Campbell Diagram

The Campbell diagram feature performs a calculation of the coupled modes of the complete aeroelastic system and their characteristics, such as frequency, damping, and composition based on contributions from blade modes, tower (or support structure) modes, and other system degrees of freedom. An advanced procedure is used for joining the coupled modes across the operating points. The resulting Campbell diagram, showing the coupled mode frequencies against rotor speed at all operating points, can be plotted using the DataView screen. The resulting coupled modes can be visualised using the Coupled Mode Animator, if the Output coupled mode animations data option is enabled.

There are three main modes of turbine operation for Campbell diagram analysis:

• Power production: Wind speed can be ramped from cut-in to cut-out with a fixed wind speed step. The steady state controller is used to determine the operating conditions at each speed.

• Idling: The blades are set to the idling pitch angle, and the rotor freedom is free. The analysis is conducted with both rotor speed and wind speed at zero.

• Parked: The rotor is fixed, and the blades are set to the parked pitch angle. Wind speeds can be varied, and both inclination and direction can be adjusted. If the option Tilt wind field according to hub axis is enabled, the ability to add inclination is disabled.

In cases where there are a lot of high frequency modes in the system (for example multi-part blades), high frequency modes can be excluded from the plot by setting the maximum frequency for plot. The rotating modes, such as blade modes can be transformed into the non-rotating frame using the multi-blade coordinate transform. This will generate forward and backward whirling modes in the output.

Last updated 26-11-2024