Repairing lightning damage on a wind turbine in Scotland

Owing to their great height and their location on flat plains with nothing much else around them, wind turbines are lightning magnets and strikes can cause significant damage. This damage can include exploding blades or fried generators and control system electronics. Though turbines are designed to withstand a certain amount of lightning, there is always a risk that their limits may be exceeded. When lightning damage occurs, it is important to repair it quickly due to the loss of earnings while the turbine is shut down. Repairs can be complex, requiring a special methodology of access to repair the damaged part or the complete removal of the blade from the turbine.

In March 2021, RSK company CAN Renewables was asked by a client to perform blade repair work on four wind turbines, one of which had been damaged by lightning strikes, at a site in Scotland. The project came with a tight deadline, as the client requested that this work was carried out before the end of the financial year. The damage caused by the lightning consisted of the glass fibre layers splitting apart due to a strike to the blade that narrowly missed the lightning protection system’s external receptor and hit the internal system under the surface.

The lightning strike repair work presented two particular challenges: the first was the weather, as many composite repair materials for wind turbines can only be used within certain temperature or humidity parameters. To solve this, we sourced a new product and method to carry out the repairs in cold and high humidity conditions. The second challenge of this project was assembling a team at short notice with all the materials required for the repairs. CAN Renewables mobilised two qualified blade repair technicians to complete the work using a truck-mounted mobile elevated work platform.

We removed all the damaged layers to expose the extent of the required repair. Our technicians then measured up the areas that needed repair with fibreglass and epoxy resins. Once they had applied the new layers of glass fibre, the technicians then enclosed the area in an airtight covering. When the area was sealed, they then removed all the air using a vacuum pump. This removed any air from the glass fibre and bonded all the freshly applied layers together. Once the vacuum was running, the technicians applied a heat blanket on a high heat setting over the area to cure the resin.

Once the resin was cured, they then applied filler to the whole area and allowed it to cure, then sanded it to the correct profile of the blade. During this repair, they removed the lightning protection system receptor, tested it for resistance and reinstalled it. Our technicians applied a two-part topcoat to the area once the repair was complete.

The repair work on all the turbines was completed within the tight deadline, thanks to CAN Renewables’ innovative thinking and the fast mobilisation of engineers.