1. Specification of internal control system for nacelle yaw

1.1. Description of internal control system

Only internal yaw control is currently available. See Wind turbine specification for a description of how to set up the model to use yaw control.

The yaw error is found as the relative angle between the instantaneous wind at the hub and the orientation of the shaft. The controller starts aligning the rotor- nacelle assembly when a user defined threshold of the integral of the squared yaw error is reached. This gives more active response to fast changes in the yaw misalignment. The controller uses a constant, user defined yaw rate to get back to zero misalignment, or to a user defined yaw error.

The input yaw error and the output yaw angle are low pass filtered with a fast and a slow corner frequency, respectively.

The yaw controller logics follow the yaw rate controller described by Mulders and van Wingerden (2018).

Yaw controller configuration input version number
yawconfinput_ver

  • yawconfinput_ver: integer > 0: Yaw controller configuration input version number. Current version is 1.

Yaw controller time step
DT_yawcontrol

  • DT_yawcontrol: real > 0: Yaw controller sample interval \(\mathrm {[T]}\)

Yaw set point
YawErrSetPoint

  • YawErrSetPoint: real [-180, 180]: Specified nacelle yaw misalignment \(\mathrm {[deg]}\)

Yaw rate
YawRate

  • YawRate: real > 0: Rotational velocity for yaw engine \(\mathrm {[deg/T]}\)

Yaw misalignment threshold
YawErrThresh

  • YawErrThresh: real > 0: Integral threshold for activation of yaw engine \(\mathrm {[deg^2T]}\)

Fast filter corner period for low pass filtering
T_LPfiltFast

  • T_LPfiltFast: real > 0: Fast filter corner period for input signal \(\mathrm {[T]}\)

Slow filter corner period for low pass filtering
T_LPfiltSlow

  • T_LPfiltSlow: real > 0: Slow filter corner period for output signal \(\mathrm {[T]}\)

yaw misalignment
Figure 1. Definition of (positive) yaw misalignment between wind direction and shaft orientation
Example input for internal yawcontrol system
'yawconfinput_ver
1
'DT_yawcontrol         Yaw controller time step (s)
0.005
'YawErrSetPoint        Yaw set point (deg)
0.
'YawRate               Controller yaw rate, (deg)
0.5
'YawErrThresh          Yaw misalignment threshold, (deg^2 s)
1.0
'T_LPfiltFast          Fast filter corner period for low pass filtering (s)
1.0
'T_LPfiltSlow          Slow filter corner period for low pass filtering (s)
60.0