Solar light collecting method in multi-tower beam-down light collecting system

Abstract

It enhances heat collecting efficiency of sunlight received by heliostats. It is a solar light collecting method in a multi-tower beam-down light collecting system, including a tower selection. The multi-tower beam-down light collecting system is a system in which, in a field where a plurality of beam-down light collecting towers are present, light primarily reflected by heliostats 1 around each tower 4 is secondarily reflected by a reflector 3 at a top part of the tower 4 and is collected on a receiver 3 on the ground, and the tower selection is a process in which, assuming that the heliostat 1 in a given position receives sunlight and reflects the sunlight toward each of optionally selected two of the towers 4, 4 , a light receiving quantity on the receiver 3 of each of the towers 4 is compared, and one of the towers 4 in which the light receiving quantity is relatively large is selected to reflect the sunlight toward the one of the towers 4.

1 . A solar light collecting method in a multi-tower beam-down light collecting system, comprising a tower selection,
 wherein the multi-tower beam-down light collecting system is a system in which, in a field where a plurality of beam-down light collecting towers are present, light primarily reflected by a heliostat is secondarily reflected by a reflector at a top part of one of the towers and is collected on a receiver on the ground, and   wherein the tower selection comprises comparing, assuming that the heliostat in a given position receives sunlight and reflects the sunlight toward each of optionally selected two of the towers, a light receiving quantity on the receiver of each of the towers, and selecting one of the towers in which the light receiving quantity is relatively large to reflect the sunlight toward said one of the towers.   
     
     
         2 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 1 ,
 wherein, in the tower selection comprises comparing, assuming that the heliostat in the given position receives the sunlight and reflects the sunlight toward each of the optionally selected two of the towers, an angle formed by an directional vector of incident light and a directional vector of reflection light seen from the heliostat, evaluating the magnitude of the angle formed by the directional vector of the incident light and the directional vector of the reflection light seen from the heliostat, determining that a tower with respect to which the angle formed by the directional vector of the incident light and the directional vector of the reflection light seen from the heliostat is smaller is the tower in which the light receiving quantity is relatively large, and selecting said tower.   
     
     
         3 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 1 ,
 wherein the tower selection is performed based on results of a receiver light-receiving-quantity calculation, a whole-sky division, and a receiver light-receiving-quantity comparison,   wherein the receiver light-receiving-quantity calculation comprises calculating a light receiving quantity in each receiver assuming that a given heliostat reflects the sunlight toward each tower when the sun is in a given position,   wherein the whole-sky division comprises finding, based on the result of the receiver light-receiving-quantity calculation, a boundary line on the whole sky along which the light receiving quantity in each receiver becomes the same assuming that the given heliostat reflects the sunlight toward each tower, and dividing the whole sky by the boundary line,   wherein the receiver light-receiving-quantity comparison comprises, with respect to each area of the whole sky divided by the whole-sky division, comparing the light receiving quantity to be received by the receiver of each tower assuming that the heliostat reflects the light toward each tower, and evaluating the magnitude of the light receiving quantity to be received by the tower, and   wherein the tower selection comprises determining, based on the result of the receiver light-receiving-quantity comparison, which tower is to be selected when the sun is in the given position, controlling an orientation of the heliostat so that the heliostat reflects the sunlight toward the tower that is determined to be large in light receiving quantity, and reflecting the sunlight received by the heliostat toward the selected tower.   
     
     
         4 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 3 ,
 wherein the receiver light-receiving-quantity calculation comprises calculating the light receiving quantity to be received by the receiver of each towers assuming that the heliostat reflects the sunlight toward each tower when the sun is in a position of a given solar orientation and a given solar elevation.   
     
     
         5 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 3 ,
 wherein the receiver light-receiving-quantity calculation comprises calculating the light receiving quantity to be received by the receiver of each towers assuming that the heliostat reflects the sunlight toward each tower when the sun is in a position of a given solar orientation and a given solar elevation; and   wherein the whole-sky division comprises finding a solar elevation at which the light receiving quantity to be received by the receiver of each towers adjacent to each other becomes the same in the given solar orientation to find the boundary line along which the light receiving quantity to be received by the receiver of each towers adjacent to each other becomes the same, and dividing the whole sky by the boundary line.   
     
     
         6 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 1 ,
 wherein the tower selection is performed based on results of a receiver light-receiving-quantity calculation and a receiver light-receiving-quantity comparison;   wherein the receiver light-receiving-quantity calculation comprises calculating the light receiving quantity to be received by the receiver of each tower assuming that a given heliostat reflects the sunlight toward each tower when the sun is in a given position;   the receiver light-receiving-quantity comparison comprises comparing, based on the result of the receiver light-receiving-quantity calculation, the light receiving quantity to be received by the receiver of each tower assuming that reflection is made toward each tower; and   the tower selection comprises determining, based on the result of the receiver light-receiving-quantity comparison, which tower is to be selected, controlling an orientation of the heliostat so that the heliostat reflects the sunlight toward the tower that is determined to be large in the light receiving quantity to be received by the receiver, and reflecting the sunlight received by the heliostat toward the selected tower.   
     
     
         7 . The solar light collecting method in the multi-tower beam-down light collecting system as set forth in  claim 1 , wherein two or more towers are arranged at intervals among a group of heliostats dispersedly arranged on the ground, and each of the heliostats selects, in accordance with the tower selection, a specified tower such that the light receiving quantity to be received by the receiver becomes the largest.