Description
The nonlinear controller data file contains parameters that define the controller settings and performance. In addition to control gains, the data file describes upper and lower limits on output signals, floating feedback control settings, and reference values for wind turbine operation.
The nonlinear controller regulates rotor speed and output power for fixed-based or floating wind turbines by actuating blade pitch and generator torque. The control operation can be divided into 2 regimes:
- Regime 2: Wind speed is below the rated value, so control focuses on maximizing power extraction.
- Regime 3: Wind speed is above the rated value, so control focuses on maintaining the rated rotor speed and power.
Parameters
| Name | Description | Value | Unit |
|---|---|---|---|
Pref |
Reference power. | Real scalar | [W] |
UlowHysteresis |
Low hysteresis threshold of the regime switching logic. | Real scalar | [rad/s] |
UhighHysteresis |
High hysteresis threshold of the regime switching logic. | Real scalar | [rad/s] |
Kt |
Gain value of torque controller. | Real scalar | [N.m.s²/rad²] |
R3TorqueKgain |
Torque gain for regime 3. | Real scalar | [W.s/rad] |
TorqueMin |
Minimum value of output torque. | Real scalar | [N.m] |
TorqueMax |
Maximum value of output torque. | Real scalar | [N.m] |
TorqueMinRate |
Minimum value of output torque rate. | Real scalar | [N.m/s] |
TorqueMaxRate |
Maximum value of output torque rate. | Real scalar | [N.m/s] |
Kp2Pitch |
Proportional gain of pitch controller in regime 2. | Real scalar | [1/s] |
Kp3Pitch |
Proportional gain of pitch controller in regime 3. | Real scalar | [s²/rad] |
Ki3Pitch |
Integral gain of pitch controller in regime 3. | Real scalar | [s/rad] |
LowerBeta |
Minimum value of output blade pitch. | Real scalar | [rad] |
UpperBeta |
Maximum value of output blade pitch. | Real scalar | [rad] |
BetaMinRate |
Minimum value of output pitch rate. | Real scalar | [rad/s] |
BetaMaxRate |
Maximum value of output pitch rate. | Real scalar | [rad/s] |
FloatEnable |
Enable the floating feedback control. | Boolean (0/1) | [0/1] |
FloatKp |
Proportional gain of floating feedback controller. | Real scalar | [-] |
FloatLPFOrder |
Order of the low-pass filter. | Positive integer | [-] |
FloatLPFCutoff |
Cut-off frequency of the low-pass filter. | Real scalar | [Hz] |
FloatHPFOrder |
Order of the high-pass filter. | Positive integer | [-] |
FloatHPFCutoff |
Cut-off frequency of the high-pass filter. | Real scalar | [Hz] |
Notes
The nonlinear controller data is stored in a .txt file that can easily be produced using the Data Generation Tool or by populating a .txt file manually. If the file is created manually, parameters must be defined in the format name = value;, where name is the parameter name and value is a number of type Real (although booleans expressed as 1 or 0 and integers are still accepted). Comments can be inserted in the file using double slash: //. See below for an example.
// =============================================
// Inertial properties
// =============================================
m = 123.456; // mass [kg]
I_xx = 1.23e4; // mass moment of inertia [kg.m²]
// =============================================
// Geometric properties
// =============================================
l = 12.345; // length [m]
The block diagram illustrates the control algorithm of the nonlinear controller. The control algorithm switches between regime 2 and regime 3 based on the switching condition. To ensure a smooth transition between the two, a setpoint smoother block is integrated with the switching logic to avoid abrupt changes during the transition.
