Wind turbine control having a lidar wind speed measurement apparatus
A wind turbine is provided having a lidar wind speed measurement apparatus for achieving wind control. The lidar apparatus is arranged to scan the area in front of the wind turbine so as to generate a measurement of the wind speed across the wind field. The lidar apparatus may be located in the hub of the wind turbine and the look direction inclined away from the rotational axis so that rotation of the hub ensures scanning. Preferably the lidar apparatus has a plurality of look directions so as to increase the scanning rate. This may be achieved by having a number of dedicated lidar systems and/or by using multiplexed lidars. Measurement of the wind field allows improved control of the wind turbine giving efficiency and reduced wear benefits.
1. A wind turbine having a lidar means for determining wind speed wherein the lidar means is mounted in the hub of the turbine and has at least one look direction inclined to the axis of rotation thereof such that as the hub rotates the lidar means scans the area in front of the turbine, said lidar means comprising a multiplexed lidar, said multiplexed lidar comprising:
at least one laser source; and
a plurality of sets of transmit/receive optics, each set of transmit/receive optics having a different look direction.
2. A wind turbine as claimed in claim 1 wherein at least one look direction is inclined at an angle within the range of 5°-20° of the axis of rotation.
3. A wind turbine as claimed in claim 2 wherein at least one look direction is inclined at an angle within the range of 10°-20° of the axis of rotation.
4. A wind turbine as claimed in claim 1 further comprising a control means, responsive to the output of the lidar means, for controlling the pitch of the rotor blades.
5. A wind turbine as claimed in claim 4 wherein the control means is adapted to feather the rotor blades when incoming wind gusts are detected.
6. A wind turbine as claimed in claim 4 wherein the control means is adapted to independently alter the pitch of each blade as it rotates.
7. A wind turbine as claimed in claim 6 wherein the control means is adapted to alter the pitch of each blade to maximise energy extraction.
8. A wind turbine as claimed in claim 6 wherein the control means is adapted to alter the pitch of each blade to provide load balancing.
9. A wind turbine having a lidar for determining wind speed wherein the lidar is mounted in the rotating hub of the turbine, said lidar comprising a multiplexed lidar comprising:
at least one laser source; and
a plurality of sets of transmit/receive optics, each set of transmit/receive optics having a different look direction wherein as the hub rotates the lidar scans the area in front of the turbine.
10. A wind turbine as claimed in claim 9 wherein said different look directions are accomplished simultaneously.
11. A wind turbine as claimed in claim 9 wherein there are three different look directions.
12. A wind turbine as claimed in claim 9 wherein at least one look direction is inclined at an angle within the range of 5°-20° of the axis of rotation.
13. A wind turbine as claimed in claim 12 wherein at least one look direction is inclined at an angle within the range of 10°-20° of the axis of rotation.
14. A wind turbine as claimed in claim 9 further comprising a control means, responsive to an output of the lidar, for controlling the pitch of the rotor blades.
15. A wind turbine as claimed in claim 14 wherein the control means is adapted to feather the rotor blades when incoming wind gusts are detected.
16. A wind turbine as claimed in claim 14 wherein the control means is adapted to independently alter the pitch of each blade as it rotates.
17. A wind turbine as claimed in claim 16 wherein the control means is adapted to alter the pitch of each blade to maximise energy extraction.
18. A wind turbine as claimed in claim 16 wherein the control means is adapted to alter the pitch of each blade to provide load balancing.
19. A wind turbine as claimed in claim 9 further comprising a controller, responsive to an output of the lidar, for controlling the pitch of the rotor blades.
20. A wind turbine as claimed in claim 19 wherein the controller is adapted to feather the rotor blades when incoming wind gusts are detected.
21. A wind turbine as claimed in claim 19 wherein the controller is adapted to independently alter the pitch of each blade as it rotates.
22. A wind turbine as claimed in claim 21 wherein the controller is adapted to alter the pitch of each blade to maximise energy extraction.
23. A wind turbine as claimed in claim 21 wherein the controller is adapted to alter the pitch of each blade to provide load balancing.