4.6 KiB
Theory manual
!
Demanded Generator Torque is reached at point D, the torque demand is kept constant for all higher wind speeds. Once the Demanded Generator Speed is reached the pitch control regulates the rotor speed. This is know as the full load regime. A small (optional) margin is allowed between points D (where the torque reaches maximum) and E (where pitch control begins) to prevent excessive mode switching between below and above rated control modes. However, this margin may not be required, in which case points D and E coincide. The line CD may collapse to a point if also desired.
In the full load regime, the blade pitch is adjusted to maintain the chosen operating point, designated E. Effectively, changing the pitch alters the lines of constant wind speed, forcing them to pass through the desired operating point.
The pitch angle is limited to the Minimum pitch angle the lower limit of pitch or aileron deployment angle. The Maximum pitch angle that is the upper limit of pitch or aileron deployment angle. There is also an option to schedule pitch angle against hub wind speed during the initial condition calculation.
The user can select between Pitch feathering or Assisted stall to specify the direction of pitching. If pitch feathering is selected, the Minimum pitch angle will be set for normal operation below rated wind speed, and the pitch (or aileron) angle will increase above rated. If Assisted Stall is selected, the maximum pitch setting is used below rated, and the pitch (or aileron) angle decreases (or moves to more negative values) above rated.
The feature allows the user to easily specify pitch angles below rated wind speed for initial conditions. This is useful for model linearisation calculations. For above rated wind speeds, the initial condition algorithm finds a pitch angle that maintains maximum rotor speed. However, the minimum pitch angle set by the pitch scheduling routine is still used as the minimum angle even though a smaller angle might be needed to maintain the maximum rotor speed. Furthermore, it provides a convenient method for matching the behaviours in the initial condition algorithm and a time domain pitch scheduling routine implemented in a User-Defined Controller. Note that this feature only supports VSPR control strategies, and does not support the “Assisted Stall” type controller. In addition, this option only applies when the turbine is in power production mode.
The user can specify hub wind speeds and minimum pitch angles in a lookup table. During the initial condition calculation, a linear interpolation of the data points is utilized to calculate the minimum pitch angle for the current hub wind speed (both above and below rated wind speed conditions). The points in the lookup table must be in a monotonic ascending order and if the current hub wind speed is out of range of the specified lookup table the nearest value will be used.
user manual
The steady state parameters define the operating envelope of the turbine, and are required for calculation of the steady power curve and steady operational loads. Click on Controller Dynamics to define additional parameters which model the dynamic action of the controller, such as controller gains and transducer and actuator time constants.
!
Steady state parameters
- Demanded electrical power: the power set-point, i.e. the electrical power output required above rated wind speed.
- Minimum pitch angle: the lower limit of pitch or aileron deployment angle.
- Maximum pitch angle: the upper limit of pitch or aileron deployment angle.
- Select Pitch feathering or Assisted stall: to specify the direction of pitching. If Pitch Feathering is selected, the Minimum pitch angle will be set for normal operation below rated wind speed, and the pitch (or aileron) angle will increase above rated. If Assisted Stall is selected, the Maximum pitch setting is used below rated, and the pitch (or aileron) angle decreases (or moves to more negative values) above rated.
!
BEMSolve(twist) --> phi、Pn、Pt
Solve_along_blade(V, omega) -> Cp、Power、Thrust
aoa = phi - twist
new_twist = twist + pitch_angle
delta_pitch_anlge - >
0
0 + 1
0 + 1 + 1
19.006