Danish machining company CNC Onsite has developed a patented method for repairing, not replacing, yaw rings on wind turbines on site. The process doesn’t require disassembly on the turbine rotor and nacelle necessary for replacing yaw rings.
The teeth on yaw rings can wear down over time, and they’re necessary components for power production.
“This inspired us to develop a repair method as an alternative,” Søren Kellenberger, sales director of CNC Onsite. “We can now offer a repair service for both onshore and offshore at a fraction of the cost of replacing the entire yaw ring, and that makes it viable to keep perfectly good wind turbines operating for longer.”
The CNC Onsite method requires removing and reinserting machined teeth on yaw rings. Mounted at the top of the wind turbine tower, the toothed yaw ring is a gear that engages with motors mounted on the nacelle to align the rotor blades with the wind.
CNC Onsite estimates that turbines on some 5 to 10% of wind farms will experience damage to their yaw ring teeth during their service life. Typical causes include unpredictable wind events or uneven loads sustained over time.
“The process we apply when creating new yaw ring teeth for a wind turbine is similar in principle to a new dental crown that is first copied precisely then fitted by a dentist using precision tools,” Kellenberger said. “The aim is the same, and it should last for a long time.”
These repairs are conducted inside the turbine tower, so the work can be done in inclement weather.
“As long as it is safe to travel to and access the wind turbine, we can carry out the repairs. So there are far fewer days when we cannot work. This is also good for both work schedules and costings,” Kellenberger explained.
Replacing the yaw ring requires the entire nacelle to be detached using a crane. The system developed by CNC Onsite can usually carry out yaw ring repairs within a few days.
“We’re eliminating the need for manufacturing a new yaw ring and above all the huge logistical effort required to transport a yaw ring to the site, deploy cranes, which is particularly tricky offshore, and replace it,” Kellenberger said. “Such an operation requires a significant number of people and a lot of equipment with all the associated CO2 emissions. With our repair method,this is no longer required.”
The yaw ring repair service offered by CNC Onsite has already been used on a range of turbines in wind parks, both offshore and onshore, since it entered the market in 2019 following many months of endurance tests, proving that the replaced teeth are robust over time.
“The fact that whenever you take down the nacelle there is a potential risk of damage to it and especially to the blades which is another factor that cannot be ignored,” Kellenberger said.
News item from CNC Onsite
Filed Under: Components, News, Pitch & yaw