Devices, methods, and systems for control of heliostats

Abstract

Adherence to flux or resultant measurable parameter limits, ranges, or patterns can be achieved by directing heliostat mounted mirrors to focus on aiming points designated on the surface of a solar receiver. Different heliostats can be directed to different aiming points, and a heliostat can be directed to different aiming points at different times. The cumulative flux distribution resulting from directing a plurality of heliostats to any aiming point on a receiver surface can be predicted by using statistical methods to calculate the expected beam projection for each individual heliostat or alternatively for a group of heliostats. Control of the heliostats in a solar power system can include designating aiming points on a receiver from time to time and assigning heliostats to aiming points from time to time in accordance with an optimization goal.

1 . A heliostat control method implementable by a processor-based programmable controller connected to heliostats in a central tower solar thermal power generation system, solar thermal power generation system having a central receiver, the method controlling the heliostat aiming in real time and comprising:
 storing data representing shape error of each of a plurality of heliostats;   selecting, at multiple times during a day, a respective aiming point on the surface of the central receiver for each of said plurality of heliostats and generating control signals to aim said each of said plurality of heliostats responsively to said selecting;   said selecting being responsive to said data, where the focus error is such that a flux distribution on said central receiver generated by said each of said plurality of heliostats varies with apparent angle of the sun and with possible aiming points from which said aiming points is selected;   generating command signals effective to change said respective aiming point.   
     
     
         2 . The method of  claim 1 , wherein the selecting is responsive to a predefined constraint on the total flux received at said central receiver surface. 
     
     
         3 . The method of  claim 2 , wherein the constraint varies over time. 
     
     
         4 . The method of  claim 2 , wherein the constraint is determined to compensate for aging of the receiver. 
     
     
         5 . The method of  claim 2 , wherein the constraint is determined to compensate for changes in the reflectivity of the receiver. 
     
     
         6 . The method of  claim 2 , wherein the constraint is responsive to the temperature of the receiver. 
     
     
         7 . The method of  claim 2 , wherein the constraint is responsive to conditions that affect the temperature of the receiver. 
     
     
         8 . The method of  claim 7 , wherein the conditions that affect the temperature of the receiver include wind speed, relatively humidity, flow in the central receiver, flow per loop in the central receiver. 
     
     
         9 . The method of  claim 1 , further comprising generating data representing shape error of each of a plurality of heliostats responsively to measurements of said each of a plurality of heliostats. 
     
     
         10 . The method of  claim 1 , wherein the plurality of heliostats is a subset of all the heliostats in said central tower solar thermal power system. 
     
     
         11 . The method of  claim 1 , wherein the selecting is performed at a plurality of times responsive to a time of year. 
     
     
         12 . The method of  claim 1 , wherein the selecting is performed at a plurality of times responsive to a weather condition. 
     
     
         13 . The method of  claim 1 , wherein the selecting is performed at a plurality of times responsive to a performance condition of said each of said plurality of heliostats. 
     
     
         14 . The method of  claim 1 , wherein the data representing shape error includes a characteristic of the shape of a heliostat reflecting surface. 
     
     
         15 . The method of  claim 1 , wherein the data representing shape error includes a characterization of the shape of a heliostat reflecting surface. 
     
     
         16 . A heliostat control method implementable by a processor-based programmable controller connected to heliostats in a central tower solar thermal power generation system, solar thermal power generation system having a central receiver, the method controlling the heliostat aiming in real time and comprising:
 storing data representing shape error of each of a plurality of heliostats;   selecting aiming points on the surface of the central receiver for each of said plurality of heliostats and generating control signals to aim said each of said plurality of heliostats responsively to a focus error respective to each of said plurality of heliostats, where the focus error is such that a flux distribution on said central receiver generated by said each of said plurality of heliostats varies with apparent angle of the sun and with possible aiming points from which said aiming points is selected, the selecting being performed at a plurality of times responsive to at least apparent angle of the sun such that a selected aiming point for each of said plurality of heliostats is changed during a single day.   
     
     
         17 . The method of  claim 16 , wherein the selecting is responsive to a predefined constraint on the total flux received at said central receiver surface. 
     
     
         18 . The method of  claim 17 , wherein the constraint varies over time. 
     
     
         19 . The method of  claim 17 , wherein the constraint is determined to compensate for aging of the receiver. 
     
     
         20 . The method of  claim 17 , wherein the constraint is determined to compensate for changes in the reflectivity of the receiver. 
     
     
         21 . The method of  claim 17 , wherein the constraint is responsive to the temperature of the receiver. 
     
     
         22 . The method of  claim 17 , wherein the constraint is responsive to conditions that affect the temperature of the receiver. 
     
     
         23 . The method of  claim 22 , wherein the conditions that affect the temperature of the receiver include wind speed, relatively humidity, flow in the central receiver, flow per loop in the central receiver. 
     
     
         24 . The method of  claim 22 , further comprising generating data representing shape error of each of a plurality of heliostats responsively to measurements of said each of a plurality of heliostats. 
     
     
         25 . The method of  claim 22 , wherein the plurality of heliostats is a subset of all the heliostats in said central tower solar thermal power system. 
     
     
         26 . The method of  claim 22 , wherein the selecting is performed at a plurality of times responsive to a time of year. 
     
     
         27 . The method of  claim 22 , wherein the selecting is performed at a plurality of times responsive to a weather condition. 
     
     
         28 . The method of  claim 22 , wherein the selecting is performed at a plurality of times responsive to a performance condition of said each of said plurality of heliostats. 
     
     
         29 . The method of  claim 16 , wherein the data representing shape error includes a characteristic of the shape of a heliostat reflecting surface. 
     
     
         30 . The method of  claim 16 , wherein the data representing shape error includes a characterization of the shape of a heliostat reflecting surface. 
     
     
         31 . A heliostat control method implementable by a processor-based programmable controller connected to heliostats in a central tower solar thermal power generation system, solar thermal power generation system having a central receiver, the method controlling the heliostat aiming in real time and comprising:
 storing data representing shape error of each of a plurality of heliostats;   calculating, respective to each of a plurality of sun positions relative to the solar thermal power generation system, respective aiming points for each of said plurality of heliostats, the aiming points being target locations on the surface of said central receiver;   said calculating being responsive to a shape and position of a receiver of said central receiver relative to said each of a plurality of heliostats, said each of a plurality of sun positions, and said data representing shape error of said each of a plurality of heliostats;   generating control command signals to aim said plurality of heliostats responsively to said calculating.   
     
     
         32 - 75 . (canceled)