特高压输电线路动态风偏响应及参数影响分析

Dynamic wind-induced swing response and parameters' influence analysis of UHV transmission lines

输电线路风偏响应与线路结构参数密切相关,研究特高压输电线路的风偏响应规律有助于防范闪络事故的发生。通过风洞试验测定特高压输电线路八分裂导线和绝缘子串的气动力参数。建立连续多跨特高压输电线路风偏响应分析的两阶段频域法,即先以非线性有限元静力计算确定平均风作用下的导线静态风偏响应,随后以该状态下导线的构型和刚度为初始条件,引入考虑面内振型影响的气动阻尼,在频域中通过线性动力计算方法进行导线的脉动风偏响应计算。该两阶段频域法与直接时域法相比计算效率大为提高,同时可保证计算精度。以特高压1000kV南荆I线为研究对象,构建四跨导线-绝缘子串有限元模型,考虑到连续多跨导线频率密集和模态复杂的特点,以能量法确定参与模态数,详细分析不同档距、挂点高差和运行张力条件下绝缘子串风偏角的变化规律,并分析规范中刚性直棒法的不足。结果表明,当线路杆塔存在高差时,呼高低的塔处于风偏的不利位置,更易发生风偏闪络事故;低呼高塔的绝缘子串风偏角会随着相邻塔呼高和线路运行张力的增大而增大,但随着相邻档档距的增加略有减小。相较于档距的变化,风偏角对挂点高差的变化更为敏感。

Wind-induced swing of UHV(ultra high voltage) transmission lines is easily influenced by structure parameters, thus it is conducive to study the relationship between so as to prevent the flashover accidents. The aerodynamic parameters of eight-bundled conductors and insulator strings were measured by the wind tunnel test.Frequency-domain method for wind-induced swing analysis of multi-span continuous UHV transmission lines was performed in two steps. Firstly, the mean response was studied by the non-linear static analysis. And then the fluctuating response was investigated by the linear analysis in frequency domain, taking the configuration and stiffness in static state as initial condition and introducing the aerodynamic damping which considered the influence of in-plane modes. Two-step frequency-domain method is more efficient than time domain method with high accuracy. Aiming at the UHV 1000 kV Nan-Jing line I, a four-span wire-insulator FEM was established.Taking intensive natural frequencies and complex models of multi-span conductors into consideration, the number of participant models was determined by the energy method. Using frequency-domain method in two steps, the mean and fluctuating wind-induced swing responses were figured out with different structure parameters and the rigid rod method recommended by the standard was proved to be lack of accuracy. Research results show that if there is height difference in the transmission line, towers with low nominal height are more likely to suffer flashover accidents. The wind-induced swing of towers with low nominal height increases as nominal height of adjacent towers and the working tension, while it decreases with the span. Compared with the change of span, the wind-induced swing is more sensitive to the change of altitude difference.