Icing on wind turbine blades

Severe rime ice accretion on the leading edge of the wind turbine blade.

Wind turbines can encounter different types of atmospheric icing depending on the conditions.

Different ice types can accrete on the leading edges of the wind turbines, and these ice types are mainly formed from in-cloud icing events; clouds and fog containing supercooled droplets hits the turbine blade, and the icing occurs. Depending on the droplet size in the clouds or fogs rime or glaze is formed on the leading edge and nearby areas of the blades.

Ice formations on the wind turbines inflict severe problems on operation; reduces lifetime and causes power losses. Ice formed on the blades and other parts of the turbine causes increased load on the turbine structure, which can in the worst case lead to failing on the wind turbine. In some cases the ice formation on the leading edge of the blade can lead to shutdown of the whole turbine. Ice accretion on the leading edge also affects the aerodynamic performance of the wing. Accreted ice changes the aerodynamic balance of the blades, which reduces drag coefficient that increases power losses. Even a small ice accretion on the blade will change the surface roughness of the blade, which can cause power losses due to changed aerodynamic behavior.

Standstill time can be reduced by applying different de- and anti-icing methods. By using de-icing methods the accreted ice can be melted during the standstill. Heating resistance based anti-icing methods can be operated during turbine operation.

One important aspect concerning icing in wind turbines is ice throw risk. Different size ice pieces can plunge far away from the turbine, which causes risk to nearby infrastructure and can inflict serious damage to people and structures in the nearby areas. Ice falling off from turbine also hinders the accessibility of maintaining personnel to wind turbine. Proper risk assessment is required in wind turbine installations.