A wind turbine is a complex machine with many moving parts compared to a solar plant which has fewer moving parts. Wind turbines can be segmented into onshore and offshore wind turbines. While the operating principle is the same, onshore wind turbines are smaller in MW size compared to offshore wind turbines. Also it is easier to perform operation and maintenance activities on onshore wind turbines.
Onshore Wind turbine – Failure Rate of Subsystems
Based on data collected over 13 years from thousands of onshore wind turbines in Europe, two studies found the following insights:
- Some of the electrical sub-systems fail more frequently but they are easy to fix. Pitch system, yaw system, converter have higher failure rates but they can be fixed in a a couple of days.
- Mechanical rotating equipment i.e. generator and gearbox fail less frequently but they take the longest time (up to 2 weeks) to fix once they fail. So turbine availability numbers suffer when drive train equipment fails.
Offshore Wind turbine – Failure Rate of Subsystems
Studies of offshore failure rates are less comprehensive. One study from Egmond wind farm in the Netherlands comprising of 36 Vestas V90-3MW turbines shows downtime caused by various sub-systems below:
The above chart also shows similar pattern as the one for onshore wind farms – Control, yaw, pitch systems cause more turbine stops but less downtime because they can be rectified quickly. However issues with generator or gearbox are less common but take the longest time to fix.