高压交直流同塔输电线路无线电干扰与可听噪声的计算

为了寻求一种适合交直流同塔架设线路的无线电干扰与可听噪声计算方法,从理论上分析了混合线路表面场强的特点,利用线性叠加原理求出混合线路表面场强,并结合晴天和雨天对交流和直流线路电晕程度的不同影响,提出在同一种天气状况下计算交直流线路无线电干扰与可听噪声。用3种计算无线电干扰与可听噪声的方法,分晴天和雨天情况进行计算比较,结果表明3种方法中BPA修正公式计算值最大,该方法可视为目前计算交直流同塔线路无线电干扰与可听噪声的有效方法。     

基于广义谐振理论的输电线路中波无源干扰谐振频率预测

现有IEEE（institute of electrical and electronics engineers）标准,目前只能明确0.5~1.7 MHz有限频段的输电线路无源干扰谐振机理。为拓展输电线路无源干扰谐振的研究频率,引入广义谐振理论,提出了一种基于电磁场能量平衡的干扰谐振频率预测构想。将大尺度空间下输电线路铁塔阵列及天线等效为广义封闭系统,从而基于复坡印廷定理,推导了电磁开放系统广义谐振因子的表达式,求解得到的广义谐振因子零值点为无源干扰谐振频点。该方法由于避开了传统将铁塔等效为半波天线的局限,因此可以实现中波频段无源干扰谐振预测。采用IEEE标准算例进行验证,结果表明：1.7 MHz频率以下,基于广义谐振理论的无源干扰谐振频率预测值和缩比模型实测值最大误差不超过±0.169 MHz。     

Simulation of ice shedding on transmission lines considering ice shedding velocity effect

Ice shedding on transmission lines results in longitudinal unbalanced forces on adjacent transmission towers,which significantly threaten the safety of transmission lines.The methodology of ice shedding simulation on transmission lines is developed by using the finite element method and validated by comparing the simulation results with those obtained from the model scale experiments done by previous researchers.The responses of the tower line system induced by simultaneous ice shedding on the conductor and ground wire are analyzed.The developed methodology is then applied to study ice shedding considering unzipping effect,in which the influence of the velocity of ice shedding on the responses is investigated.Results from this study show that the longitudinal unbalanced forces induced by simultaneous ice shedding from the ground wire are greater than those from the conductor under similar condition.During the analysis of ice shedding considering unzipping effect,the slower the velocity of ice shedding is,the closer the responses are to those resulting from static unloading;and the faster the velocity of ice shedding is,the closer the responses are to those resulting from simultaneous ice shedding.