Questions on PA_Mode, LPF Corner Frequency, and Signal Filtering in Control Code

[mohsamaz]

Hello everyone,
I am currently trying to better understand some aspects of the control code and would be very grateful if you could help me clarify a few points:

1-What is the function of PA_Mode?

Does it apply a filter if we assume that we have actuators and some noise should be filtered?

Or is it meant to model response time delays and physical inertia?

If yes, for example, for a first-order filter, is F_LPFCornerFreq = 1.57080 appropriate for all LPFs in the control code?

As far as I’ve read, it is 1/4 of the blade’s first edgewise natural frequency. Is it also appropriate for filtering generator speed?

2-How can we justify that this value is acceptable for all cases?

3-Is generator speed filtered by an LPF? If so, where in the code?

4-How can one apply different corner frequencies for different purposes?

5-In SUBROUTINE IPC, what does “Optionally filter the resulting signal to induce a phase delay” mean?
What is the purpose of this?

Best regards,

[dzalkind]

PA_Mode is supposed to model an actuator's delay and physical inertia, if there's not an actuator in the turbine model. This is intended to have a physical meaning.

F_LPFCornerFreq is a filter in the control code that is part of the software, not physics of the model. It is automatically determined in the rosco toolbox for each turbine as you suggest. The input is here.

Filters can be found here.

This paper has a good overview of IPC and phase delays between the tilt/yaw moment that occur in flexible rotors.