| The research objective of the thesis is focused on the laying technology of large cross-section EHV cables on large bridges. In the paper, various cable laying technologies reported until now are surveyed, and the experience in the 110kV Yangshan Port substation project are discussed, all of which are in use for reference during the research.When laying cables through a large bridge, the strategy to deal with bridge stretching and vibration are crucial. After studying the relationship between the location of the cable and bridge stretching, vibration, the technology such as installation of the offset device and anti-vibration cushion are recommended.The chemical corrosion of the steel, the thermal impact to the reinforced concrete and the interruption of the communication lines are also investigated. Results obtained demonstate that the cable is in safe condition on the bridge. The Donghai bridge project also validates it.The thermal expansion is the main threat to the cable in operation. This thesis provides some proposals: snaky laying could absorb the mechanical deformation, reducing the end thrust; rigid fixation of two ends of the terminal support and connectors are effective in preventing damage caused by displacement; flexible fixation on the top-end of vertical well and two ends of the bridge could absorb the thermo-mechanical deformation and reduce the influence of gravitation.To reduce the metal sheathing induced voltage, this paper offers a varieties of connecting methods. After analyzing and considering the field experience, the Y-shaped grounding with voltage limitation is recommended to apply in shanghai power grid.As mentioned above, the figures cited in the paper are accurate and in line with state standards and other related standards. They are scientific, reliable and reasonable. The conclusions of this object are of much value for designing, operating and decision-making in shanghai power gird. |
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