Mechanical Simulation And Strand Breaks Mechanism Of Jumper Wires Under Strong Wind Loads

Due to its wide area and special geographical location,there are many strong wind areas in Xinjiang.In recent years,750 k V ultra-high voltage（UHV）transmission lines undertaking the task of power transmission from the west to the east in the strong wind areas suffered many strand breaks of jumper wires.This paper selects a typical strand breaks of jumper wires for analysis.The 750 k V high-voltage transmission line located in " the wind area of Dabancheng" suffered five strand breaks of jumper wires in less than 3 years.That is,the strand of the jumper wires will be broken every half a year,which is extremely abnormal and seriously affects the safe operation of 750 k V highvoltage transmission line.According to the statistics of the wind speed in the area where the jumper wires is located,it is found that the strong wind may be a major factor leading to the strand breaks of jumper wires.Therefore,it is of great significance to analyze the mechanical response of the jumper wires under strong wind and explore the mechanism of strand breaks,so as to provide guidance for the implementation of measures to prevent strand breaks.In this paper,the mechanism of strand breaks of jumper wires is explored through the finite element method and related fatigue experiments and tests.The following work has been done:（1）Through comprehensive analysis of the movement form of the jumper wires under the strong wind,the distribution of wind speed,the vibration frequency under the strong wind and the case of strand breaks of conductor in the strong wind area,it is concluded that the vibration of the jumper wires under strong wind is not breeze vibration,subspan oscillation or galloping,but a special vibration with large amplitude and low frequency,and the strong wind is likely to be a major factor causing the strand breaks of the jumper wires.（2）The structure of the jumper wires is not only large,but also spatially distributed.Therefore,establishing a finite element model according to the actual structure to analyze its mechanical response under the strong wind,which is not only difficult to model,but also requires great computational resources.In this paper,a joint simulation method of the whole finite model and the local finite model is proposed,which not only ensures the accuracy of the solution results,but also greatly reduces the amount of calculation.In order to explore whether the jumper wires will have high-frequency resonance under the strong wind,so as to aggravate the failure of the jumper wires,the modeling method is used for modal analysis of the jumper wires.In order to explore the mechanical response of strand breaks of the jumper wires,the modeling method is used for studying the stress distribution of strand breaks of the jumper wires under the different wind levels in detail.The simulation results play an important guiding role in exploring the mechanism of strand breaks of the jumper wires.The subsequent related fatigue experiments and tests verify the accuracy of the modeling method from many aspects.（3）The fatigue experiment of the aluminum steel-reinforced wire（ACSR）under specific level wind is completed on the simulated fatigue experimental platform built in the laboratory,and the fracture morphology and fatigue life of the strand breaks of ACSR are analyzed.（4）The distribution of wind speed,simulation results,fatigue test results,fracture morphology and fatigue life of the strand breaks of ACSR are comprehensively studied,and the mechanism of strand breaks of the jumper wires is put forward.Under the guidance of the mechanism of strand breaks,relevant cooperative units have designed and installed relevant fitting to prevent strand breaks,and achieved preliminary results.