导线倾角与覆冰过程扭转因素对覆冰形状特性影响研究

Study on Influence of Conductor Inclination Angle and Twisting Factors of Icing Process on Ice Shape Characteristics

输电导线覆冰严重威胁电网运行安全,准确预测导线覆冰形状和增长趋势,可以有效预防次生灾害的发生.已有输电导线覆冰增长预测模型较少考虑覆冰偏心扭转对导线表面覆冰形状的影响.为此,综合考虑覆冰偏心、风速等对导线的耦合扭转特性,建立输电导线动态扭转覆冰预测模型.基于预测模型对导线表面覆冰形状进行预测模拟并与文献实验数据对比,验证了模型的有效性.利用预测模型,进一步讨论导线倾角及温度、风速和MVD(水滴中值直径)对冰形和扭转速度的影响.研究发现,导线迎风面覆冰厚度随着倾斜角度的增加,分层现象逐渐明显.与水平布置(零倾角)导线对比,倾斜角度为60°时,导线覆冰面积分别增加18.26%(覆冰125 min)、26.30%(覆冰245 min),扭转角度分别增加10.4°(覆冰125 min)、16.2°(覆冰245 min),冰形呈“沟壑”状.

Transmission conductors icing is a critical threat to the safety of power grid operation.Accurate prediction of the ice shape and growth trend of conductors icing can effectively prevent the occurrence of secondary disasters.Existing models for predicting the ice growth of transmission conductors seldom consider the effect of ice eccentricity torsion on the ice shape of transmission conductors.Therefore,the dynamic torsional icing prediction model of transmission conductor is established by considering the coupling torsional properties of transmission wire,such as ice eccentricity and wind speed.Based on the prediction model,the ice shape on the conductor's surface is simulated and compared with experimental data in the literature,and the validity of the model is verified.The effects of conductor inclination and temperature,wind speed,and MVD(median diameter of raindrops)on ice shape and torsional speed are further discussed with predictive models.It is found that the stratification of the ice thickness on the windward side of the conductor is gradually obvious with the increase of the tilt angle.Compared with the horizontal arrangement(zero inclination)conductor,when the inclination angle is 60°,the ice area of the wire increases by 18.26%(ice covering 125 minutes)and 26.30%(ice covering 245 minutes),and the torsion angle increases by 10.4°(ice covering 125 minutes)and 16.3°(ice covering 245 minutes),respectively,and the ice shape is"ravine".