Designing a Wind Turbine: Dealing with Resonance

Whenever the natural frequency of a turbine tower meets the rotor or blade frequency, it oscillates. It has a resonance. How do we avoid it?

Since it’s already commissioned, you can’t do much about the design.

You can only control the speed of the rotor. In this case, you just need to make sure it doesn’t stay at that frequency for long. Let’s say at 9 mm/sec, the natural frequency of the tower meets that of the rotor or blade. Make sure the control system makes it either pitch in or pitch out and not stay at that speed for more than 5 to 10 seconds.

You might see 1,000 startups per year. That means you might see resonance 1,000 times per year, reducing the life of the turbine. So try to reduce those effects by using the pitching algorithm of the blades to pitch in or pitch out and make sure that the tower does not oscillate for long. Also, you can reduce or increase the rotor torque.