随机风作用下耐张串金具的安全性分析

Safety analysis of tension string fittings under random wind

以祁韶线在大风天气下发生LT4联板屈服及屏蔽环断裂为背景,评估耐张串中各金具在极端条件下的安全性。首先基于谐波叠加法模拟多点相关的风速时程曲线,然后分别建立6分裂导线模型和耐张串金具模型,再通过有限元方法模拟单档输电线在随机风作用下的动力响应。将导线的动张力变化最剧烈的区段施加于耐张串金具模型中,数值模拟各金具在该工况下的应力分布,并判断金具的易损位置及破坏机理。研究发现:挂点金具、U型挂环、支撑架局部应力均达到了其屈服强度;LT4联板应力达到了303.9MPa,产生了明显的弯曲现象;屏蔽环的应力振荡频率高,易产生疲劳破坏。同时,针对以上易损金具提出改进措施,为以后优化和改进输电线路金具提供理论参考。

The purpose of this paper is to evaluate the safety of the fittings in the tension string under extreme conditions,based on the background of LT4 connecting plate yielding and shield ring fracture of Qi Shao line in windy weather.Firstly,the multi-point correlation wind speed time-history curve is simulated based on the harmonic superposition method,and then the 6-bundle conductor model and the tension string model are established,respectively.And then the dynamic response of one span transmission line under random wind is simulated by the finite element method.The most violent section of dynamic tension of the conductor is applied to the tension string model to simulate the stress distribution of the fittings under this condition,and to judge the vulnerable positions and failure mechanism of the fittings.It is found that the local stresses of the hanging point fittings,U-shackle and support frame all reach their yield strength,the stress of LT4 connecting plate reaches 303.9 MPa,and obvious bending phenomenon occurs.The stress oscillation frequency of the shielding ring is high,which is easy to cause fatigue failure.The improvement measures for the above vulnerable fittings are put forwarded to provide theoretical reference for future optimization and improvement of transmission line fittings.