Method for condition monitoring a rotor of a wind energy plant
A method for condition monitoring a rotor of a wind energy plant includes the steps of measuring activity signals of the blades in the rotor and establishing one or more differential values between the activity signals of different blades. The one or more differential values are used for monitoring the condition of the rotor in the wind energy plant. A wind energy plant, a cluster of wind energy plants and use hereof is also contemplated.
1. A method for monitoring a health condition of a rotor of a wind energy plant, said method comprising the steps of:
measuring activity signals of blades in said rotor,
establishing differential values between the activity signals of different blades, and
wherein the differential values are used for monitoring the health condition of the rotor in the wind energy plant.
2. The method according to claim 1 , wherein the activity signals are measured with acoustic sensors in contact with structural means of the rotor.
3. The method according to claim 2 , where said structural means of the rotor comprises one or more rotor blade pitch bearings.
4. The method according to claim 1 , where said monitoring is performed continuously, with predefined intervals and/or initiated in response to a detected abnormal situation.
5. The method according to claim 4 , where the abnormal situation is detected in at least one physical work property of at least one component of said wind energy plant.
6. The method according to claim 1 , where the activity signals are averaged or integrated over a time period before differential values are established.
7. The method according to claim 1 , where the activity signals are time delayed before differential values are established.
8. The method according to claim 1 , where said differential values are compared with a predefined value in order to establish whether the blades have similar activity signals or not.
9. The method according to claim 8 , where a number of acoustic sensors measures a condition of a blade when a differential value is above the predefined value for said blade.
10. The method according to claim 1 , where comparison between all differential values are performed.
11. A method for controlling a rotor of a wind energy plant on the basis of a health condition of the rotor, said method comprising the steps of:
measuring activity signals of blades in said rotor, and
establishing one or more differential values between the activity signals of different blades,
wherein said one or more differential values are used for controlling at least one of loads on rotor blades and loads on pitch bearings of the rotor in the wind energy plant.
12. A wind energy plant comprising
a wind energy plant rotor including at least two blades,
one or more acoustic sensors positioned in contact with strengthening structure of the blades for measuring activity signals of said blades, and
means for establishing one or more differential values by comparison between said activity signals,
wherein said wind energy plant further comprises means for controlling the rotor of the wind energy plant on the basis of said established differential values.
13. The wind energy plant according to claim 12 wherein one or more acoustic sensors are positioned in each blade of the wind energy plant rotor.
14. The wind energy plant according to claim 12 wherein one or more acoustic sensors are positioned in a hub of the wind energy plant rotor.
15. The wind energy plant according to claim 12 wherein each blade comprises a plurality of acoustic sensors.
16. The wind energy plant according to claim 12 wherein each blade comprises rows of connected acoustic sensors.
17. The wind energy plant according to claim 16 , wherein a row substantially extends from a blade root to a blade tip.
18. The wind energy plant according to claim 16 wherein a row is distributed in a region of a trailing and leading edge and a suction and pressure side, respectively.
19. The wind energy plant according to claim 12 wherein said means for controlling is part of a wind energy plant control system.
20. The wind energy plant according to claim 19 wherein said wind energy plant control system individually pitches the blades in response to said differential values between the blades.
21. The wind energy plant according to claim 12 wherein said plant comprises means for comparison between all differential values.
22. A cluster of wind energy plants comprising at least two wind energy plants according to claim 12 .
23. The cluster of wind energy plants according to claim 22 wherein the wind energy plants are controlled by a distributed control system.