IEC extreme wind

It is possible to select predefined wind time histories corresponding to the IEC extreme wind events (see IEC-61400-3-1 (2019)). For IEC extreme wind, the following parameters can be edited

Extreme wind

IEC extreme wind

Select the type of IEC predefined extreme wind history event.

To see the detailed description of these extreme winds, see IEC extreme events

Options:

ECD:

Extreme coherent gust with direction change.

EDC:

Extreme direction change.

EOG (default):

Extreme operating gust (aka Mexican hat).

EWM:

Extreme wind speed model.

EWSH:

Extreme wind shear, horizontally.

EWSV:

Extreme wind shear, vertically.

Start of extreme wind event

The start time of the extreme wind event in seconds after the start of the simulation.

  • Default value: 5
  • Unit: $\text{s}$
  • Range: 0 — 3600

Ref. wind speed (Vref)

Reference wind speed. Basic parameter for wind speed used for defining wind turbine classes.

  • Default value: 50
  • Unit: $\text{m}/\text{s}$
  • Range: 0 — 100

Ramp-up duration

Duration of ramp-up from initial wind speed to extreme wind speed for the Extreme Winbd Model (EWM).

  • Default value: 10
  • Unit: $\text{s}$
  • Range: 0 — 100

Recurrence period

The Extreme Wind Model (EWM) can be applied with 1 year or 50 year recurrence period.

Options:

1y (default):

Recurrence period of 1 year.

50y:

Recurrence period of 50 years.

Initial speed and angle

Initial wind speed

The initial (horizontal) wind speed at the reference point. The reference point is typically the hub.

If there is no wind shear then this is the initial wind speed everywhere. The wind speed at the reference point can change during the simulation either algoritmically (which is the case for IEC extreme wind and Sine wind) or because of input from you (which is the case for Stepwise Wind).

  • Default value: 10
  • Unit: ${\text{m}} \over {\text{s}}$
  • Range: -100 — 100

Initial angle

The initial angle (direction) of the wind in the horizontal plane relative to North. Clockwise is positive. 0° means that the wind is coming from the North. 90° means that the wind is coming from the East.

The angle can change during the simulation either algoritmically (which is the case for some IEC extreme winds) or because of input from you (which is the case for Stepwise Wind).

  • Default value: 0
  • Unit: $°$
  • Range: -360 — 360

Shear profile

Shear

Decides if a shear law is applied to the deterministic wind.


  • Default value: False
  • Unit: —

Power law exponent

The shear is computed using a power law. This is the power law exponent.

To see how the power law is computed, see Wind profile power law

  • Default value: 0.2
  • Unit: —
  • Range: 0 — 100

Reference height scheme

This parameter lets your define whether the point of application of the reference speed (used to compute a vertical wind shear) is input by you or defined as the hub height. This parameter is only relevant if a shear law is applied to the wind. 

If Hub height is selected, the reference wind speed for the shear will be applied at hub height. If the turbine has multiple rotors, the reference wind speed will be applied at the average hub height. If there is no rotor, the reference speed is applied at the average height of the nodes at sea level. 

Options:

Hub height (default):

The reference height is set to the hub height.

User defined:

The reference height is set explicitly by the user (you).

Reference height

The height above the ground (or above sea level for offshore turbine) where the reference wind speed is applied.

Hub height is often used for the reference height, but in some cases it is convenient to use another height. E.g. if the wind speed is given for a height of 10 m above ground, then this parameter should be set to 10 m. Note: The reference height only has an influence if there is shear (see Wind profile power law)

  • Default value: 10
  • Unit: $\text{m}$
  • Range: 0.01 — 1000