Method for controlling the alignment of a heliostat with respect to a receiver, heliostat device and solar power plant

• US 20090249787A1
• Filed: 04/06/2009
• Published: 10/08/2009
• Est. Priority Date: 11/13/2006
• Status: Active Grant

• Current Assignee: Deutsches Zentrum Fã¼R Luft- Und Raumfahrt E.V.
• Original Assignee: Deutsches Zentrum Fã¼R Luft- Und Raumfahrt E.V.
• Inventors: Buck, Reiner, Pfahl, Andreas, Rehschuh, Karsten
• Granted Patent: US 8,651,100 B2
• Time in Patent Office: Days
• US Class Current: 60/641.110
• CPC Class Codes: F24S 20/20 Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
• CPC Class Codes: F24S 30/452 Vertical primary axis
• CPC Class Codes: F24S 50/20 for tracking
• CPC Class Codes: G01S 3/781 Details
• CPC Class Codes: G01S 3/7861 Solar tracking systems
• CPC Class Codes: G06V 10/147 Details of sensors, e.g. sensor lenses fingerprint or palmprint sensors G06V40/13; vascular sensors G06V40/145; eye sensors G06V40/19
• CPC Class Codes: G06V 10/46 Descriptors for shape, contour or point-related descriptors, e.g. scale invariant feature transform [SIFT] or bags of words [BoW]; Salient regional features colour feature extraction G06V10/56
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/46 Conversion of thermal power into mechanical power, e.g. Rankine, Stirling or solar thermal engines
• CPC Class Codes: Y02E 10/47 Mountings or tracking

Abstract

A method is provided for controlling the alignment of a heliostat with respect to a receiver, wherein an image sensor device is arranged on a mirror device of the heliostat, wherein the heliostat is aligned by the image sensor device using image recognition in such a way that a first angle of a first vector pointing towards the sun, relative to a prescribed vector of the mirror device, and a second angle of a second vector pointing towards a prescribed target area of the receiver, relative to the prescribed vector, are in a relationship to each other which is dependent upon the prescribed vector of the mirror device, and wherein images of the sun and the prescribed target area and their position relative to the prescribed vector are determined.

Claims

1. Method for automatically controlling the alignment of a heliostat with respect to a receiver;

wherein a two-dimensional image sensor device is arranged on a mirror device of the heliostat;

comprising;

aligning the heliostat by the image sensor device using image recognition on a two-dimensional image in such a way that a first angle of a first vector pointing towards the sun, relative to a prescribed vector of the mirror device, and a second angle of a second vector pointing towards a prescribed target area of the receiver, relative to the prescribed vector, are in a relationship to each other which is dependent upon the prescribed vector of the mirror device; and

determining images which are formed of the sun and the prescribed target area, and determining their position relative to the prescribed vector.

2. Method in accordance with claim 1, wherein the prescribed vector of the mirror device is a normal vector to a mirror surface.

3. Method in accordance with claim 2, wherein the heliostat is so aligned that the first angle and the second angle are substantially identical.

4. Method in accordance with claim 1, wherein the image sensor device is arranged on a mirror surface of the mirror device.

5. Method in accordance with claim 1, wherein the image sensor device is designed as a two-dimensional image sensor device.

6. Method in accordance with claim 1, wherein an optical imaging device is associated with the image sensor device.

7. Method in accordance with claim 6, wherein the optical imaging device has a spectrally selective characteristic.

8. Method in accordance with claim 6, wherein the optical imaging device comprises at least one aperture.

9. Method in accordance with claim 6, wherein the optical imaging device comprises a plurality of partial imaging devices for respectively imaging a partial angle area.

10. Method in accordance with claim 9, wherein a partial imaging device is designed so as to enable the image sensor device to recognize whether the partial imaging device is active or not.

11. Method in accordance with claim 1, wherein the image sensor device is arranged and designed such that the sun and the prescribed target area are imaged in all relevant operating points.

12. Method in accordance with claim 1, wherein the image sensor device is fixedly positioned in a central area of a mirror surface of the mirror device.

13. Method in accordance with claim 1, wherein one or more markings for the image recognition by the image sensor device are positioned on at least one of the receiver and a heliostat field.

14. Method in accordance with claim 13, wherein the marking or markings are formed using at least one of passive and active elements.

15. Method in accordance with claim 13, wherein the marking or markings is or are formed by a bright, at least partial border on the target area of the receiver.

16. Method in accordance with claim 13, wherein the marking or markings is or are formed by one or more active light-emitting elements.

17. Method in accordance with claim 1, wherein a first forming of an image for the sun and a second forming of an image for the receiver are performed with the image sensor device.

18. Method in accordance with claim 17, wherein the first forming of an image and the second forming of an image are performed with a time interval between these.

19. Method in accordance with claim 17, wherein the first forming of an image is performed with a shorter exposure time than the second forming of an image.

20. Method in accordance with claim 1, wherein a controlled variable is the position of the image of the sun and of the image of the target area of the receiver relative to the prescribed vector.

21. Method in accordance with claim 20, wherein a controlled variable is the position of a certain point on a connecting line between an image of the sun and an image of the target area of the receiver.

22. Method in accordance with claim 21, wherein the automatic control is carried out such that the certain point lies on a prescribed image curve or at a prescribed image point.

23. Method in accordance with claim 21, wherein the certain point is the midpoint of the connecting line.

24. Method in accordance with claim 23, wherein the automatic control is carried out such that the midpoint lies substantially at the same position in the image.

25. Method in accordance with claim 1, wherein an adjustment position for the mirror device is determined from a deviation of a controlled variable from a required value.

26. Method in accordance with claim 1, wherein at least one of the position of the sun and a required position for the mirror device is calculated by a non-automatic control mode.

27. Method in accordance with claim 26, wherein the images of the target area of the receiver are determined in the automatic control mode, and at least one of the calculated position of the sun and the calculated required position for the mirror device is used for the adjustment of the mirror device.

28. Method in accordance with claim 1, wherein at least one of the intensity and the contour of an image of the sun is measured in order to check whether the automatic control of the alignment of the mirror device is possible using the image of the sun.

29. Method in accordance with claim 1, wherein the coordinates of an image associated with the prescribed vector of the mirror device are determined by a calibration procedure.

30. Heliostat device, comprising:

a movable mirror device;

a two-dimensional image sensor device arranged on the mirror device;

an optical imaging device associated with the image sensor device; and

a control device including an image recognition device;

the mirror device being alignable by the image sensor device and the control device using image recognition of a two-dimensional image of the sun and an image of a target area of a receiver;

said control device being adapted to perform the steps;

aligning the heliostat by the image sensor device using image recognition on a two-dimensional image in such a way that a first angle of a first vector pointing towards the sun, relative to a prescribed vector of the mirror device, and a second angle of a second vector pointing towards a prescribed target area of the receiver, relative to the prescribed vector, are in a relationship to each other which is dependent upon the prescribed vector of the mirror device; and

determining images which are formed of the sun and the prescribed target area, and determining their position relative to the prescribed vector.

31. Heliostat device in accordance with claim 30, wherein the mirror device is rotatable about at least two axes.

32. Heliostat device in accordance with claim 30, comprising a drive device for moving the mirror device.

33. Heliostat device in accordance with claim 30, wherein the image sensor device is designed as a two-dimensional image sensor device.

34. Heliostat device in accordance with claim 33, wherein the image sensor device has a normal direction which is parallel to a normal direction of a mirror surface of the mirror device.

35. Heliostat device in accordance with claim 30, wherein an optical imaging device is associated with the image sensor device.

36. Heliostat device in accordance with claim 35, wherein the optical imaging device has a spectrally selective characteristic.

37. Heliostat device in accordance with claim 35, wherein the optical imaging device has at least one aperture.

38. Heliostat device in accordance with claim 35, wherein the optical imaging device has a plurality of partial imaging devices for respectively forming images of partial angle areas.

39. Heliostat device in accordance with claim 30, wherein the image sensor device is arranged and designed so as to enable images of the sun and the prescribed target area of the receiver to be formed in all relevant operating points.

40. Heliostat device in accordance with claim 39, wherein the image sensor device is fixedly positioned in a central area of a mirror surface of the mirror device.

41. Heliostat device in accordance with claim 30, wherein the control device includes an image recognition device.

42. Heliostat device in accordance with claim 30, wherein the control device includes a device for calculating at least one of the position of the sun and a required position for the mirror device.

43. Heliostat device in accordance with claim 30, wherein the control device includes a device for controlling an imaging time for the sun and the target area of the receiver.

44. Solar power plant, comprising:

at least one receiver; and

at least one heliostat device by means of which solar radiation is directable onto the at least one receiver;

wherein the at least one heliostat device comprises;

a movable mirror device;

a two-dimensional image sensor device arranged on the mirror device;

an optical imaging device associated with the image sensor device; and

a control device including an image recognition device;

wherein the mirror device is alignable by the image sensor device and the control device using image recognition of a two-dimensional image of the sun and an image of a target area of a receiver.

45. Solar power plant in accordance with claim 44, wherein at least one of the at least one receiver and a heliostat field comprises one or more markings for the image recognition by the image sensor device on the at least one heliostat device.

46. Solar power plant in accordance with claim 45, wherein the marking or markings is or are formed by a bright, at least partial border on a target area of the receiver.

47. Solar power plant in accordance with claim 44, wherein the at least one receiver has one or more markings for a calibration of the heliostat device.

48. Solar power plant in accordance with claim 44, wherein the at least one receiver is a tower receiver.