多分裂输电导线垂向-扭转耦合诱发脱冰与非线性时变振动机理及特性研究

The impact force and large amplitude vibration, due to sudden ice shedding, is one of the main factors causing damage of electrical transmission lines structures. In previous studies, the natural vertical-torsional coupled induced ice shedding effect and the resulting variation of system mass, stiffness and damping are rarely studied, as leads to insufficient precision of the dynamic response of the bundled conductor following ice shedding. This underestimates the adverse influence of ice shedding and the faults due to ice shedding occurs frequently. This project focuses on the vertical-torsional coupled induced ice shedding effect and nonlinear time-varying vibration of bundled conductors. The study includes the following aspects: deduce the critical condition of vertical and torsional induced ice shedding after initial ice shedding of bundled conductors, analyze the time-varying features of the dynamic system, establish the vertical-torsional coupled induced ice shedding and nonlinear time-varying vibration model of bundled conductors, design and conduct physical induced ice shedding tests, analyze the influence of main factors on induced ice shedding and nonlinear time-varying vibration, and propose available measures to suppress the large amplitude vibration and bundle collapse after ice shedding. This study can provide theoretical support for the structure design and ice shedding vibration control of extra and ultra high voltage transmission lines, which is essential for the safety of electric grid.

输电导线上覆冰突然脱落引起的冲击荷载和大幅振动，是造成线路结构机械损伤的主要原因之一。以往研究较少关注多分裂输电线路上覆冰脱冰过程中真实存在的垂向-扭转耦合诱发脱冰效应和由此引发的动力系统质量、刚度和阻尼时变特性，导致得到的多分裂导线脱冰动力响应计算精度较低，低估了脱冰跳跃的真实危害，使得脱冰引起的线路故障仍不断发生。本项目拟对多分裂输电导线垂向-扭转向耦合诱发脱冰和非线性时变振动的产生机理进行基础科学研究，具体包括：推导初始脱冰冲击下多分裂导线垂向和扭转向诱发脱冰临界条件，分析动力系统的时变特性，建立多分裂导线垂向-扭转耦合诱发脱冰与非线性时变振动分析模型，设计并开展诱发脱冰物理模型试验，分析各主导影响因素对诱发脱冰和非线性时变振动特性的影响规律，提出多分裂导线脱冰大幅振动和扭转失稳的抑制措施。本项目可为超/特高压多分裂输电线路结构设计和脱冰振动控制提供理论支撑，为电网安全提供保障。

多分裂导线是超/特高压等电网骨干输电线路普遍采用的导线型式，是实现“西电东送”、“大规模可再生能源外送”等国家重大能源输送战略的载体。尤其近年来，受我国雨雪冰冻灾害频发影响，脱冰跳跃已成为制约我国超/特高压骨干网架结构安全的技术瓶颈之一。与单导线相比，多分裂导线更易受诱发脱冰影响，且由于受其特有的垂向脱冰与扭转脱冰的耦合、垂向振动与扭转振动的耦合、子导线不均匀覆冰、不同步脱冰、间隔棒布置方案等因素的联合影响，使其诱发脱冰效应和脱冰后的动力响应也呈现出更为复杂和独特的非线性时变特性。然而，其耦合诱发脱冰和耦合振动的机理及特性尚不清晰，亟待开展深入系统研究。本项目推导了多分裂导线垂向和扭转向诱发脱冰临界条件，揭示了多分裂导线垂向-扭转耦合诱发脱冰机理，建立多分裂导线垂向-扭转耦合诱发脱冰与非线性时变振动数值仿真模型，在多分裂输电导线脱冰动力响应的研究中考虑诱发脱冰效应和垂向-扭转耦合效应的影响，揭示了关键因素对多分裂导线诱发脱冰过程及其非线性时变振动特性的影响规律，设计并开展了多分裂导线诱发脱冰试验，验证了考虑诱发脱冰的必要性，根据分裂导线脱冰抑制需求，结合特高压输电线路工程防脱冰跳跃设计需要，研究提出了多分裂导线脱冰跳跃抑制和差异化设计技术方案。项目成果将有助于提升多分裂输电导线脱冰动力响应的计算精度，为多分裂输电线路的结构设计、抗冰灾能力提升和现行输电线路设计规范的改进提供理论基础，对保障超/特高压电网的安全稳定运行具有重要工程价值。

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