An underappreciated part of your wind turbine system, the pitch actuator is mainly responsible for adjusting the wind turbine pitch angle. But when the pitch actuator faults (often through no fault of its own), the dynamic response of the pitch angle either slows down or fails altogether.
The result? Your control system can’t control your system anymore. That’s why real-time fault diagnosis is critical for wind turbine control systems.
Wind Turbine Pitch Actuators & Finding Faults
In a perfect world, your wind turbine pitch system is simply worrying about regulating blade pitch angles. The controller’s job is to maintain the wind turbine power at a consistent level based on wind speed.
The days of that being the only job of your pitch actuator are over. An advanced pitch actuator system reports faults in real time through exhaustive data analysis. It uses that data to advise your control system when conditions call for an adjustment or even a shutdown.
A sophisticated pitch actuator system should be able to take proper corrective action according to need and priority.
How the Pitch Actuator Collaborates With Your Control System
An important part of fault diagnosis is being able to understand the message the system is conveying. Let’s say you’re sitting in Houston and looking at your SCADA system. Those 30-ft. monitors are showing weather conditions, the grid network, and a map of the turbine site.
The actuator will report to the main turbine controller about the conditions going on inside the turbine. This may be a reflection of:
Conditions of a bearing
Conditions of the drivetrain
The actuator system is continuously outputting data from the turbine. That information goes to the main controller, which can then pass it on to the SCADA system. If any of these factors become a danger to the safe operation of the turbine, a good pitch actuator will diagnose that and warn you ahead of time.
So, you can be in Houston looking at a turbine in Kansas and seeing that the temperature or actuator torque is off a bit, for example. A mouse click on that turbine and you get a dashboard of the operating behavior in real time. And your pitch actuator will say, “Hey, look at this! It needs your attention.”
That’s the value of an advanced pitch actuator: It’s a warning system that can mitigate or even avoid a fault.
Note that pitch actuators fault when they're trying to protect themselves from outside influences. You can, for example, have an encoder failure on the turbine’s main generator -- that will make the pitch actuator fault. It’s an SOS signal from the actuator rather than a problem with the actuator itself.
Cost Impact of Fault Diagnosis
Complacency with “nuisance alarms” that are acknowledged but never fixed can lead to much larger issues. If you don't get that warning in a timely manner -- or it is ignored -- your turbine could sustain:
A broken drivetrain
A broken pitch actuator
Another issue that requires shutdown and maintenance
Shutdowns mean you’re not producing wind energy. Maintenance usually has the same impact. Both can be mitigated by a high-performing pitch actuator system.
Best Practices for Fault Diagnosis
The strategies for keeping a wind turbine running continue to develop as technology in the field grows. Here are a few diagnosis basics:
Start at one side of the circuit and not somewhere in the middle.
Don’t jump around. Use the linear method of troubleshooting.
Think about what the circuit is doing compared with what it’s supposed to do.
For more cutting-edge diagnosis strategies for avoiding the unthinkable, check out this post on modern fault avoidance.
It All Starts With the Pitch Actuator System
To recap, these are the dangers of failing to address fault diagnosis needs, from least to most severe:
Loss of efficiency
Loss of availability
Loss of turbine(!)
Again, the cost-efficient way to maintain turbine health is to take preventative steps so you have fewer faults to begin with. Purchasing a better, more advanced pitch system, for example, may cost more initially but save you from downtime and repairs in the long run.