Method for operating a variable-speed wind turbine and the wind turbine
A method for operating a wind turbine with a variable speed rotor, a control system and a safety system, including the steps of initiating a braking procedure of the rotor of the wind turbine by the control system when the rotational speed of the rotor exceeds a first threshold value (n c1 ), and activating a safety system for braking the rotor when the rotational speed of the rotor exceeds a second threshold value (n s1 ) and when the control system has not initiated a braking procedure, the second threshold value (n s1 ) being greater than the first threshold value (n c1 ).
1. A method for operating a wind turbine with a variable-speed rotor, a control system and a safety system, comprising the steps of:
activating the safety system for braking the rotor when a rotational speed of the rotor exceeds either a second threshold value (n s1 ) or a third threshold value (n s2 ), the second threshold value (n s1 ) being less than the third threshold value (n s2 ),
wherein when the rotational speed of the rotor exceeds the second threshold value (n s1 ), the safety system is activated only if the control system has not initiated a control system braking procedure in response to the rotational speed of the rotor being greater than a first threshold value (n c1 ) that is less than the second threshold value (n s1 ); and
wherein when the rotational speed of the rotor exceeds the third threshold value (n s2 ), the safety system is activated even if the control system has initiated the control system braking procedure in response to the rotational speed of the rotor being greater than the first threshold value (n c1 ).
2. The method according to claim 1 , wherein the control system and the safety system trigger the blade pitch control system of at least one rotor blade for braking the rotor.
3. The method according to claim 1 , wherein the control system reduces the rotational speed of the rotor for braking.
4. The method according to claim 1 , wherein the safety system reduces the rotational speed of the rotor for braking.
5. The method according to claim 1 , wherein after activation of the safety system, the wind turbine has to be checked for any damages occurred and the safety system has to be enabled before starting the operation of the wind turbine again.
6. A method for operating a wind turbine, the wind turbine comprising a rotor characterized by a rotational speed; a control system configured and arranged to compare the rotational speed to a first threshold value (n c1 ), and to initiate a control system braking procedure of the rotor; and a safety system configured and arranged to compare the rotational speed to a second threshold value (n s1 ) and to a third threshold value (n s2 ), the second threshold value (n s1 ) being greater than the first threshold value (n c1 ) and less than the third threshold value (n s2 ), and configured and arranged to initiate a safety system braking procedure of the rotor; the method comprising:
comparing the rotational speed to the second threshold value (n s1 ), wherein if the rotational speed is greater than the second threshold value (n s1 ), the safety system checks whether the control system braking procedure was initiated in response to the rotational speed exceeding the first threshold value (n c1 ), and then initiates the safety system braking procedure only if the control system braking procedure was not initiated.
7. The method of claim 6 , wherein if the safety system did not initiate the safety system braking procedure in response to the rotational speed exceeding the second threshold value (n s1 ), the method further comprises:
comparing the rotational speed to the third threshold value (n s2 ), wherein if the rotational speed exceeds the third threshold value (n s2 ) the safety system initiates the safety system braking procedure.
8. The method of claim 6 , wherein the safety system has logical priority over the control system.
9. The method of claim 6 , wherein the first threshold value (n c1 ) is a maximum rotational speed for the wind turbine.
10. A method for operating a wind turbine with a rotor, a control system and a safety system configured to initiate a safety system braking procedure, the method comprising the steps of:
prompting the control system to initiate a control system braking procedure when a rotational speed of the rotor exceeds a first threshold value (n c1 ), and
activating the safety system when the rotational speed of the rotor exceeds a second threshold value (n s1 ) wherein activating the safety system when the rotational speed of the rotor exceeds the second threshold value (n s1 ) includes checking whether the control system braking procedure was initiated, and initiating the safety system braking procedure only if the control system braking procedure was not initiated.
11. The method according to claim 10 , further comprising activating the safety system when the rotational speed of the rotor exceeds a third threshold value (n s2 ) greater than the second threshold value (n s1 ), wherein activating the safety system when the rotational speed of the rotor exceeds the third threshold value (n s2 ) comprises initiating the safety system braking procedure even if the control system braking procedure was initiated.
12. The method according to claim 10 , wherein the control system and the safety system trigger a blade pitch control system of at least one rotor blade for braking the rotor.
13. The method according to claim 10 , wherein the control system reduces the rotational speed of the rotor for braking.
14. The method according to claim 10 , wherein the safety system reduces the rotational speed of the rotor up to the standstill of the rotor for braking.
15. The method according to claim 10 , wherein after an activation of the safety system, the wind turbine has to be checked for any damages occurred and the safety system has to be enabled before starting the operation of the wind turbine again.