Method and system for monitoring an individual blade adjustment of a wind turbine
The invention relates to a method and a system for monitoring an individual blade adjustment of a wind turbine which includes a tower, a rotor which is arranged on the tower and has at least two rotor blades whose blade angle can be adjusted individually, and a blade adjustment system, wherein the blade adjustment system includes a blade controller and sensors for sensing individual actual blade angles of the at least two rotor blades, wherein an individual blade controller is included which receives a collective set point blade angle from the blade controller and which actuates at least two rotor blades with respectively individual set point blade angles, as well as a corresponding wind turbine.
1. A method for operating a wind turbine that includes
a tower,
a rotor arranged on the tower having at least two rotor blades, wherein of each of said at least two rotor blades has an individually adjustable blade angle,
a blade adjustment system that includes a blade controller and sensors for sensing individual actual blade angles θ i act of the at least two rotor blades, and
an individual blade controller configured to receive a collective set point blade angle θ c set from the blade controller and to actuate the at least two rotor blades with individual set point blade angles θ i IPC , respectively,
the method comprising:
forming a difference signal based upon a difference between
(a) a collective blade angle actual mean value θ act and a collective blade angle set point mean value θ IPC ;
(b) the collective set point mean value θ IPC and the collective set point blade angle θ c set ; or
(c) the collective set point blade angle θ c set and a collective actual mean value θ act ;
averaging the difference signal over time to obtain an averaged over time value;
monitoring the averaged over time value to determine whether at least one limiting value is exceeded in absolute terms; and
reducing an operation of the wind turbine with respect to load when the averaged over time value exceeds the at least one limiting value in absolute terms and determining a malfunction of:
(i) a blade adjustment drive or a blade bearing where the difference signal is based upon the difference between (a) the collective blade angle actual mean value θ act and the collective blade angle set point mean value θ IPC ; or
(ii) the individual blade controller where the difference signal is based upon the difference between either (b) the collective set point mean value θ IPC and the collective set point blade angle θ c set or (c) the collective set point blade angle θ c set and the collective actual mean value θ act .
2. The method according to claim 1 , wherein in order to calculate the set point mean value θ IPC , averaging is carried out over the individual set point blade angles θ i IPC of the individual blade controller or a response of the blade adjustment system to the requested individual set point blade angles θ i IPC is simulated, and averaging is carried out over the simulated individual blade angles θ i sim of the simulated blade adjustment system.
3. The method according to claim 1 , wherein in order to calculate the set point mean value θ IPC , averaging is carried out over the individual set point blade angles θ i IPC of the individual blade controller and a response of the blade adjustment system to the requested individual set point blade angles θ i IPC is simulated, and averaging is carried out over the simulated individual blade angles θ i sim of the simulated blade adjustment system.
4. The method according to claim 1 , wherein the averaging over time is carried out over an averaging duration which is less than a duration of half a rotor revolution.
5. The method according to claim 4 , wherein the duration is between 0.5 seconds and 2 seconds.
6. A system for operating a wind turbine that includes
a tower,
a rotor arranged on the tower having at least two rotor blades, wherein of each of said at least two rotor blades has an individually adjustable blade angle,
a blade adjustment system that includes a blade controller and sensors for sensing individual actual blade angles θ i act of the at least two rotor blades, and
an individual blade controller configured to receive a collective set point blade angle θ c set from the blade controller and to actuate the at least two rotor blades with individual set point blade angles θ i IPC , respectively,
said system comprising a monitoring device configured to:
form a difference signal based upon a difference between
(a) a collective blade angle actual mean value θ act and a collective blade angle set point mean value θ IPC ;
(b) the collective set point mean value θ IPC and the collective set point blade angle θ c set ; or
(c) the collective set point blade angle θ c set and a collective actual mean value θ act ;
average the difference signal over time to obtain an averaged over time value;
monitor the averaged over time value to determine whether at least one limiting value is exceeded in absolute terms; and
reduce an operation of the wind turbine with respect to load when the averaged over time value exceeds the at least one limiting value in absolute terms and determine a malfunction of:
(i) a blade adjustment drive or a blade bearing where the difference signal is based upon the difference between (a) the collective blade angle actual mean value θ act and the collective blade angle set point mean value θ IPC ; or
(ii) the individual blade controller where the difference signal is based upon the difference between either (b) the collective set point mean value θ IPC and the collective set point blade angle θ c set or (c) the collective set point blade angle θ c set and the collective actual mean value θ act .
7. The system according to claim 6 , wherein the monitoring device is integrated into an operational control system or into the blade adjustment system of the wind turbine.
8. A wind turbine comprising:
a tower;
a rotor arranged on the tower having at least two rotor blades, wherein of each of said at least two rotor blades has an individually adjustable blade angle;
a blade adjustment system that includes a blade controller and sensors for sensing individual actual blade angles θ i act of the at least two rotor blades;
an individual blade controller configured to receive a collective set point blade angle θ c set from the blade controller and to actuate the at least two rotor blades with individual set point blade angles θ i IPC , respectively; and
a system for operating a wind turbine according to claim 6 .
9. A system for monitoring an individual blade adjustment of a wind turbine that includes
a tower,
a rotor arranged on the tower having at least two rotor blades, wherein of each of said at least two rotor blades has an individually adjustable blade angle,
a blade adjustment system that includes a blade controller and sensors for sensing individual actual blade angles θ i act of the at least two rotor blades, and
an individual blade controller configured to receive a collective set point blade angle θ c set from the blade controller and to actuate the at least two rotor blades with individual set point blade angles θ i IPC , respectively,
wherein the system comprises:
a monitoring device configured to:
form a difference signal based upon a difference between
(a) a collective blade angle actual mean value θ act and a collective blade angle set point mean value θ IPC ;
(b) the collective set point mean value θ IPC and the collective set point blade angle θ c set ; or
(c) the collective set point blade angle θ c set and a collective actual mean value θ act ;
average the difference signal over time to obtain an averaged over time value; and
monitor the averaged over time value to determine whether at least one limiting value is exceeded in absolute terms; and
means configured to carry out a method according to claim 1 .