Optical Signal Aiming for Heliostats

Abstract

Methods and systems for managing heliostat aiming toward a target are described. Solar rays incident on a reflective surface of a heliostat mirror are reflected toward the target. One or more optical signalers are arranged at positions about the target. An optical signal received from one of the one or more optical signalers is detected. An error in an orientation of the reflective surface is determined based on the optical signal.

1 . A method for managing heliostat aiming toward a target, comprising:
 reflecting solar rays incident on a reflective surface of a heliostat mirror toward a target, wherein one or more optical signalers are arranged at positions about the target;   detecting an optical signal received from one of the one or more optical signalers; and   determining an error in an orientation of the reflective surface based on the optical signal.   
     
     
         2 . The method of  claim 1 , further comprising:
 adjusting the orientation of the reflective surface in response to determining the error.   
     
     
         3 . The method of  claim 2 , wherein adjusting the orientation comprises adjusting at least one of the azimuth or elevation of the reflective surface. 
     
     
         4 . The method of  claim 2 , wherein adjusting the orientation comprises adjusting the orientation along an axis other than along an azimuthal or elevational axis of the reflective surface. 
     
     
         5 . The method of  claim 1 , wherein one or more optical signalers comprise a plurality of optical signalers and determining an error in an orientation includes determining which optical signaler of the plurality of optical signalers transmitted the optical signal. 
     
     
         6 . The method of  claim 1 , wherein the one or more optical signalers comprise a plurality of retroreflectors positioned about the target. 
     
     
         7 . The method of  claim 6 , wherein:
 the optical signal is received from a particular one of the plurality of retroreflectors; and   determining the error in the orientation comprises:
 determining a frequency of a change in light that comprises the optical signal; and 
 based on the frequency, determining that the optical signal was received from the particular one of the plurality of retroreflectors; and 
 based on determining that the optical signal was received from the particular retroreflector, determining the error in orientation. 
   
     
     
         8 . The method of  claim 6 , wherein:
 the optical signal is received from a particular one of the plurality of retroreflectors; and   determining the error in the orientation comprises:
 determining a color of light that comprises the optical signal; and 
 based on the color, determining that the optical signal was received from the particular one of the plurality of retroreflectors; and 
 based on determining that the optical signal was received from the particular retroreflector, determining the error in orientation. 
   
     
     
         9 . The method of  claim 6 , wherein:
 the optical signal is received from a particular one of the plurality of retroreflectors; and   determining the error in the orientation comprises:
 determining a polarization of light that comprises the optical signal; and 
 based on the polarization, determining that the optical signal was received from the particular one of the plurality of retroreflectors; and 
 based on determining that the optical signal was received from the particular retroreflector, determining the error in orientation. 
   
     
     
         10 . The method of  claim 6 , wherein:
 the optical signal is received from a particular one of the plurality of retroreflectors; and   determining the error in the orientation comprises:
 determining a phasing of light that comprises the optical signal; and 
 based on the phasing, determining that the optical signal was received from the particular one of the plurality of retroreflectors; and 
 based on the determining that the optical signal was received from the particular retroreflector, determining the error in orientation. 
   
     
     
         11 . The method of  claim 1 , wherein determining an error in an orientation of the reflective surface based on the optical signal includes determining that the optical signal exceeds a threshold signal strength. 
     
     
         12 . The method of  claim 1 , wherein two optical signals are received from two optical signalers and determining an error in an orientation of the reflective surface based on the two optical signals includes determining that a difference in signal strength between the two optical signals exceeds a threshold difference. 
     
     
         13 . The method of  claim 1 , wherein the target comprises a receiver configured to receive solar rays. 
     
     
         14 . The method of  claim 1 , wherein the target comprises a location that is a distance away from a receiver that is configured to receive solar rays, such that solar rays from the heliostat mirror are not reflected to the receiver. 
     
     
         15 . A system comprising:
 a receiver assembly including:
 a receiver mounted on a receiver tower; 
 the receiver tower comprising a support structure configured to support the receiver; 
 an aperture included in the receiver and configured to receive solar rays reflected from a plurality of heliostats; 
 one or more signalers positioned at one or more distances from the aperture and configured to:
 receive solar rays reflected from at least one of the plurality of heliostats; and 
 in response to transmit an optical signal toward the at least one heliostat. 
 
   
     
     
         16 . The system of  claim 15 , wherein the one or more signalers comprise one or more retroreflectors mounted at one or more positions proximate to a circumference of the aperture. 
     
     
         17 . The system of  claim 15 , wherein the one or more signalers comprise a plurality of signalers and each signaler is configured to transmit an optical signal that is different than an optical signal transmitted by each of the other signalers in the plurality of signalers. 
     
     
         18 . The system of  claim 17 , wherein each signaler comprises a retroreflector that is configured to transmit an optical signal that has a different frequency of change in signal than optical signals transmitted by the other signalers in the plurality of signalers. 
     
     
         19 . The system of  claim 17 , wherein each signaler comprises a retroreflector that is configured to transmit an optical signal that has a different color than optical signals transmitted by the other signalers in the plurality of signalers. 
     
     
         20 . The system of  claim 17 , wherein each signaler comprises a retroreflector that is configured to transmit an optical signal that has a different polarization than optical signals transmitted by the other signalers in the plurality of signalers. 
     
     
         21 . The system of  claim 17 , wherein each signaler comprises a retroreflector that is configured to transmit an optical signal that has a different phasing than optical signals transmitted by the other signalers in the plurality of signalers. 
     
     
         22 . The system of  claim 15 , further comprising:
 the plurality of heliostats, wherein each heliostat includes:
 a reflective surface configured to reflect solar rays incident on the surface toward the receiver; 
 a sensor configured to receive optical signals from the one or more signalers; 
 an actuator configured to adjust an orientation of the reflective surface; 
 a controller configured to:
 determine errors in orientation of the reflective surface based on the optical signals received by the sensor; and 
 provide signals to the actuator to adjust the orientation of the reflective surface in response to the determined errors. 
 
   
     
     
         23 . The system of  claim 22 , wherein:
 the one or more signalers comprise a plurality of signalers, and each signaler is configured to transmit an optical signal that is different than an optical signal transmitted by the other signalers in the plurality of signalers; and   the controller is further configured to determine which particular signaler from the plurality of signalers transmitted a particular optical signal based on the difference in optical signals transmitted by the plurality of signalers.   
     
     
         24 . The system of  claim 22 , wherein the controller configured to determine errors in orientation of the reflective surface is further configured to determine that the optical signals exceed a threshold signal strength. 
     
     
         25 . The system of  claim 22 , wherein the controller configured to determine errors in orientation of the reflective surface is further configured to determine whether a difference between signal strengths of two optical signals received from two optical signalers exceeds a threshold difference and determine an error in orientation based on the determination.