## 4 Analysis of Ice Shedding Response of Overhead Conductors under Strong Winds
### Effect of Wind Attack Angle on the Ice Shedding Response of Transmission Lines  
For a particular icing shape, the initial position of the iced conductor was completely different for different wind attack angles. At the moment of ice shedding, the direction of conductor displacement varied greatly. The displacement curves of the crescent-shaped and D-shaped ice-covered conductors under a 10 m/s wind speed and 45\({}^{\circ}\), 90\({}^{\circ}\), and 180\({}^{\circ}\) wind attack angles are shown in Figure 6. For the crescent-shaped ice conductor, its initial position in the horizontal coordinate of a 45\({}^{\circ}\) wind attack angle was 1.3 m. And the static position difference of the conductor before and after the ice shedding was very small, so the lateral oscillation amplitude was less than 0.3 m. Due to the influence of the initial position, the lateral oscillation direction of the midpoint position of the ice shedding span was the opposite at 90\({}^{\circ}\) and 180\({}^{\circ}\) wind attack angles. Therefore, for horizontally arranged transmission lines, the risk of interphase discharges was different for ice shedding. The static longitudinal coordinates of the conductor before and after ice shedding were very small, and the difference in the longitudinal bounce height of the conductor ice shedding under the two angles of attack was less than 0.7 m.  
As a hypothetical extreme icing morphology, D-shaped icing had a circular arc on the windward side and a plane on the leeward side. When the iced conductor twisted to form a specific wind attack angle, the wind resistance of the iced conductor changed significantly, and its trajectory after ice shedding became very complex, which is more significantly affected by the airflow. As shown in Figure 6, the ice shedding bouncing trajectory of D-shaped icing at a 45\({}^{\circ}\) wind attack angle was very similar to the crescent case at a 90\({}^{\circ}\) wind attack angle. However, due to its larger lift, the longitudinal coordinate of the initial ice shedding position was only \(-\)1.6 m, which was less than the \(-\)3.5 m under the crescent case, and the longitudinal bounce amplitude of the conductor also decreased by 3.11 m. For the 90\({}^{\circ}\) and 180\({}^{\circ}\) wind attack angle conditions, under the action of airflow resistance and lifting force, the longitudinal coordinate of the initial ice shedding position of the conductor was not much different from that of the ice shedding steady state, so the difference in longitudinal bounce amplitudes was also very small. As shown in Table 1, the difference in airflow resistance corresponding to the D-shaped iced conductor at 90\({}^{\circ}\) and 180\({}^{\circ}\) was very great, so the transverse coordinates of the initial ice shedding position of the conductor were 0.52 m and 8.22 m, respectively. After ice shedding, the transverse motion of the conductor corresponding to the two wind attack angles was completely opposite, and the amplitudes were 1.22 m and 11.71 m, respectively, which increased the discharge risk of horizontally arranging conductors caused by ice shedding bouncing.