Steam turbine overspeed protection method and system

Abstract

A method and system is disclosed for generating a steam turbine overspeed control system fault alert. The method can include providing an overspeed control system with a control valve configured and located to adjust a speed of the steam turbine, the control valve having a control position. The method can also include monitoring the control position of the control valve and detecting a deloading event. Upon detection of a deloading event, a control system fault alert is generated when the control valve does not achieve a predefined control position within a predefined time from the deloading event.

1 . A method for generating a steam turbine overspeed control system fault alert comprising:
 providing an overspeed control system with a control valve configured and located to adjust a speed of the steam turbine, the control valve having a control position;   monitoring the control position of the control valve;   detecting a deloading event; and   generating a control system fault alert when the control valve does not achieve a predefined control position within a predefined time from the deloading event.   
     
     
         2 . The method of  claim 1  wherein the deloading event is a predefined steam turbine speed. 
     
     
         3 . The method of  claim 2  wherein the predefined time is substantially zero. 
     
     
         4 . The method of  claim 2  wherein the steam turbine is a component of a power plant with a generator, wherein the detecting a deloading event includes detecting the opening of a power breaker of the power plant. 
     
     
         5 . An overspeed control system for generating a steam turbine overspeed fault alert, comprising:
 a control valve configured and located to adjust a speed of the steam turbine, the control valve having a control position;   a monitor for monitoring the control position of the control valve;   a detector for detecting a deloading event; and   a controller for generating a control system fault alert when the control valve does not achieve a predefined control position within a predefined time from the deloading event.   
     
     
         6 . The overspeed control system of  claim 4 , wherein the deloading event is a predefined steam turbine speed. 
     
     
         7 . The overspeed control system of  claim 4 , wherein the predefined time is zero. 
     
     
         8 . A power plant comprising:
 a steam turbine having a generator and a power breaker; and   an overspeed control system including:
 a control valve configured and located to adjust a speed of the steam turbine, the control valve having a control position; 
 a monitor for monitoring the control position of the control valve; 
 a detector for detecting a deloading event; and 
 a controller for generating a control system fault alert when the control valve does not achieve a predefined control position within a predefined time from the deloading event. 
   
     
     
         9 . The power plant of  claim 8 , wherein the deloading event is a predefined steam turbine speed. 
     
     
         10 . The power plant of  claim 8 , wherein the detecting a deloading event includes detecting the opening of the power breaker of the power plant 
     
     
         11 . The power plant of  claim 8 , wherein the predefined time is substantially zero.