直流电场下特高压背风子导线过冷雨滴碰撞系数研究

Research on Collision Coefficient of Super-cooled Raindrops on Ultra High Voltage Leeward Conductor Under DC Electric Field

特高压直流输电线路在高海拔或低气温环境下易发生覆冰现象。由于迎风与背风导线的间距较小,雨滴轨迹及背风导线流场会受到迎风导线的影响。然而,针对碰撞系数或覆冰特性的研究多集中在单根导线风场大小、雨滴粒径等关键参数,鲜见涉及电场条件下分裂导线背风子导线碰撞系数的讨论。为此,结合拉格朗日法对雨滴撞击背风子导线表面的过程进行数值分析。利用ANSYS Fluent中的电磁场模块对分裂导线施加电场,分析了电场强度、导线间距及导线夹角等参量对碰撞系数的影响。研究表明:电场强度在0~50 kV/cm的范围内,导线碰撞系数几乎呈线性衰减,衰减率约为55%;电场场强大于50 kV/cm时,碰撞系数衰减幅度进一步增大。随着导线间距的增加,背风子导线的碰撞系数逐渐升高,随后保持不变。导线夹角不为0°时,风速4 m/s工况下的碰撞系数平均值约为0.6543,最大幅度为1.9%,风速10 m/s工况下的碰撞系数平均值约为0.8395,最大幅度仅为1.2%,碰撞系数几乎不发生改变。

Ultra High Voltage(UHV)transmission lines are prone to icing at high altitude or low temperature.Due to the small spacing between the windward and leeward conductors,the raindrop trajectory and the leeward conductor flow field will be affected by the windward conductor.However,the research on the collision coefficient or icing characteristics mostly focuses on the key parameters such as the wind field size of a single conductor and the particle size of raindrops,and there is little discussion on the collision coefficient of the leeward sub conductor of the split conductor under the condition of electric field.In this study,the process of raindrop impacting the surface of leeward sub conductor is numerically analyzed combined with Lagrange method.The electromagnetic field module in ANSYS Fluent is used to apply an electric field to the split conductor,and the effects of parameters such as electric field strength,conductor spacing and conductor angle on the collision coefficient are analyzed.The research shows that when the electric field strength is in the range of 0~50 kV/cm,the conductor collision coefficient decays almost linearly,and the attenuation rate is about 55%.When the electric field strength of the conductor is greater than 50 kV/cm,the attenuation range of the collision coefficient increases further.With the increase of conductor spacing,the collision coefficient of leeward sub conductor increases gradually,and then remains unchanged.When the included angle of the conductor is not 0°,the average value of the collision coefficient under the condition of wind speed 4 m/s is about 0.6543,with a maximum range of 1.9%.The average value of the collision coefficient under the condition of wind speed 10 m/s is about 0.8395,with a maximum range of only 1.2%,and the collision coefficient hardly changes.