【作者】 王少华；

【导师】 蒋兴良；

【作者基本信息】 重庆大学 ， 电气工程， 2008， 博士

【摘要】 覆冰导线舞动对输电线路安全运行造成了严重危害,国内外学者对覆冰导线舞动机理及防护已进行了大量的研究工作。但是目前对舞动机理的研究多采用传统方法,对目标模型进行简化处理。本文在国内外研究成果基础上,全面考虑影响导线舞动的因素,就其发生机理以及对塔线体系影响进行研究。本文的研究有助于更深入地认识覆冰导线舞动机理及其对输电线路力学特性的影响,对“西电东送、南北互供、全国联网”和超、特高压输电线路的建设和运行具有一定的参考意义。本文首先应用“悬链曲线”理论和“抛物线”理论分别对架空输电线路导线的静力特性进行分析,在此基础上研究了均匀覆冰条件下,风、气温等气象条件对导线静力特性的影响。在“悬链曲线”方法基础上,采用VC++6.0编制了“架空输电线静力特性分析软件”。根据湖北中山口大跨越的实际参数,计算了不同气象条件下其导线张力大小,并分析了气温、覆冰厚度、风速对导线张力的影响。结果表明,冰冻环境下,导线张力和形状的变化大小主要取决于覆冰的变化。根据不均匀覆冰特性,研究了耐张段内不均匀覆冰与不同期脱冰条件下杆塔的不平衡张力。对于各档不均匀覆冰输电线路,当重冰档在耐张段两端时,靠近耐张杆塔的直线杆塔承受的不平衡张力最大;对于各档不同期脱冰线路,当轻冰档位于耐张段中央时,轻冰档的弧垂减小量最大。因此,对于新建的塔线需根据其气象条件对铁塔关键部位进行加固处理。基于流体力学理论,提出了典型覆冰导线——新月形覆冰导线气动特性分析模型的建立方法以及数值模拟方法,并利用该模型与方法计算了覆冰导线周围的空气流场,以及不同覆冰厚度的导线在不同迎风攻角下的升力系数、阻力系数及扭矩系数,得到了覆冰厚度、风速对不对称覆冰导线空气动力参数的影响规律。本方法计算得到的影响规律与现有文献中的影响规律基本一致,验证了本文方法的正确性。从而实现了流体计算代替风洞试验获取覆冰导线的空气动力参数的方法,避免了大量的试验工作,节省了人力和物力。针对传统的单自由度模型忽略扭转方向和水平方向振动、不能获取导线舞动的时程曲线与轨迹的不足,建立了考虑覆冰导线垂直、水平及扭转方向的耦合振动条件下的覆冰导线舞动的三自由度力学分析模型。采用解析法与Simulink仿真相结合的方法对三自由度模型控制方程进行求解,该方法不仅解决了三自由度控制方程的求解问题,还能够直接得到导线舞动轨迹与时程曲线。以湖北中山口大跨越姚双线为例,分析其舞动时程曲线及舞动轨迹。结果表明,当舞动达稳定状态时,垂直方向和水平方向振动波形近似为简谐波。横向振动和扭转振动的频率相一致。从舞动轨迹可以看出,舞动以垂直运动为主,水平方向的振幅较小,舞动轨迹近似斜椭圆。在目前导线张力计算方法基础上,推导了在一个舞动周期内导线水平张力变化量与竖向张力变化量最大值的计算公式,并分析了两个方向的张力变化量最大值与舞动参数及导线参数之间的关系。采用该公式可以估算出舞动发生时导线的水平、垂直方向的最大张力值,为输电塔架等支撑结构的安全设计提供估算方法。从振动平衡方程出发,推导了以振动位移为约束、频率为随机变量的铁塔振动问题的安全边界方程,进而提出了铁塔振动的可靠性设计方法。更多还原

【Abstract】 Icing conductor galloping is of great danger to the safe operation of the transmission line. Both at home and abroad, a lot of research work about the mechanism and protection of the conductor galloping has been done. Based on the research results of the experts both at home and abroad, the mechanism of galloping and the adverse impact on the transmission tower and conductors are analyzed. The research work in this paper will be helpful to the in-depth understanding of the mechanism of the conductor galloping and the influence on the transmission lines. It is also of great reference values to the "West-to-East Power Transmission, South-and-North Transaction and Nationwide Electricity Interconnection" and the construction and operation of UHV and EHV transmission lines.In this paper, based on the“catenary curve”theory and the“parabolic”theory, the static property of the overhead transmission conductors is firstly analyzed, and then the influence of meteorological conditions (such as wind, temperature and so forth) on the static property is also analyzed. Based on the“catenary curve”theory, the software used for the analysis of the static property of the overhead transmission conductors is developed with VC++6.0. Based on the actual parameters of Hubei Zhongshankou large span, the tensile forces and shape of the conductors in different meteorological conditions are calculated, and the impacts of temperature, ice thickness, and wind speed on the tensile force of conductors are analyzed. The analysing results show that, compared with temperature and wind speed, the ice accretion has the greatest influence on the tensile force and configuration of conductors.According to the characteristics of the uneven ice accumulation and the non-contemporaneous ice shedding, the imbalance tensile forces of conductors in the same dead-end section are analyzed. As to the uneven ice accumulation, when the heavy icing spans are in two ends of the dead-end section, the straight-line towers near the dead-end tower bear the largest imbalanced tension. As to the non-contemporaneous ice shedding, when the light icing span is in the middle of the strain section, the arc altitude of the light icing span is the largest. Therefore, the key positions of new established transmission towers should be reinforced according to the meteorological conditions.Based on the the hydromechanical theory, the modelling method and the simulation method for the analysis of the aerodynamic properties of the typical iced conductor (crescent iced conductor) is put forward. The air flow map around the iced conductor is simulated. Besides, as to the iced conductors with different ice thickness, the lift coefficient, drag coefficient and torsion coefficient under different attack angles are calculated. The influence law of ice thickness and wind speed on the aerodynamic parameters of iced conductors can be obtained, which is consistent with that reported in existing related literatures. Consequently, the fluid calculation method can substitute the wind tunnel test to acquire the the aerodynamic parameter of the iced conductors, which can avoid massive test work and save the manpower and material resource.Considering the disadvantage of conventional one-degree-of-freedom galloping mechanism, the three-degree-of-freedom mechanical model considering the iced conductor’s coupling vibration in the direction of vertical, horizon and torsion is put forward. The three-degree-of-freedom control equation is established, and the solving method of combining analysis and Simulink simulation is put forward. The solving method can not only solve the three-degree-of-freedom control equation, but also immediately obtain the time-history curve and galloping track. Take the Hubei Zhongshankou Yao-Shuang transmission line as example, the time-history curve and galloping trace is analyzed. The results show that, under steady galloping state, the time-history curves of the horizontal and vertical directions are approximately simple harmonic waves. The frequency of the transverse vibration is consistent with that of the torsional vibration. It can be seen from the galloping track that, the main vibration is in the vertical direction, the amplitude in the horizontal direction is small, and the galloping track is approximately an oblique ellipse.Based on the existing tensile force calculation method, the calculation formula of the maximum varing quantity of the horizontal tension and the vertical tension component at the suspension poin are deduced. And the influences of the galloping parameter and the line parameter on the tension varing quantity are analyzed. The calculation formula can be used to estimate the maximum varing quantity of the tension in the two directions, which can provide foundation for the design of the supporting structures (such as transimission tower). Based on the balance equation of the vibration, taking the vibration displacement as the constraint and taking the vibration frequency as the random variable, the safe boundary equation of the vibration problem of the transmission tower is deduced, and then the reliability design method is proposed.更多还原