EMC EUROPE), 2013 International Symposium. September 2 - 6, 2013, pages 828-832.

    Abstract: This paper proposes a realistic approach to consider the influence of grounding grids on the magnetic field inside buildings due to lightning strikes. An electromagnetic theory approach based on the method of moments is used. This method allows for a transient grounding grid analysis in both the frequency and time domains, and accounts for the effects of the soil. Calculations are performed for a simplified case where the lightning channel is modeled assuming a constant current along the channel. This approach takes radiated fields into account but neglects propagation effects. The model is selected for ease of comparisons with the examples described in the IEC 62305-4 standard. A numerical analysis is carried out to estimate the reduction of lightning-induced magnetic fields inside grid-like spatial shields typically used in reinforced concrete buildings. The influence of grounding grids and soil resistivity on the radiated magnetic field is studied. The performance of various possible grounding grids for the building is compared. Emphasis is given to the effect of the soil resistivity on the results. Major advantages and disadvantages of both analytical and numerical methods are pointed out as well.

  4. Y. Li, F. Dawalibi, H. Zhou and L. Fu, "Analysis of a Large Grounding System and Subsequent Field Test Validation Using the Fall of Potential Method", Asia-Pacific Power and Energy Engineering Conference, APPEEC 2013, Beijing, China, July 12 - 14, 2013.

    Abstract: This paper examines various aspects of the design process and subsequent field test measurements of a large and complex substation grounding system. The study and measurements show that soil layering and lead interference can have a significant impact on the appropriate test location that yields the exact substation ground impedance. Applying a specific percentage rule such as the 61.8% rule for uniform soils to obtain the true ground impedance may lead to unacceptable errors for large grounding systems. This poses significant problems when attempting to validate a design based on raw test data that are interpreted using approximate methods to evaluate substation ground impedance, and determine ground potential rise (GPR), touch and step voltages. Advanced measurement methodologies and modern software packages were used to obtain and effectively analyze fall of potential test data, compute fault current distribution, and evaluate touch and step voltages for this large substation. Fault current distribution between the grounding system and other metallic paths were computed to determine the portion of fault current discharged in the grounding system. The performance of the grounding system, including its GPR and touch and step voltages, has been accurately computed and measured, taking into account the impedance of the steel material used of the ground conductors and circulating currents within the substation grounding system.

 

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