The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform

Carlos Sartori - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of analytic formulations for Surge Impedance calculation of tall transmission towers
    International Journal of Electrical Power & Energy Systems, 2020
    Co-Authors: Eduardo Marques C Costa, Luis F N Lourenco, Carlos Eduardo De Morais Pereira, Marcelo Bender Perotoni, Jose Roberto Cardoso, Carlos Sartori
    Abstract:

    Abstract An analysis of analytic tower models is proposed for simulation of electromagnetic transients in transmission lines supported by towers up to 300 m height. A careful analysis is required for emergent technologies in transmission systems composed of line sections supported by tall towers, with more than 200 m, as recently constructed in the Brazilian Amazon region and across the Yangtze River in China. Usually, conventional towers are modeled using simplistic geometrical forms and analytic formulations. This paper proposes an evaluation of well-established analytic models for representation of transmission towers with more than 50 m height. The analysis is carried out based on reference values of Surge Impedance obtained by using the Finite Element Method – FEM for towers up to 300 m height and then compared to existing analytic models based on the tower representation by cylindrical form. The reference model is developed using a FEM-based multiphysics software, where the tower can be drawn following the original design of its steel structure. The comparison between these two different modeling techniques is presented as a function of the tower height, Surge Impedance calculation and electromagnetic transient simulations in the time domain. From the proposed analysis, the most adequate tower models can be determined for analysis of the lightning performance in power transmission systems composed of tall line sections.

Wang Jianmin - One of the best experts on this subject based on the ideXlab platform.

  • design of multi Surge Impedance model for ultra high transmission tower and analysis onits transient characteristic caused by lightning stroke
    Power system technology, 2007
    Co-Authors: Wang Jianmin
    Abstract:

    Surge response plays a leading role in the transient process caused by lightning stroke to the top of ultra-high transmission tower,so the design of lightning protection for ultra-high transmission tower differs from those for common transmission towers essentially,thus the traditional tower models cannot continue to use in transient characteristic calculation of ultra-high transmission tower as well.In this paper the existing Surge Impedance models for transmission towers home and abroad are introduced in brief,on this basis the authors propose a new improved Surge Impedance model for ultra-high transmission tower.Considering the fact that the Surge Impedances corresponding to different positions of the tower body are not same,the tower body is divided into multi pieces and the Surge Impedance of each piece is calculated respectively.The result of analysis on transient process of ultra-high transmission tower during lightning stroke shows that the new improved Surge Impedance model can tally with actual condition better while lightning stroke occurs.By use of the proposed multi-Surge Impedance model the influences of Surge Impedance,grounding resistance and overhead grounding wire on lightning stroke caused transient characteristic of ultra-high transmission tower are simulated,and simulation results are available for reference to the design of ultra-high transmission tower.

Y Du - One of the best experts on this subject based on the ideXlab platform.

  • Surge behavior on the single conductor with a discontinuity
    2016 33rd International Conference on Lightning Protection (ICLP), 2016
    Co-Authors: Yuxuan Ding, Y Du
    Abstract:

    This paper addressed Surge propagation on a vertical line with a discontinuity. A formula of Surge reflection coefficient expressed by specially-defined Surge Impedance was introduced, which is similar to that of a conventional transmission line. The formula for the discontinuity with a lumped resistance was also presented. With these formulas, Surges on the line with the discontinuity can be evaluated directly. The numerical results for the discontinuity with and without a lumped resistance were presented in this paper. These results were compared with those obtained from a circuit analysis approach - PEEC method. It is found that these results matched well. The average errors are generally less than 1%.

  • transient Surge Impedance of a vertical conductor over the ground
    Asia-Pacific International Conference on Lightning, 2013
    Co-Authors: Y Du, Xinghua Wang, Mingli Chen
    Abstract:

    This paper presents an investigation into transient Surge Impedance of a vertical conductor over the ground during a lightning stroke. An equivalent circuit approach (PEEC) is employed to evaluate path-independent voltage on the conductor. The transient Surge Impedance is then computed in time domain until the reflected Surge is back to the observation point. It is found that transient Surge Impedance increases as time goes on, and is determined by geometry of the conductor and waveform of the injected Surge current. The transient Surge Impedance is neither affected by conductor height nor grounding resistance. The presence of a ground has no effect on transient Surge Impedance. A comparison with the approximate formulas for characteristic Surge Impedance is also made in the paper. The difference varies significantly with conductor height for the Surge current with a long rising time.

  • Numerical investigation of transient Surge Impedance of a vertical conductor over a perfect ground
    2011 7th Asia-Pacific International Conference on Lightning, 2011
    Co-Authors: Y Du, Xinghua Wang, Mingli Chen
    Abstract:

    This paper presents an investigation into transient Surge Impedance of a vertical conductor over a perfect ground during a lightning struck. An equivalent circuit approach is employed, and voltage on the conductor is directly obtained by using traditional circuit analysis techniques. The transient Surge Impedance is then computed with the instantaneous voltage and current obtained in the simulation, which is path-independent. It is found that Surge Impedance generally increases as time goes on, and is determined by the geometry of the conductor and the waveform of the injected Surge current. The simulation shows that the transient Surge Impedance remains the same no matter how long the conductor is. It is affected by conductor diameter, and can be computed by adding an offset if the diameter is changed. The curve of transient Surge Impedance is significantly affected by the waveform of the Surge current. However, it does not change with grounding resistance. The grounding condition does not affect the sure Impedance at the top of the vertical conductor. A comparison with the approximate formulas of characteristic Surge Impedance is also made in the paper. These formulas generally have consistent offsets to the simulation result for the Surge current with a unit step waveform. The difference, however, varies significantly with conductor height for the Surge current with a ramp waveform or a long rising time.

Mingli Chen - One of the best experts on this subject based on the ideXlab platform.

  • transient Surge Impedance of a vertical conductor over the ground
    Asia-Pacific International Conference on Lightning, 2013
    Co-Authors: Y Du, Xinghua Wang, Mingli Chen
    Abstract:

    This paper presents an investigation into transient Surge Impedance of a vertical conductor over the ground during a lightning stroke. An equivalent circuit approach (PEEC) is employed to evaluate path-independent voltage on the conductor. The transient Surge Impedance is then computed in time domain until the reflected Surge is back to the observation point. It is found that transient Surge Impedance increases as time goes on, and is determined by geometry of the conductor and waveform of the injected Surge current. The transient Surge Impedance is neither affected by conductor height nor grounding resistance. The presence of a ground has no effect on transient Surge Impedance. A comparison with the approximate formulas for characteristic Surge Impedance is also made in the paper. The difference varies significantly with conductor height for the Surge current with a long rising time.

  • Numerical investigation of transient Surge Impedance of a vertical conductor over a perfect ground
    2011 7th Asia-Pacific International Conference on Lightning, 2011
    Co-Authors: Y Du, Xinghua Wang, Mingli Chen
    Abstract:

    This paper presents an investigation into transient Surge Impedance of a vertical conductor over a perfect ground during a lightning struck. An equivalent circuit approach is employed, and voltage on the conductor is directly obtained by using traditional circuit analysis techniques. The transient Surge Impedance is then computed with the instantaneous voltage and current obtained in the simulation, which is path-independent. It is found that Surge Impedance generally increases as time goes on, and is determined by the geometry of the conductor and the waveform of the injected Surge current. The simulation shows that the transient Surge Impedance remains the same no matter how long the conductor is. It is affected by conductor diameter, and can be computed by adding an offset if the diameter is changed. The curve of transient Surge Impedance is significantly affected by the waveform of the Surge current. However, it does not change with grounding resistance. The grounding condition does not affect the sure Impedance at the top of the vertical conductor. A comparison with the approximate formulas of characteristic Surge Impedance is also made in the paper. These formulas generally have consistent offsets to the simulation result for the Surge current with a unit step waveform. The difference, however, varies significantly with conductor height for the Surge current with a ramp waveform or a long rising time.

Eduardo Marques C Costa - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of analytic formulations for Surge Impedance calculation of tall transmission towers
    International Journal of Electrical Power & Energy Systems, 2020
    Co-Authors: Eduardo Marques C Costa, Luis F N Lourenco, Carlos Eduardo De Morais Pereira, Marcelo Bender Perotoni, Jose Roberto Cardoso, Carlos Sartori
    Abstract:

    Abstract An analysis of analytic tower models is proposed for simulation of electromagnetic transients in transmission lines supported by towers up to 300 m height. A careful analysis is required for emergent technologies in transmission systems composed of line sections supported by tall towers, with more than 200 m, as recently constructed in the Brazilian Amazon region and across the Yangtze River in China. Usually, conventional towers are modeled using simplistic geometrical forms and analytic formulations. This paper proposes an evaluation of well-established analytic models for representation of transmission towers with more than 50 m height. The analysis is carried out based on reference values of Surge Impedance obtained by using the Finite Element Method – FEM for towers up to 300 m height and then compared to existing analytic models based on the tower representation by cylindrical form. The reference model is developed using a FEM-based multiphysics software, where the tower can be drawn following the original design of its steel structure. The comparison between these two different modeling techniques is presented as a function of the tower height, Surge Impedance calculation and electromagnetic transient simulations in the time domain. From the proposed analysis, the most adequate tower models can be determined for analysis of the lightning performance in power transmission systems composed of tall line sections.