Research On Design Method Of Independent Tapered Steel Tube Lightning Rod Structure In Substation

Lightning rod prevents the power distribution devices in substations from being damaged by lightning.According to GB50135-2006,in the area with seismic fortification intensity of 6th degree,the cross-section aseismic calculation of structural members can be omitted.Wind load is the control load of lightning rods.Compared with the traditional cylindrical independent steel tube lightning rod,the mechanical performance of the independent tapered steel tube is better.Besides the traditional material mechanics method,the current design methods of lightning rods mainly include random vibration model design method based on time-history simulation of fluctuating wind speed and quasi-static wind load design method based on finite element software modeling.Time-history simulation is too time-consuming and the copyright cost of finite element software is expensive.Neither has been widely used by designers.Based on the problems,the following research was carried out in this paper:(1)Compared the reliability of independent steel tube lightning rod designed with the wind-induced vibration coefficient in the Design Manual of Substation Gantry with that with the one from AR simulation.Based on an example of lightning rod replacement project in a 220 kV substation in the area with seismic fortification intensity of 6 degree,the material mechanics calculation method of a 35 m steel tube lightning rod according to the Manual and relevant norms was showed,including strength checking of steel tube and horizontal displacement calculation of 30 m elevation of lightning rod.Based on the assembly diagram of the lightning rod,the finite element model was established in ANSYS Workbench.Moreover,the wind-induced vibration coefficients in the Manual and from AR simulation were substituted to calculate the horizontal displacement of the structure respectively,and their value was compared.(2)P-Δ Effect increase factor of independent steel tube lightning rod was studied.Based on the original design scheme of the 220 kV substation,the optimal design was carried out,and the ANSYS finite element models of 25 m,35m,45 m,55m and 60 m independent steel tube lightning rod were established.The top horizontal displacement of the support was calculated when the basic wind pressure is between 0.2 and 1.2,considering the P-Δ Effect and not.The value of the P-Δ Effect increase factor was summarized.(3)The relationship between the slope and top horizontal displacement of the steel tube was studied.According to the different wall thickness and slope,4*28 ANSYS finite element models of the tapered steel tube with 10 m height and 450 mm bottom outer diameter,and 7*53 ones with 10 m height and 1200 mm bottom outer diameter were established.The relationship curve between the slope and the horizontal displacement of the top of the steel tube was drawn through the finite element calculation data,and the conclusion was drawn that the horizontal displacement of the top of the tapered steel tube tended to decrease with the increase of the slope.Based on the research above,there is a conclusion put forward about a simplified method for the structural design of independent tapered steel tube lightning rod,which will facilitate designers,improve design efficiency and facilitate the popularization and use of the independent tapered steel tube lightning rod.