局部瞬时激励下架空导线微风振动波的传播演化

Propagation evolution of aeolian vibration waves in an overhead conductorunder local instantaneous excitation

微风振动是架空导线疲劳断股、断线的重要原因。为分析局部锁定后导线的微风振动过程,将架空导线简化为张力主导的无限长连续弦模型,考虑局部锁定的随机性和瞬时性,将导线在任意时刻任意位置形成的局部锁定简化为瞬时脉冲激励,采用积分变换法获得了系统在时间和空间上的双格林函数解,分析了脉冲波在弦模型中的传播过程和固定约束边界的反射规律。进而采用局部脉冲激励法对导线内行波的传播演化特性进行试验研究,采用高清摄像机对振动波进行捕捉,基于自编程序进行视频图像处理及分析。结果表明:自编程序能够提取标记测点的瞬时位移,脉冲波在传播过程中波速恒定、波面轮廓能够保持较好的形态不变形。局部瞬时激励形成的脉冲波沿导线向两侧档端传播,在经过档端约束后形成反射波沿导线传播,两侧形成的反射波相遇后相互叠加引起导线持续振动。试验现象与理论分析一致。

Aeolian vibration is an important cause of fatigue strand breaking and line breaking of an overhead conductor.It is of great theoretical and practical value to study the propagation evolution of aeolian vibration wave of a long span conductor.The overhead conductor was simplified into a continuous string model dominated by tension.Considering the randomicity and instantaneity of local lock-in,the local lock-in formed by the conductor at any time and at any position was simplified into instantaneous pulse excitation.The double green function solution of the system was obtained by using the Fourier transform and the Laplace transform,and the propagation and reflection laws of pulse wave were analyzed.Furthermore,the local instantaneous excitation method was used to test the propagation evolution characteristics of the internal wave in the wire,the high definition camera was used to capture the vibration wave,and the video image processing and analysis were carried out based on self-programmed programs.The results show that the self-programmed program can extract the instantaneous displacement of the marked measuring points,the wave velocity is constant during the propagation of the pulse wave,and the wave surface profile can maintain a good shape without deformation.The pulse wave formed by local instantaneous excitation propagates along the conductor to the ends on both sides.After being restrained by the ends,the reflected wave formed on both sides propagates along the conductor.After meeting,the reflected waves formed on both sides overlap each other,causing the conductor vibration.The experimental phenomenon is consistent with the theoretical analysis.