Study On Mechanical Properties Of 500kV Insulator String Under Wind Rain Coupling In Mountain Pass

Under the condition of micro topography,transmission lines are prone to accidents due to the influence of local extreme climate.Based on the 500kV high voltage transmission line of Xiaohe line in Yunnan Province,this paper studies the V-type composite insulator fracture trip accident.The wind and rain loads and mechanical properties of V-string in mountain pass micro topography are studied.(1)Based on the existing transmission line theory and a large number of relevant literature data,the theoretical simulation method of mountain pass micro terrain wind field and the calculation method of wind load on insulator and conductor are obtained;according to the characteristics of raindrops,the theoretical simulation method of raindrops is obtained,and the calculation method of raindrop impact force is given;(2)Fluent finite element software was used to establish the fluid domain of the micro-terrain model of the full-size pass.The simulated wind field is obtained by setting strict boundary conditions.According to the raindrop simulation method,DPM was introduced into the wind field to successfully simulate the fall of raindrop particles with a diameter of 0～6mm.The motion track of raindrops and the velocity data of transmission line positions were obtained,and the simulation data of wind and rain load under heavy rain,heavy rain and other heavy rain were obtained.(3)According to the simulation data,the wind speed of micro terrain was complex.In this paper,the wire is evenly divided,the wind speed and rain speed of each point on the transmission line are taken to calculate the wind and rain load of each section of the wire.According to the calculation results,it was found that the wind acceleration effect was obvious,and the maximum increment of wind load through the pass was 17.1%.The maximum effect of rain load on wind load is 3.34%in horizontal direction and 4.75%in horizontal and vertical direction.Through comparative analysis,it is found that the stress effect of rain load on V string is less than 5%and can be ignored.(4)Using ANSYS finite element software,the eigenvalue buckling analysis is carried out under the condition of ignoring the influence of fittings and only retaining the mandrel,and the feasibility of simplifying the mandrel is determined.On the basis of this simplification,the improved quadruple and duplex V-series are selected to load the wind and rain load data.It is found that the wind load stress on the windward side of V-string increases by 11.73%and that on the leeward side decreases by 9.59%.With the increase of rainfall intensity,the impact on V-string also increases,with the maximum increase of 5.26%on the windward side and 15.15%on the leeward side.However,it can be ignored to some extent by comparison,and the stress of quadruple V-string is obviously lower than that of double V-string,It can be considered that quadruple V-string is better than double V-string.