Method for operating a wind turbine and wind turbine

A computer program for operating a wind turbine including a rotor with a rotor blade and a setting system configured to change an operation of the wind turbine, the computer program comprising:

• instructions stored on a non-transitory computer readable medium;
• said instructions being configured, when the computer program is executed by a computer, cause the computer to:
• provide first trigger information which is representative of whether a torsional vibration of the rotor blade exceeds a threshold;
• and,
• generate a first output signal when the torsional vibration of the rotor blade exceeds the threshold wherein the first output signal is configured to cause the setting system to change the operation of the wind turbine in order to reduce the torsional vibration of the rotor blade
• wherein at least one of:
• said instructions are further configured, when the computer program is executed by the computer, to cause the computer to provide second base information which is representative of a torsional bending moment acting on the rotor blade;
• wherein the first trigger information is determined in dependence upon the second base information;
• wherein the determining of the first trigger information includes applying at least one filter to the second base information in order to extract an oscillation of the torsional bending moment of the rotor blade with a torsional eigenfrequency, and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• said instructions are further configured, when the computer program is executed by the computer, to cause the computer to provide at least one of third base information and fourth base information which are respectively representative of at least one of an edgewise bending moment and a flapwise bending moment acting on the rotor blade, wherein the first trigger information is determined in dependence upon at least one of the third and the fourth information, wherein the determining of the first trigger information includes applying at least one filter to at least one of the third base information and the fourth base information in order to extract an oscillation of at least one of the edgewise bending moment and the flapwise bending moment of the rotor blade with a torsional eigenfrequency of the rotor blade;
• and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• said instructions are further configured, when the computer program is executed by the computer, to cause the computer to provide a fifth base information which is representative of an angular acceleration of the rotor blade, wherein the first trigger information is determined depending on the fifth base information, wherein the fifth base information is determined in dependence upon measurements taken with the help of a fifth sensor system, wherein the fifth sensor system includes at least one acceleration sensor for measuring an angular acceleration of the rotor blade;
• said determining of the first trigger information includes applying at least one filter to the fifth base information in order to extract an oscillation of the angular acceleration of the rotor blade with a torsional eigenfrequency;
• and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• and,
• the setting system is configured to execute at least two different measures for reducing the torsional vibration of the rotor blade;
• the first output signal is configured to cause the setting system to execute a first measure for reducing the torsional vibration of the rotor blade;
• the method further comprises providing a second trigger information which is representative of whether the torsional vibration of the rotor blade exceeds the threshold after the first measure has been executed;
• and, generating, if the torsional vibration exceeds the threshold, a second output signal configured to cause the setting system to execute a second measure for reducing the torsional vibration of the rotor blade, wherein each of the first measure and the second measure is one of:
• changing the pitch angle of the rotor blade, changing the speed of rotation of the rotor without stopping the rotation of the rotor, changing the electrical power output of the wind turbine, and shutting down the wind turbine, wherein the first measure and the second measure differ from each other.

A control system for operating a wind turbine having a rotor with a rotor blade and a setting system for changing an operation of the wind turbine, the control system comprising:

• at least one sensor system configured to take measurements with help of which it is determinable whether a torsional vibration of the rotor blade exceeds a threshold;
• a control device including a processor and a non-transitory computer-readable storage medium having program code stored thereon;
• said program code being configured, when executed by said processor, to provide first trigger information which is representative of whether the torsional vibration of the rotor blade exceeds the threshold, and generate a first output signal when the torsional vibration of the rotor blade exceeds the threshold wherein said first output signal is configured to cause the setting system to change the operation of the wind turbine in order to reduce the torsional vibration of the rotor blade;
• said control device being signally connectable to said at least one sensor system in order to provide said control device with the measurements of said at least one sensor system;
• and,
• said control device being signally connectable to the setting system in order to provide the setting system with said first output signal of said control device so that the setting system changes the operation of the wind turbine in dependence upon said first output signal
• wherein at least one of:
• said program code is further configured, when the computer program is executed by the computer, to cause the computer to provide second base information which is representative of a torsional bending moment acting on the rotor blade;
• wherein the first trigger information is determined in dependence upon the second base information;
• wherein the determining of the first trigger information includes applying at least one filter to the second base information in order to extract an oscillation of the torsional bending moment of the rotor blade with a torsional eigenfrequency, and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• said program code is further configured, when the computer program is executed by the computer, to cause the computer to provide at least one of third base information and fourth base information which are respectively representative of at least one of an edgewise bending moment and a flapwise bending moment acting on the rotor blade, wherein the first trigger information is determined in dependence upon at least one of the third and the fourth information, wherein the determining of the first trigger information includes applying at least one filter to at least one of the third base information and the fourth base information in order to extract an oscillation of at least one of the edgewise bending moment and the flapwise bending moment of the rotor blade with a torsional eigenfrequency of the rotor blade;
• and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• said program code is further configured, when the computer program is executed by the computer, to cause the computer to provide a fifth base information which is representative of an angular acceleration of the rotor blade, wherein the first trigger information is determined depending on the fifth base information, wherein the fifth base information is determined in dependence upon measurements taken with the help of a fifth sensor system, wherein the fifth sensor system includes at least one acceleration sensor for measuring an angular acceleration of the rotor blade;
• said determining of the first trigger information includes applying at least one filter to the fifth base information in order to extract an oscillation of the angular acceleration of the rotor blade with a torsional eigenfrequency;
• and, determining whether an amplitude of the oscillation with the torsional eigenfrequency exceeds a threshold;
• and,
• the setting system is configured to execute at least two different measures for reducing the torsional vibration of the rotor blade;
• the first output signal is configured to cause the setting system to execute a first measure for reducing the torsional vibration of the rotor blade;
• the method further comprises providing a second trigger information which is representative of whether the torsional vibration of the rotor blade exceeds the threshold after the first measure has been executed;
• and, generating, if the torsional vibration exceeds the threshold, a second output signal configured to cause the setting system to execute a second measure for reducing the torsional vibration of the rotor blade, wherein each of the first measure and the second measure is one of:
• changing the pitch angle of the rotor blade, changing the speed of rotation of the rotor without stopping the rotation of the rotor, changing the electrical power output of the wind turbine, and shutting down the wind turbine, wherein the first measure and the second measure differ from each other.