Method and system for determining a mass change at a rotating blade of a wind turbine
View Patent ↗A method for determining a mass change at a rotating blade of a wind turbine is provided. The method includes measuring a vibration quantity representative of a vibration of the wind turbine, measuring an azimuthal quantity representative of a rotation angle of the blade, determining a frequency quantity representative of a vibration frequency of the blade from the vibration quantity and the azimuthal quantity, and determining the mass change at the blade based on the frequency quantity.
1. A method for determining a mass change at a rotating blade of a wind turbine, the method comprising:
measuring a vibration quantity representative of a vibration of the wind turbine;
measuring an azimuthal quantity representative of a rotation angle of the blade;
determining a frequency quantity representative of a vibration frequency of the blade from the vibration quantity and the azimuthal quantity; and
determining the mass change at the blade based on the frequency quantity,
wherein the determining the mass change comprises comparing the frequency quantity with a predetermined reference frequency, and
wherein the determining the frequency quantity comprises multiplying a trigonometric function of a term related to the azimuthal quantity with the vibration quantity.
2. The method according to claim 1 , wherein the determining the frequency quantity is further based on a temperature of the wind turbine.
3. The method according to claim 2 , wherein the frequency quantity is linearly dependent on the temperature of the wind turbine.
4. The method according to claim 1 , wherein the determining the mass change comprises comparing the frequency quantity with a predetermined reference frequency or a temperature dependent reference frequency.
5. The method according to claim 1 , wherein the measuring the vibration quantity comprises measuring the vibration quantity using an accelerometer, arranged at a nacelle of the wind turbine.
6. The method according to claim 1 , wherein the measuring the vibration quantity comprises measuring the vibration quantity in at least one direction in a rotation plane of the blade.
7. The method according to claim 1 , wherein the determining the frequency quantity comprises performing a frequency analysis of the vibration quantity.
8. The method according to claim 1 , further comprising indicating an icing at the blade when the mass change is determined.
9. The method according to claim 8 , wherein the indicating the icing is further based on a measured meteorological quantity.
10. The method according to claim 9 , wherein the meteorological quantity is a temperature and/or a humidity.
11. A method for operating a wind turbine, the method comprising:
rotating a blade according to a first operation mode;
determining a mass change at the rotating blade according to the method according to claim 1 ; and
changing the operation mode to a second operation mode, when the mass change has been determined.
12. The method according to claim 11 , wherein the second operation mode comprises operating a deicing system for deicing the rotor blade.
13. The method according to claim 11 , wherein the second operation mode comprises stopping the rotating the blade.
14. A method for determining a mass change at a rotating blade of a wind turbine, the method comprising:
measuring a vibration quantity representative of a vibration of the wind turbine;
measuring an azimuthal quantity representative of a rotation angle of the blade;
determining a frequency quantity representative of a vibration frequency of the blade from the vibration quantity and the azimuthal quantity; and
determining the mass change at the blade based on the frequency quantity,
wherein the determining the mass change comprises comparing the frequency quantity with a predetermined reference frequency or a temperature dependent reference frequency,
wherein the mass change is determined when the frequency quantity deviates from the reference frequency by a predetermined threshold which depends on a stiffness and/or a weight of the blade, and
wherein the predetermined threshold is between 10 mHz and 100 mHz.
15. The method according to claim 14 , wherein when the frequency quantity is smaller than the predetermined reference frequency by at least the predetermined threshold, the mass change is a mass increase.
16. A method for determining a mass change at a rotating blade of a wind turbine, the method comprising:
measuring a vibration quantity representative of a vibration of the wind turbine;
measuring an azimuthal quantity representative of a rotation angle of the blade;
determining a frequency quantity representative of a vibration frequency of the blade from the vibration quantity and the azimuthal quantity; and
determining the mass change at the blade based on the frequency quantity,
wherein the determining the frequency quantity comprises multiplying a trigonometric function of a term related to the azimuthal quantity with the vibration quantity.