Method and system for operating a solar steam system

Abstract

Methods, apparatus and systems for operating a solar steam system in response to a detected or predicted reduced or impending reduced insolation event are disclosed herein. Examples of transient reduced insolation events include but are not limited to cloud-induced reduction in insolation, dust-induced reduction in insolation, and insolation events caused by solar eclipses. In some embodiments, in response to the detecting or predicting, steam flow is regulated within the solar steam system to reduce a flow rate into a steam turbine. Alternatively or additionally, one or more heliostats may be responsively redirected onto a steam superheater or steam re-heater.

1 . A method of controlling a solar steam system, the solar steam system having a steam turbine and one or more solar receivers, the one or more solar receivers being selected from the group consisting of a solar steam superheater and a solar steam reheater, the method comprising:
 (a) generating steam from water using insolation incident on an evaporating solar receiver;   (b) using insolation incident on the solar steam superheater and/or the solar steam reheater to further heat steam provided thereto;   (c) detecting or predicting a current or impending transient reduced-insolation event; and   (d) in response to the detecting or predicting, regulating the flow of steam through the solar superheater and/or solar reheater such that the flow of steam from the solar superheater or the solar reheater into the steam turbine is reduced,   wherein the detecting or predicting includes at least one of:
 (i) analyzing digital images of a scene including one or more clouds; 
 (ii) measuring a level of dust present in the air using a laser; and 
 (iii) measuring a level of solar flux incident upon one or more of the solar receivers. 
   
     
     
         2 . The method of  claim 1 , wherein the current or impending transient reduced-insolation event is one of a cloud-induced reduced insolation event and a dust-induced reduction insolation event. 
     
     
         3 . The method of  claim 1 , wherein the detecting or predicting includes at least one of:
 (i) analyzing digital images of a scene including one or more clouds; and   (ii) measuring a level of dust present in the air using a laser.   
     
     
         4 . The method of  claim 1 , further comprising:
 (e) in response to an additional insolation level detection or prediction that occurs at a later time after the input flow rate of steam has been reduced, regulating the flow of steam through the solar superheater and/or solar reheater so that the flow rate into the steam turbine increases to previous level that prevailed before said regulating in (d).   
     
     
         5 . The method of  claim 4 , wherein the amount of flow reduction into the steam turbine is equal to at least 15% of the maximum flow rate of steam allowed into the steam turbine, and (d) and (e) are completed within a period of time that is less than 20 minutes. 
     
     
         6 . The method of  claim 1 , wherein the regulating of the flow of steam is carried out so as to reduce an input flow rate of steam into the steam turbine by an amount that is at least 15% of the maximum flow rate of steam allowed into the steam turbine within a time period that is less than 15 minutes. 
     
     
         7 . The method of  claim 6 , wherein the time period is less than 10 minutes. 
     
     
         8 . A method of controlling a solar steam system, the solar steam system having a steam turbine and one or more solar receivers, the one or more solar receivers being selected from the group consisting of a solar steam superheater and a solar steam reheater, the method comprising:
 (a) generating steam from water using insolation incident on an evaporating solar receiver;   (b) using insolation incident on the solar steam superheater and/or the solar steam reheater to further heat steam provided thereto;   (c) detecting or predicting a current or impending transient reduced-insolation event; and   (d) in response to the detecting or predicting, regulating the flow of steam through the solar superheater and/or solar reheater such that the flow of steam from the solar superheater or the solar reheater into the steam turbine is reduced,   wherein the reduction of the input flow rate of steam is carried out so that the pressure within the turbine remains substantially constant as the input flow rate of steam flow is reduced.   
     
     
         9 . The method of  claim 6 , further comprising:
 (e) in response to an additional insolation level detection or prediction that occurs at a later time after the input flow rate of steam has been reduced in (d), regulating the flow of steam through the solar superheater and/or solar reheater so that the flow rate into the turbine increases to a previous level that prevailed before the regulating in (d) and such that the pressure within the turbine remains substantially constant as the flow rate of steam into the turbine is increased.   
     
     
         10 . The method of  claim 1 , wherein a maximum power output of the turbine is at least 10 megawatts. 
     
     
         11 . The method of  claim 1 , wherein the flow reduction is carried out by means of a turbine inlet controller. 
     
     
         12 . The method of  claim 1 , wherein the system further comprises a steam separation vessel which feeds steam to the turbine via the solar steam receiver, and wherein the flow regulation is out by means of a valve located at an outlet of the steam separation vessel. 
     
     
         13 . The method of  claim 1 , wherein said detecting or predicting is of an impending reduced-insolation event.